Overheating solutions
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    Opeler Mr DJ-GT's Avatar
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    Overheating solutions

    I’m just an old school, multi generation Opel fan, & former street mechanic... I’m not a professional one like many of the experts here, however I do know a few time tested engine cooling remedies I’d like to share... If you have any overheating or gas boiling issues the absolute best anti freeze I’ve found unfortunately is the most expensive at about 20 bucks a gallon, but should always be bought full strength so you don’t pay five bucks or more for a half gallon of water when you can use your own... It’s a golden colored elixir engineered especially for hot running engines like Opel blocks & others... It’s called Prestone Dex Cool Extended Life for GM vehicles... That, & you should check your thermostat to make sure it’s not rusted from running too much water in the cooling system because running straight water will usually run hotter & tends to corrode a lot of interior components... Consider the option of a lower temperature thermostat, or in extreme cases of very hot environments (none at all) as a temporary solution to see if that’s your issue... It’ll cause much longer warm-ups & you don’t get that nice regulated temperature throughout the engine, but if you live in a very hot desert, it probably wouldn’t matter as much, as I’ve experienced several desert dwellers doing jus that... The factory heat sheild normally installed at the base of your stock Opel carburetor is a must to prevent gas boiling, along with sleeving any metallic gas line sections near the engine in slightly oversized rubber fuel line hose to insulate it... An (Oil Dam), which is a little round metallic sleeve that snugly fits inside the rear oil return port on your cylinder head keeps the cooling oil level in the head higher & longer is also another inexpensive helper to cool your GT head & increase head lubrication. Although they say the heater hose hook up positions doesn’t really matter, but I prefer my feed line on top & my return on the bottom so the return is gravity fed back more rapidly into the core for a smoother flow, & prevents that gurgling sound due to air in the system that many Opels get, especially when you open the heater valve... A ribbed plastic covered (cool flow) aluminum, pre-carburetor mounted fuel filter is another cheap way to help prevent gas boiling as it cools the gas down and a small reservoir right before it enters the carb, & a little safer in a hot environment than straight plastic filters... A double core, triple core, or new plastic radiators, electric radiator mounted fan setups, or my preferred 7 bladed clutch fans with it’s own water pump setup are a little more expensive sometimes, but are very effective for superior cooling, tho electric fans drain a lot of battery power if you’re running low amp electrical systems... The clutch fan system works with centrifical force & relieves engine stresses at low to high rpms that’s normally caused by resistance of the stock 5 & 6 bladed fans... If you can get an old style Volkswagen oil cooler & flush it out before mounting it to the opposite outer side of the charcoal canister reinforcement bar in the front grill area, & connect it into your cooling system with T, or Y connectors controlled by a heater hose shut off valve on the feed line, will also make a dramatic difference... Combinations of these should make a world of difference in cooling down your Opel engine... <>Dj<>
    Last edited by Mr DJ-GT; 3 Weeks Ago at 06:20 AM. Reason: Add my signature stamp
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    Senior Member The Cub's Avatar
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    Some good suggestions as cooling down the GT is usually a challenge due to the compact engine bay. Iíd be interested in learning more about this clutch fan. This is the second or third time Iíve read about it but no details on the installation or who makes a good one for our application. Iíve recently purchased an electric fan, my ultimate goal is to abandon the stock fan as mentioned above, itís needless noise and a slight HP robber in the mid to upper RPM range. Also stop & go for extended periods is and will always be a problem with the stock cooling fan in my experience. Iím also doing other things more specific to the manifold such as getting rid of the stock chimney set up for one. In the warm climate Iím in itís a not a good set up much better for colder climates, and Iím sure Iíll miss some of its benefits. I like your suggestion to insulate the fuel line in the engine compartment, another on my to do list.
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    I don't know if this would help you but I am in central texas with a hot climate too. I am running a new stock style fan and the aluminum radiator from OGTS. I also have A/C and I am not experiencing any overheating problems whatsoever.
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    Quote Originally Posted by Mr DJ-GT View Post
    I’m just an old school, multi generation Opel fan, & former street mechanic... I’m not a professional one like many of the experts here, however I do know a few time tested engine cooling remedies I’d like to share... If you have any overheating or gas boiling issues the absolute best anti freeze I’ve found unfortunately is the most expensive at about 20 bucks a gallon, but should always be bought full strength so you don’t pay five bucks or more for a half gallon of water when you can use your own... It’s a golden colored elixir engineered especially for hot running engines like Opel blocks & others... It’s called Prestone Dex Cool Extended Life for GM vehicles... That, & you should check your thermostat to make sure it’s not rusted from running too much water in the cooling system because running straight water will usually run hotter & tends to corrode a lot of interior components... Consider the option of a lower temperature thermostat, or in extreme cases of very hot environments (none at all) as a temporary solution to see if that’s your issue... It’ll cause much longer warm-ups & you don’t get that nice regulated temperature throughout the engine, but if you live in a very hot desert, it probably wouldn’t matter as much, as I’ve experienced several desert dwellers doing jus