overheating problem

[blancojp]

Hello Guys!
I have a small problem with a customer car that is really getting to me. The car has everything in the cooling system new but temperature creeps up slowly until it overheats.

The stats are new engine with 180lbs/cyl, water pump, 4-core radiator, 160 degree thermostat, all new hoses, green line coolant and flex-a-lite fan. The car runs well and there is no drag of any type while on the road. The system was pressurized and checked for leaks.

Any ideas???????

PS: any one has a radiator shroud they want to get rid off??

[Stanley_P]

Just a couple things,
1. Is the water pump working?
2. Is the fan turning in the right direction?

[tekenaar]

Originally Posted by blancojp Hello Guys! I have a small problem with a customer car that is really getting to me. The car has everything in the cooling system new but temperature creeps up slowly until it overheats. The stats are new engine with 180lbs/cyl, water pump, 4-core radiator, 160 degree thermostat, all new hoses, green line coolant and flex-a-lite fan. The car runs well and there is no drag of any type while on the road. The system was pressurized and checked for leaks. Any ideas??????? PS: any one has a radiator shroud they want to get rid off??

Change/check the T-stat . . . even brand new ones have been known to be defective.

Lower your coolant ratio to 25% (3:1) mix rather than 50% (1:1) you're probably using now or just use pre-mixed coolant, already 1:1, in 1:1 ratio with water . . . result 3:1!

[Tru-Craft]

Originally Posted by blancojp Hello Guys! I have a small problem with a customer car that is really getting to me. The car has everything in the cooling system new but temperature creeps up slowly until it overheats. The stats are new engine with 180lbs/cyl, water pump, 4-core radiator, 160 degree thermostat, all new hoses, green line coolant and flex-a-lite fan. The car runs well and there is no drag of any type while on the road. The system was pressurized and checked for leaks. Any ideas??????? PS: any one has a radiator shroud they want to get rid off??

Sounds like everything is new and correct!?
Maybe some water pump passage is partially blocked with permatex or the thermostat is sticking?
I would pull the thermostat and run without it to see what happens.
It has been really hot here in FL as you know.
I run a radiator cap that syphons, with a hose to a Geo Metro over flow bottle, it works good, the bottle level does change a lot.
I have not had a fan shroud on my car for years, with no over heating, but it could help. I have a partial one on now, A/C compressor is in the way.
If the car is running lean it could cause it to run hotter?
Lyle

[blancojp]

So far I have gone through three thermostats, two water pumps and one radiator. Fan is in properly but was replaced twice anyway. Engine block and head were checked twice and found no problems or obstrusions.

We pre-mix our cooland and I have changed the formula 4 times with no results. Even running the engine with distilled water does the same thing, works fine and temperature creeps up very slowly and overheats.

[Scorchr69]

Have you verified that you have water flow through the system?

As mentioned above could be a sticking or bad t-stat, or, I have seen an air pocket at the t-stat housing not allowing water to flow to it to open it before the engine over heats.

Last if you are not 100 % sure that it is truly overheating, check the sending unit. It may be the wrong one.

Good luck

[tekenaar]

Originally Posted by blancojp So far I have gone through three thermostats, two water pumps and one radiator. Fan is in properly but was replaced twice anyway. Engine block and head were checked twice and found no problems or obstrusions. We pre-mix our cooland and I have changed the formula 4 times with no results. Even running the engine with distilled water does the same thing, works fine and temperature creeps up very slowly and overheats.

Bubbles in radiator? . . . only other thing is combustion pressure leak into coolant, head gasket leak . . .

uh, how about block and/or head mating surfaces flatness?

[tekenaar]

Originally Posted by Tru-Craft Sounds like everything is new and correct!? Maybe some water pump passage is partially blocked with permatex or the thermostat is sticking? I would pull the thermostat and run without it to see what happens. It has been really hot here in FL as you know. I run a radiator cap that syphons, with a hose to a Geo Metro over flow bottle, it works good, the bottle level does change a lot. I have not had a fan shroud on my car for years, with no over heating, but it could help. I have a partial one on now, A/C compressor is in the way. If the car is running lean it could cause it to run hotter? Lyle

Not to belabor this unduly, but you'd be amazed at the difference a radiator fan shroud makes . . . primarily due to better air flow direction through radiator.

Because of underhood space limitations, GT is worst for shedding radiated underhood heat! ANY little thing helps . . . fan shroud, carb heat shield, non-metal can fuel filter, shrouding metal fuel line with plastic split loom wiring harness material . . .

[GTJIM]

At 180psi/cylinder compression pressure it sounds to me like that is a pretty high compression motor. 10:1 the ignition has to be run retarded to stop 'pinging' ..... and retarded ignition is one real culprit that causes hot running. Other than that I would suspect hot gasses leaking in to the coolant past a head gasket or through small, unseen cracks in the head.

Do you have the two extra cooling holes cut in to the head gasket under the centre exhaust ports? That really aids cooling a LOT.

[Manta Rallier]

Originally Posted by GTJIM At 180psi/cylinder compression pressure it sounds to me like that is a pretty high compression motor. 10:1 the ignition has to be run retarded to stop 'pinging' ..... and retarded ignition is one real culprit that causes hot running. Other than that I would suspect hot gasses leaking in to the coolant past a head gasket or through small, unseen cracks in the head. Do you have the two extra cooling holes cut in to the head gasket under the centre exhaust ports? That really aids cooling a LOT.

If it is creeping up slowly, I too would suspect compression gases leaking into the water jacket, assuming all else has been checked. You can check for this with a radiator cap with an integrated pressure guage from a rad shop. Once at or near normal operataing temp, the guage is read and should be rock solid steady. Any regular pulsing on the guage indicates a compression gas leak into the water jacket.

