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Discussion Starter · #1 ·
Overheating Problem

Having just put the engine back together with a new rad, thermostat, hoses, and new coolant I am having a problem with the engine overheating when at the idle, but she cools right down when on the move. In fact it cools too much.

There is the possibility that the thermostat is faulty, but any other suggestions?
 

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I just put mine together a couple months ago and it ran a bit higher at times but has now, at about 1000 miles on the engine, started to run more consitently at the same temp (one notch under half due to a 160 degree thermostat). I think when the engines are new and tight they tend to run warmer. I also used 10w/30 for the first couple oil changes (now 10w/40). Also make sure the radiator is topped up to get air out of the system.
My $.02
 

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Discussion Starter · #3 ·
Thanks Bosco, however at idle, mine heats up to just a notch below the red line! But once I put her in gear and move, it drops down. I'll try a different oil viscosity.
 

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I've always found that newly rebuilt engines run a bit hot.

But, I have one question to ask you, do you have a fan shroud in place? A classic example of not having a shroud is overheating at idle or slow speeds, when the airflow through the radiator is reduced or nonexistant. Without the shroud, the fan doesn't work nearly as efficiently at a standstill or slow speeds.

HTH
Bob
 

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Rallybob now that you mention fan shrouds, who made the fiberglass aftermarket one? I was curious becouse it seems pretty nice and had to wonder if the mold was still around. Is this a C & R part?
 

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I remember seeing a fiberglass version of a shroud, but don't recall ever seeing a mold for one. So the mold either was lost/destroyed or the part came from Germany.
 

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Discussion Starter · #7 ·
Rallybob, no I don't have a fan shroud. The car never came with one so I never thought to replace it when I rebuilt the engine. This might be the thing I look for at Carlisle.

Thanks for the info.
 

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Graham,

Too bad I'm not going (SOB!!), as I have several spares. If you REALLY need one before you leave, I could throw it on a bus. Or maybe you could install an electric fan, as I think that is a worthwhile thing to do in any event.

Have a great time, take lots of pics, and post them here so I can see what I missed. Especially of the people there. At OMC the cars were nice, but it was TERRIFIC to finally put a face to a name.

I think I have talked myself (and Myrna was an easy sell, as she was keen to go to Carlisle this year if I wasn't so busy at work) to go to go Tacoma in July. A bit far to drive from Ottawa, but a heck of a lot closer to Calgary
 

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Here in Las Vegas it's already getting hot enough to start wondering about cooling systems. I have been thinking of an electric fan and would like to use one (as a pusher) in conjunction with my mechanical fan (and shroud). Would this combination work better than stock or would whatever restriction in airflow it creates offset the advantage of the extra fan?? I would be looking at fans that fit the front of the radiator without modification.....so maybe a 12" or 10" fan at most. We have long stop lights here and on 100++ day with heavy traffic they can become an adventure.....

This is its first full summer on the road and rather than wait to see how bad it can get I'm looking for some temperature containment ideas now.
 

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It gets warm in BC too

Hi Keith,,, my GT is still in pieces but I'll start assembly when I receive and install my new pistons. Would you be interested in selling and sending a shroud on the bus to the West? I temporarily helped my heating problem with a cooler thermostat, but the temperature was still too high for my liking.

Lonnie
 

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Lonnie,

Sure. Today it's NOT so warm in Calgary. Yesterday Myrna and I went for a mountain bike ride on Nose Hill, and I was wearing shorts and a T-shirt. This morning, it's just below freezing, and about 2 inches of SNOW has fallen, and more is coming down. Not enough to collect on the streets, but it's accumulating on the grass. Probably a good thing, as we have been having a drought, and the moisture is much needed (especially on my recently aerated lawn).