that... The factory heat sheild normally installed at the base of your stock Opel carburetor is a must to prevent gas boiling, along with sleeving any metallic gas line sections near the engine in slightly oversized rubber fuel line hose to insulate it... An (Oil Dam), which is a little round metallic sleeve that snugly fits inside the rear oil return port on your cylinder head keeps the cooling oil level in the head higher & longer is also another inexpensive helper to cool your GT head & increase head lubrication. Although they say the heater hose hook up positions doesn’t really matter, but I prefer my feed line on top & my return on the bottom so the return is gravity fed back more rapidly into the core for a smoother flow, & prevents that gurgling sound due to air in the system that many Opels get, especially when you open the heater valve... A ribbed plastic covered (cool flow) aluminum, pre-carburetor mounted fuel filter is another cheap way to help prevent gas boiling as it cools the gas down and a small reservoir right before it enters the carb, & a little safer in a hot environment than straight plastic filters... A double core, triple core, or new plastic radiators, electric radiator mounted fan setups, or my preferred 7 bladed clutch fans with it’s own water pump setup are a little more expensive sometimes, but are very effective for superior cooling, tho electric fans drain a lot of battery power if you’re running low amp electrical systems... The clutch fan system works with centrifical force & relieves engine stresses at low to high rpms that’s normally caused by resistance of the stock 5 & 6 bladed fans... If you can get an old style Volkswagen oil cooler & flush it out before mounting it to the opposite outer side of the charcoal canister reinforcement bar in the front grill area, & connect it into your cooling system with T, or Y connectors controlled by a heater hose shut off valve on the feed line, will also make a dramatic difference... Combinations of these should make a world of difference in cooling down your Opel engine...
    I believe the fan clutch you're speaking of came on the 75 Opels. They work ok, but unless you can source a new one, it, like the cars are over 40 years old. Another one would be Water wetter, helped mine a lot. The electric fan setup I have, but it's thermostat controlled with a probe inserted into a 3 core radiator. When the radiator was re cored, I added a drain plug to it. I mounted a 2 core finned oil cooler into the front frame rail as a gas cooler and it seems to work well. Good tips though. Jarrell
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    Quote Originally Posted by Mr DJ-GT View Post
    I’m just an old school, multi generation Opel fan, & former street mechanic... I’m not a professional one like many of the experts here, however I do know a few time tested engine cooling remedies I’d like to share... If you have any overheating or gas boiling issues the absolute best anti freeze I’ve found unfortunately is the most expensive at about 20 bucks a gallon, but should always be bought full strength so you don’t pay five bucks or more for a half gallon of water when you can use your own... It’s a golden colored elixir engineered especially for hot running engines like Opel blocks & others... It’s called Prestone Dex Cool Extended Life for GM vehicles... That, & you should check your thermostat to make sure it’s not rusted from running too much water in the cooling system because running straight water will usually run hotter & tends to corrode a lot of interior components... Consider the option of a lower temperature thermostat, or in extreme cases of very hot environments (none at all) as a temporary solution to see if that’s your issue... It’ll cause much longer warm-ups & you don’t get that nice regulated temperature throughout the engine, but if you live in a very hot desert, it probably wouldn’t matter as much, as I’ve experienced several desert dwellers doing jus that... The factory heat sheild normally installed at the base of your stock Opel carburetor is a must to prevent gas boiling, along with sleeving any metallic gas line sections near the engine in slightly oversized rubber fuel line hose to insulate it... An (Oil Dam), which is a little round metallic sleeve that snugly fits inside the rear oil return port on your cylinder head keeps the cooling oil level in the head higher & longer is also another inexpensive helper to cool your GT head & increase head lubrication. Although they say the heater hose hook up positions doesn’t really matter, but I prefer my feed line on top & my return on the bottom so the return is gravity fed back more rapidly into the core for a smoother flow, & prevents that gurgling sound due to air in the system that many Opels get, especially when you open the heater valve... A ribbed plastic covered (cool flow) aluminum, pre-carburetor mounted fuel filter is another cheap way to help prevent gas boiling as it cools the gas down and a small reservoir right before it enters the carb, & a little safer in a hot environment than straight plastic filters... A double core, triple core, or new plastic radiators, electric radiator mounted fan setups, or my preferred 7 bladed clutch fans with it’s own water pump setup are a little more expensive sometimes, but are very effective for superior cooling, tho electric fans drain a lot of battery power if you’re running low amp electrical systems... The clutch fan system works with centrifical force & relieves engine stresses at low to high rpms that’s normally caused by resistance of the stock 5 & 6 bladed fans... If you can get an old style Volkswagen oil cooler & flush it out before mounting it to the opposite outer side of the charcoal canister reinforcement bar in the front grill area, & connect it into your cooling system with T, or Y connectors controlled by a heater hose shut off valve on the feed line, will also make a dramatic difference... Combinations of these should make a world of difference in cooling down your Opel engine... <>Dj<>
    I’m glad to see my old school suggestions can actually help other Opel Family members... First of all, I was reminded by my uncle Joe that the ultra light weight GT’s unladen weight was actually listed at 1,250 pounds, not 1,300 pounds as I previously stated in another post... “My bad”, I was thinking of my air-conditioned 73 model Gt...