If this is the case, then this may be the classis cracks in #2 and 3 combustion chambers around the exhaust valve seats. This may no show up in testing cold.

Is this a later head? And, have you put an aftermarket temp guage in temporarily as a check?

Also, we have found that it takes 2-3 heating/cooling cyclces to get all the air out of the system. The Opel cooling system does not have an air bleeder stock but does tend to purge itself pretty well.

One other thing: If the electrical system is not properly grounded, then the temp guage is going to tend to read high. The temp sensor increases resistance with temp, which reduces guage current and moves the indicator higher. If the system is not grounded right, then the sensor will not see proper voltage, which reduces the guage current, simulating a higher temp in the engine. We 'fixed' a hot Manta a few days back by simply re-attaching the ground at the battery negative terminal to the chassis; voila! normal engine temps.

Hope this helps.

Mark B.

[namba209]

JB, Two things I would suggest. First use a cooking thermometer in the radiator filler neck to be sure it is overheating, could be a flaky temp transmitter. Second, go to a 180 thermostat, I know it sounds crazy, but it will give the coolant more time in the radiator to cool down. The temp slowly creeping up is an indication of the coolant not getting cooled down enuff in the radiator. I've seen that happen a lot when folks pull the thermostat out in the desert areas. HTH.

[baz]

have you changed the sender unit for a new one ? it might be bad and just keeps on rising !!
try testing the temp with a thermo couple (most digi multi meters have one these days ) it might just be right

[opelbits]

What exactly are the overheating symptoms? Only while sitting idling? Only when at speed under load? Or both/anytime?

Mine used to slowly creep up while driving, but rerouting of fuel lines has eliminated that. However, if I let it sit and idle long enough, it will overheat. Sitting in traffic is nerve wracking, but it never gets hot while driving.

What kind of air filtration/snorkel are you using? This is more of a consideration when sitting in traffic, but if it's a carb top filter (K&N type), then it is drawing in not only hot under hood air, but the hot underhood air may be getting pulled up front thru the old (now unblocked) snorkel hole in the radiator support panel. Radiators don't work so well when they pull in 150 dgree + air.

[blancojp]

Thanks all for your help but I found the problem, at last!!!!
The head gasket had a few minor flaws like missing holes, etc.
Now that the engine is back together, it has been running at 1750 Rpm for the past two hours and the temp does not go higher than 190 degrees. That's with plain water in the radiator, a 160 degree thermostat and the fan without a shroud. The fan is approx. 3/4" away from the radiator

[namba209]

JB, that's great news. It's amazing what a little restriction will cause in a cooling system. Still running at 190, though indicates you could use the higher 180 thermostat and it should stay at that temp.

[tomking]

I have a fan shroud if you need one.

[Tru-Craft]

Otto posted this:

Originally Posted by tekenaar Originally e-mailed to me by "RallyBob" Legere I have found that by simply adding a couple holes to the stock head gasket, I can lower the exhaust temps of #2 and #3 by about 150 degrees. I do this to all my Opel head gaskets, matter-of-factly. I cut two 3/8" holes at this area only. To locate these holes, lay the gasket on the head, and tap the gasket with a soft hammer right at the triangular-shaped water passage holes on either side of the head bolt hole beneath the center exhaust ports. Then in the center of these indentations you just made in the gasket, punch out the aforementioned 3/8" holes. I use a gasket punch.

[blancojp]

We don't use the 180 degree thermostat due to a few problems encountered in the past. When we finish any engine, we install it to the engine test stand and run it for about an hour to break in the cam, primary adjustments and so on. After this, we then install it in the car knowing the sucker runs and is almost ready to go.

This engine ran on the stand with no problems but the first hour of operation usualy makes the engine run a little hot but mellows out after a while. The head gasket was missing 3 cooling holes as compared to the old one we removed from the motor. We added the extra 3/8" cooling holes and put it all back together without a hitch. Car hit the 117HP mark at rear wheels using chevy pistons, ported head and intake, stock cam with 1.6 modified chevy rockers, a rochester 2-jet carb with twin #53 jets and dual exhaust.

Not too bad....

[BQS4]

JP;
I don't want to make this sound so simple, but, have you checked the radiator cap? All this sounds like a situation me and my Dad had a few years back. He had a Sportwagon that originally had a/c. We removed the a/c and buttoned everything back up, and the car started running hot, for no reason. We had the radiator cleaned, put in several different thermostats, water pumps and hoses, but, it wasn't till we swapped the radiator cap (which was the one set for the a/c) just for ha-ha's that it finally ran cool like it was supposed to.
JMTCW,
Gene

[tekenaar]

Originally Posted by BQS4 JP; I don't want to make this sound so simple, but, have you checked the radiator cap? All this sounds like a situation me and my Dad had a few years back. He had a Sportwagon that originally had a/c. We removed the a/c and buttoned everything back up, and the car started running hot, for no reason. We had the radiator leaned, put in several different thermostats, water pumps and hoses, but, it wasn't till we swapped the radiator cap (which was the one set for the a/c) just for ha-ha's that it finally ran cool like it was supposed to. JMTCW, Gene

So which side is it, conservative or progressive?

Anyway, thought lean was more of a carb mixture issue!

[GTJIM]

My mind put the "c" right there in front of _leaned!

Even the auto spell checker can't catch ones like that - We kneed Otto!

[tekenaar]

Originally Posted by GTJIM My mind put the "c" right there in front of _leaned! Even the auto spell checker can't catch ones like that - We kneed Otto!

Below the belt . . . not allowed in sparring, even if only in words!