    Thanks for the vote of confidence to a non-professional who’s only been working on GT’s, to Cadets over 30 years in the southern California climate, that preserves vintage cars like you wouldn’t believe... I’m afraid I’ve posted in several different sections here, so if it’s possible to look up everything I wrote in one place you may also see a lot more little time tested technical innovations on both mechanical & electrical improvements,” along with a few confusing typos I’d like to go back & correct if at all possible :{
    Last edited by Mr DJ-GT; 3 Weeks Ago at 07:25 PM. Reason: Typo
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    Quote Originally Posted by The Cub View Post
    Some good suggestions as cooling down the GT is usually a challenge due to the compact engine bay. Iíd be interested in learning more about this clutch fan. This is the second or third time Iíve read about it but no details on the installation or who makes a good one for our application. Iíve recently purchased an electric fan, my ultimate goal is to abandon the stock fan as mentioned above, itís needless noise and a slight HP robber in the mid to upper RPM range. Also stop & go for extended periods is and will always be a problem with the stock cooling fan in my experience. Iím also doing other things more specific to the manifold such as getting rid of the stock chimney set up for one. In the warm climate Iím in itís a not a good set up much better for colder climates, and Iím sure Iíll miss some of its benefits. I like your suggestion to insulate the fuel line in the engine compartment, another on my to do list.
    My two main sources for Opel parts are as follows: If you need clutch fan set ups speak to Gil or his associates at (Opel GT source com), heís an amazing managerial/technician who approached me maybe 25/30 years ago & I used to comeout & get parts rite from his backyard in the SF valley... I haggled over every little dollar & he had a lot of patience with me... Now heís so international I can hardly speak with him unless Iím ordering major parts, but heís absolutely the best in the United States for technical data, & upgraded, remanufactured Opel parts, like clutch fan set ups, multicore radiators, high-performance headers, custom exhausts & brakes set ups, you name it, etc, etc... Heís truly brilliant, but a little pompous sometimes like many geniuses...

    My other source other is TODD, heís an absolute monolith for Original opel parts, at (Opels Unlimited.com) in Riverside, Ca... Heís also is a certified appraiser who bailed me out (along with Gil) when my GT got sandwiched between two larger cars & their insurance company tried to lowball me... Todd will even go to court on your behalf if needed as a qualified expert... He also has a vast selection of remanufactured parts, like the clear or transparent color matching distributor caps that lets you see the spark intensities & which ones are missing & much more... You could actually drive to Riverside from Southern California & cherry pick any parts you want from dozens of stock Opel models to complete stock, customized, convertible, & even cabaret top GTís for sale, rite from his warehouses... Todd even has a rare first generation split bumper 68 GT, & probably an Opel Capípiítan, which is that very rare Opel limousine... Between Gil & Todd youíre find anything you need for just about any Opel model... If these two giants ever joined forces they would dominate the entire U.S., & probably half the international market too...
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    Opeler Mr DJ-GT's Avatar
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    Quote Originally Posted by pumpkindriver View Post
    I don't know if this would help you but I am in central texas with a hot climate too. I am running a new stock style fan and the aluminum radiator from OGTS. I also have A/C and I am not experiencing any overheating problems whatsoever.
    Iíve learned a lot from you guys, so itís only fair that I share what little I know, and that idea of an aluminum GT radiator is something Iíve never heard of and worth looking into... Especially if they make a (double core) aluminum radiator... Kindly provide your source... Coolant capacity is a big improvement because original radiators were probably designed for the 68/69 GTís 1.1 L engine which looked much like a little sewing machines, and sounded like one too :}

    But of course, back then, the kneejerk reaction was to just drop a Chevy 283 V-8 in one to create a pocket rocket, but with all that weight in the front, it threw GTs off balance, even with the lifted front suspensions... They wrapped a lot of them around trees & telephone polls because that was way too much power for the lack of stability control innovations of the day... however, it,,, along with the old Chevy 327 turbo jet engines was absolutely great for drag strip GTs...
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    It is VERY hot and humid where I live. I think yesterday we were the hottest in the Northeast.

    I use both the 7 blade engine fan and a 14" electric fan on a thermostat set for 180*. I use the 3-core copper heavy duty radiator, which is supposed to be about as good as their aluminum one. I think the aluminum ones are 3-core. I'll probably get one simply because they look so good. Nothing I tried over 40 years stopped the carb from boiling in stopped traffic or after a brief shut down on a hot day. I tried every single thing that guys will say fixed their problem, none worked. My GT's always have automatics, which makes the car run hotter and poorly when idling. The boiling only stopped when I bought the offset Steinmetz single side draft manifold, which moves the carburetor away from the exhaust pipes.

    Keeping your engine slightly rev'd(and in neutral with an auto) when stopped in traffic helps alot. In an emergency overheating situation you can turn on your heater and the fan at full blast and gain about 10-15% more cooling. Yes, you'll roast like a turkey, but your engine will live to tell the tale. A good quality 14" electric fan will usually make ANY radiator cool your car enough.
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    Quote Originally Posted by soybean View Post
    I believe the fan clutch you're speaking of came on the 75 Opels. They work ok, but unless you can source a new one, it, like the cars are over 40 years old. Another one would be Water wetter, helped mine a lot. The electric fan setup I have, but it's thermostat controlled with a probe inserted into a 3 core radiator. When the radiator was re cored, I added a drain plug to it. I mounted a 2 core finned oil cooler into the front frame rail as a gas cooler and it seems to work well. Good tips though. Jarrell
    Thatís very interesting to add a gas cooler, but it doesnít get quite that hot here in Southern Cali unless you live in one of our deserts, so generally the factory heat shield at the base of the carb along with an insulated gas line & a ribbed (cool flow) pre carb mounted refillable filter I found at pep boys usually does the trick for gas boiling in the carb... For the engineI took an old VW oil cooler & mounted it in the front grill area on the opposite side of my charcoal canister, & piped it into my regular cooling system using a regular heater hose shut off valve that I wired to a manual choke cable mounted under my glove compartment... I can open it when I need extra (air cooled) coolant capacity, & close it when itís cold or rainy to get normal heat inside from my core... I even saw one hooked up on a GT as an oil cooler to give it an extra cool oil capacity... I also got my rear view & rear sideview aircraft quality aluminum window louvers from (Opel GT source) & they keep my inside cab really cool along with tinted drivers & passenger windows with a deep dark green stock front windshield I got from (Opels Unlimited) where you can cherry pick your own parts... I never even need to use my AC with those twin pop open windows... On most of my posts here I generally list my sources so I wonít leave anybody hanging, but a lot of my stuff was found at wrecking yards where itís a crapshoot every time you go because you never know what buried treasures you might find...
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    Opeler Mr DJ-GT's Avatar
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    Quote Originally Posted by The Scifi Guy View Post
    It is VERY hot and humid where I live. I think yesterday we were the hottest in the Northeast.

    I use both the 7 blade engine fan and a 14" electric fan on a thermostat set for 180*. I use the 3-core copper heavy duty radiator, which is supposed to be about as good as their aluminum one. I think the aluminum ones are 3-core. I'll probably get one simply because they look so good. Nothing I tried over 40 years stopped the carb from boiling in stopped traffic or after a brief shut down on a hot day. I tried every single thing that guys will say fixed their problem, none worked. My GT's always have automatics, which makes the car run hotter and poorly when idling. The boiling only stopped when I bought the offset Steinmetz single side draft manifold, which moves the carburetor away from the exhaust pipes.

    Keeping your engine slightly rev'd(and in neutral with an auto) when stopped in traffic helps alot. In an emergency overheating situation you can turn on your heater and the fan at full blast and gain about 10-15% more cooling. Yes, you'll roast like a turkey, but your engine will live to tell the tale. A good quality 14" electric fan will usually make ANY radiator cool your car enough.
    Wow Si-Fi guy, sounds like a desert where you live.... but you use some of the same tricks I used to when I over heated, such as revving the engine at a steady, higher RPM & opening my heater valve wide open. Of course I had all the windows open at the time... The automatic transmission does add a lot of engine stress, but probably weights no more than the eight speed manual Getrag transmissions both Gil & Todd sells for Opels... Glad I never have anymore overheating issues, but was actually having trouble getting interior heat when I needed it with the expanded cooling set up I installed, before I thought to add the heater coolant shut off valve...
    Last edited by Mr DJ-GT; 3 Weeks Ago at 07:20 PM. Reason: double word
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    Just Some Dude in Jersey The Scifi Guy's Avatar
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    It's the humidity that's the problem. I've been out in Oklahoma for weeks on end when it was 108* every day and it wasn't nearly as bad as around here when it's 95* with 50+% humidity. My part of the State has ocean water on 3 sides and most of the southern part of Jersey used be or still is a swamp.
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    Here is a serious warning about Dexcool in general in older cooling systems. There have been many, many cases of Dexcool sludging very, very badly in engines not designed for them, so badly as to cause serious clogging and serious overheating problems.

    The issue, it turns out, is that at elevated temps, any air entrained in the coolant will react with the Dexcool base and cause this sludging problem. What you don't know in an older engine is if it typically has entrained air in the coolant. (And this can also happen to a cooling designed for Dexcool that is leaky and not properly re-filled, or run low on coolant and gets air in the system in that manner.)

    Cavitation around the water pump blade tips is one very common source of this problem. Because of this cavitation issue, Ford (and I think another mfr) ended a certain engine production life early, to re-design in a new engine with a cooling system, including the pump, to avoid cavitation and air in the coolant so that Ford COULD switch to Dexcool type coolants, for the long life. I have no reason to think that these Opel water pump designs had any regard for being cavitation-free.

    Another problem area is any cooling system that has an air gap in the top of the cooling system... like these Opel system do! To use Dexcool and keep all the air out of the system, you need to have a system where the filler is at the absolute highest point in the cooling system, and has a method to 100% bleed all air out of the cooling system, including having a coolant recovery system. The vintage Opels do not have this, unless they have an elevated fill tank (like the old Saab 99's of this same era). I know the Manta's and 1900's do not have this feature. If you hear coolant gurgling around as the engine cools off after stopping, then you can be 100% sure there is air in the system all the time, and these 50 series Opels always have done this. I don't know the GT's design to be able to say.

    Head cooling design and system pressure also play into this, but you get the idea.....The engines cooling system has to be designed explicitly for Dexcool to avoid this problem.

    I do not want to gratuitously rain on anyone's 100% sincere recommendation, but these sludging issues have been going on with Dexcool for years and years; the cause is just not well known in the gear-head crowd. So no, I will not be putting Dexcool in my Opel(s) (Manta's & 1900's). I'm 99% it will indeed have air entrainment problems and eventual sludging.

    If you want a longer life coolant that does NOT have the sludging problems of Dexcool then consider Zerex G-05.
    Last edited by Manta Rallier; 3 Weeks Ago at 07:38 PM.
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    Quote Originally Posted by Manta Rallier View Post
    Here is a serious warning about Dexcool in general in older cooling systems. There have been many, many cases of Dexcool sludging very, very badly in engines not designed for them, so badly as to cause serious clogging and serious overheating problems.

    The issue, it turns out, is that at elevated temps, any air entrained in the coolant will react with the Dexcool base and cause this sludging problem. What you don't know in an older engine is if it typically has entrained air in the coolant. (And this can also happen to a cooling designed for Dexcool that is leaky and not properly re-filled, or run low on coolant and gets air in the system in that manner.)

    Cavitation around the water pump blade tips is one very common source of this problem. Because of this cavitation issue, Ford (and I think another mfr) ended a certain engine production life early, to re-design in a new engine with a cooling system, including the pump, to avoid cavitation and air in the coolant so that Ford COULD switch to Dexcool type coolants, for the long life. I have no reason to think that these Opel water pump designs had any regard for being cavitation-free.

    Another problem area is any cooling system that has an air gap in the top of the cooling system... like these Opel system do! To use Dexcool and keep all the air out of the system, you need to have a system where the filler is at the absolute highest point in the cooling system, and has a method to 100% bleed all air out of the cooling system, including having a coolant recovery system. The vintage Opels do not have this, unless they have an elevated fill tank (like the old Saab 99's of this same era). I know the Manta's and 1900's do not have this feature. If you hear coolant gurgling around as the engine cools off after stopping, then you can be 100% sure there is air in the system all the time, and these 50 series Opels always have done this. I don't know the GT's design to be able to say.

    Head cooling design and system pressure also play into this, but you get the idea.....The engines cooling system has to be designed explicitly for Dexcool to avoid this problem.

    I do not want to gratuitously rain on anyone's 100% sincere recommendation, but these sludging issues have been going on with Dexcool for years and years; the cause is just not well known in the gear-head crowd. So no, I will not be putting Dexcool in my Opel(s) (Manta's & 1900's). I'm 99% it will indeed have air entrainment problems and eventual sludging.

    If you want a longer life coolant that does NOT have the sludging problems of Dexcool then consider Zerex G-05.
    Thank you for that enlightened presentation, so I’ll stop recommending it for any systems without a sound coolant reservoir... I had no idea it reacted negatively with air under heat & pressure...

    Of course, my GT has twin coolant reservoir‘s, One is right next to the radiator where the snorkel used to be, & my radiator is always filled to the top whenever I check my overflow spout out of habit for any build ups... I also have a 2nd reservoir right where the battery compartment used to be to make it a two-step cooling system that catches any overflow & feeds it back into the top reservoir on heavy demands to further prevent any chance of air in the system... I never mix my antifreeze with the cheaper green stuff...

    That combined with a VW type oil cooler piped directly into the cooling system that feeds in on top & returns (gravity fed) on the bottom is specifically to avoid air in the system, & no gurgling sound like a lot of Opels get when they turn on their heater valve...

    With my set up I can run straight antifreeze with no water if desired, & it still never boils or overheats, nor have I ever had a problem with sludge since I’ve been using (Extended Life) Dex cool for well over a decade now that I can finally afford to... I’ve had plenty of sludge using that green stuff & used to overheat constantly to boot...

    So I guess I’m just one of the Lucky ones, because I installed my first coolant recovery reservoir about 20 years ago converted from an Opel windshield washer reservoir & my 2nd one about 10 or 15yrs ago is a slimmer, hexagon shaped one from (Auto Zone) that fits right in my engine compartment about 5 inches away from my radiator jus a bit higher, & feeds the radiator directly from it’s bottom... Additionally, it’s mounted right under the hood’s outward flowing forward cooling vents... My system is so airtight & clean you can practically drink out of it... :}> yuk “Metaphorically of course”

    I’ve also been warned not to use synthetic oil in my GT but with every change I put in 1 quart of Mobile 1, 15/50 weight along with my normal organic formulation of 20/50wt topped with a quart of Valvoline straight 50wt racing oil for over a decade now, for quicker warm ups & superior thermo protection... I’m still waiting for all the oil leaks they swore I would get... But thanks for the new Antifreeze recommendation my friend, because if anyone knows of a better mouse trap, I’m always game to give it a whirl... Provided I can afford it :}
    Last edited by Mr DJ-GT; 3 Weeks Ago at 09:41 PM.
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  16. #14
    2000 Post Club soybean's Avatar
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    Well, I believe I have a new one on ya'll. I actually have a bleeder valve on top of my thermostat housing that is used to get the air out. I can post pics in the Am. Another trick that Rallye Bob told me when I rebuilt my engine was to take the old head gasket lay it on the new one. Find the coolant holes that were never opened on nos 2 and nos 3 cyl, they will show up on the old gasket. Punch them out on the new gasket for improved coolant flow. Opel left those 2 from the block closed for some reason. Hth, Jarrell
    You lose your dreams, you lose your mind. (The Rolling Stones)
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    Opeler Mr DJ-GT's Avatar
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    Quote Originally Posted by soybean View Post
    Well, I believe I have a new one on ya'll. I actually have a bleeder valve on top of my thermostat housing that is used to get the air out. I can post pics in the Am. Another trick that Rallye Bob told me when I rebuilt my engine was to take the old head gasket lay it on the new one. Find the coolant holes that were never opened on nos 2 and nos 3 cyl, they will show up on the old gasket. Punch them out on the new gasket for improved coolant flow. Opel left those 2 from the block closed for some reason. Hth, Jarrell
    Thatís very interesting Soybean, Iíll do that when I order a new head gasket.. I would also like to see what your relief valve looks like because thatís another new one for me... That brings me to another point of someting that supposedly couldnít be, & that was to re-torque down the same new head gasket & road test it 2 or 3 times like I had to do when I got my current 2.0 SHO engine from a batch of low mileage used ones freshly imported from Germany, because itís original cylinder head was milled down so far the valves were tapping the pistons & I couldnít get a hold of one of those double or triple thick head gaskets... After putting a new timing chain and glides and rebuilding oil pump, I open it up at third time to finally replace the cylinder head as a last resort & it worked beautifully ever since... I needed to move it twice a week back then for street sweeping because I parked on the streets so I couldnít waste time hunting down a double or triple thick head gasket after re-measuring it in a shop...

    I just put some Aviation Gasket sealer around the timing chain section & sprayed the whole thing down with Permatex Copper spray... The compression held beautifully every time... Itís been several years now with the same great cylinder compressions & no leaks... Aviation gasket sealer is hard to find now, so I use Permatex High Tack instead for my super heavy non-hardening sealing needs like the base of my carbs & heat shield gaskets etc. I use their fine copper spray for my ultra lite to reg lightweight seals like from rebuilding a carb to replacing my valve cover gasket.
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  18. #16
    2000 Post Club soybean's Avatar
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    Relief valve

    Quote Originally Posted by Mr DJ-GT View Post
    That’s very interesting Soybean, I’ll do that when I order a new head gasket.. I would also like to see what your relief valve looks like because that’s another new one for me..
    Pic 1 is relief valve. Pic 2 is oil/gas cooler from grill. Pic 3 is from top showing lines into cooler. Pic 4 is my other ride. 2006 350Z, a few upgrades done. Will hit 60 in 2nd gear. Fastest I've had it was 140 in 5th and still had 1 more gear to shift into, but I had no guts to shift into 6th. Jarrell
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    Last edited by soybean; 3 Weeks Ago at 10:14 AM.
    You lose your dreams, you lose your mind. (The Rolling Stones)
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  19. #17
    Opel Rallier since 1977
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    If you can bleed all the air out of the system at the highest point, then you are in good shape for part of the Dexcool and air problems. I can't say if the water pumps are appropriate though so keep an eye on that. Please note that if you have the Dexcool sludging problem, it is in a class by itself compared to sludge seen with the green antifreezes. Just Google 'dexcool sludging' and look at the images!

    As for cooling properties, I am not aware that Dexcool transfers heat any better that anything else. It's claim to fame is long change intervals, and with car mfr's chasing the holy-grail of 'no-maintenace' car design, that is what is pushing them towards that type of coolant. But HOAT anti-freezes (like the Zerex G-05) are doing 5+ year intervals.

    Any better cooling that you may have seen with Dexcool is more likely a collateral effect of good practices of bleeding all the air out. If you can do that, you can run higher system pressures, which helps to limit localized boiling around the combustion chambers.

    As for the hole(s) not opened in the head gasket, I have seen that on many Mopar engines, small blocks and the /6's. The idea is that the coolant flows back through the block, up through the biggest holes in the back, and then forward through the head. Keeping those holes closed helps that flow pattern, and makes sure that the back cylinder(s) gets adequate coolant flow. But added flow in the middle may keep hot spots on certain combustion chambers under better control; that can reduce detonation tendencies a bit and also better control localized boiling by the chambers. And maybe the later heads will not crack so easily in #2 and #3 chambers. Interesting.....
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  20. #18
    2000 Post Club soybean's Avatar
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    Quote Originally Posted by Manta Rallier View Post
    And maybe the later heads will not crack so easily in #2 and #3 chambers. Interesting.....
    That was what Bob was telling me before I punched those 2 holes out and the reason why I punched them out. Out of 5 engines in my shed, 4 heads were cracked when they were magnafluxed. (sp). Jarrell
    You lose your dreams, you lose your mind. (The Rolling Stones)
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  21. #19
    Tennessean Site Supporter hrcollinsjr's Avatar
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    Quote Originally Posted by Manta Rallier View Post
    If you want a longer life coolant that does NOT have the sludging problems of Dexcool then consider Zerex G-05.
    Any thoughts on the coolants that claim they mix with any color and won't void manufacturers warranties? I've started using it more and more from my tractor with an aluminum radiator to some of my vehicles. My GT appears to have Dex Cool in it. Had to replace the water pump an few weeks ago. Hoping to slowly get rid of the Dex Cool, mainly because of compatibility issues with other coolants.

    Harold

    P.S. Noticed the other day that Chrysler has been using Dex Cool since, 2013?
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  22. #20
    GT Owner opelgt722002's Avatar
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    Quote Originally Posted by soybean View Post
    That was what Bob was telling me before I punched those 2 holes out and the reason why I punched them out. Out of 5 engines in my shed, 4 heads were cracked when they were magnafluxed. (sp). Jarrell
    However, Gil is adamant that the gasket be left alone.
    Bob
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