The shrouds are in the rear of my SportWagon, shown below. Give me a couple of days for the snow to melt, and I'll dig them out and make sure that they are GT shrouds, and not all Manta/Ascona shrouds. I have my GT shroud to compare, but I think they are a bit different. I have four, I think, so at least one should be a GT
 

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Opeler
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Screwy weather patterns

We are overcast but warm; I've just come in from outside. I just finished weeding so I can transplant a few more grapes (but of course I had to prioritize and finish the opel's engine lifting beam first). I picked up another mild sunburn riding my roadbike yesterday. I think we will be confusing our friends from the States with the contrast in weather conditions. I can't see any more mountain peaks with snow so I think we are in for a hotter summer than even last year.

Let me know how much to send you for the shroud. We can chat on private e-mail. Lonnie
 

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CIH cooling tips

Graham said:
Rallybob, no I don't have a fan shroud. The car never came with one so I never thought to replace it when I rebuilt the engine. This might be the thing I look for at Carlisle.

Thanks for the info.
This car was designed for Germany . . . you know, high-speed Autobahns and such. The cooling system is adequate in those places, but is merely marginal in the higher mean temperature climates like Texas, Arizona and Nevada. Regardless, NEVER run without a fan shroud, as Bob said, and don't run carb without the heat shield and phenolic 3/16" spacer, especially if still running the "joined" stock manifold setup.

Something I've found VERY EFFECTIVE for those of us running Opels in the hotter climes. I run a 160 deg. T-stat and a coolant mix of 25% (3 parts water, 1 part antifreeze) with a "water wetter" added in proper proportion in all my CIH engines down here, modified or stock.

Seems to work even in the hottest days in traffic . . . usually doesn't get over one notch over center even in "stop and go" traffic. My performance engines do have 3-cores in them, but all my stock or close to stock engines have just pressure and flow tested, cleaned "stock" radiators.

NONE of mine are run without fan shrouds or carb heat shields, even where I had to special fabricate one for other than "stock" carb installations. It's just that important! And, if rebuilding your engine or just doing some head work, remember Bob's tip about the two extra 3/8" coolant holes in the head gasket!
 

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tekenaar said:
Something I've found VERY EFFECTIVE for those of us running Opels in the hotter climes. I run a 160 deg. T-stat and a coolant mix of 25% (3 parts water, 1 part antifreeze) with a "water wetter" added in proper proportion in all my CIH engines down here, modified or stock.
One common misconception about Water Wetter is that it improves the cooling capacity of your cooling system. You can't get much better cooling characteristics than straight water, but running straight water will corrode your water pump and just about every piece of metal it touches, as well as freeze as soon as the temp dips below 32. To combat both of these problem, traditional anti-freeze is used. If a performance minded individual is not worried about freezing temps, and wants every drop of thermal capacity then straight water should be used. The proper amount of Water Wetter is then added to prevent corrosion.

Otto's formula is a good year-round cocktail for Texas. Us northerners (who saw freezing temps last week) have to run 50/50 (anti-freeze/water) either year round, or go through the seasonal flush-n-fill.
 

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Water Wetter..... does just what its name implies. It breaks the surface tension of the water to prevent nucleate boiling, where the gas bubble adheres to the surface of the steel preventing the cooling liquid from remaking contact with the steel surface. That is boiling on the molecular level. It also has a water pump lubricant and some corrison inhibitors. But its primary function is as a surfactant. If you read the directions it says it works best with straight water, antifreeze reduces its effectiveness. Thats why it has the corrison inhibitors and water pump lubricant, since they are assuming the user will not use it with antifreeze which has those additives.

And yes water has a higher heat carring capacity (in BTUs per pound mass) than any of the glycol based mixtures. EthyleneGlycol just has a higher boiling temperature than water.

Paul
 

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Mayby the indicator is cheeting. It often hapenes so i the old opels. The reason is: broken voltage stabilisator in the daschboard.
 

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Paul said:
It breaks the surface tension of the water to prevent nucleate boiling
So basically you are saying that it is soap? :D

*please please please, anyone that is reading this don't interpret this as being able to use Dawn as a cheap substitute. Please.

I was always told by the Mustang boy-racers that WW improved the cooling capacity, and the old-school hot-rodders only gave WW credit for lubrication and corrosion inhibition. I of course believed the old-timers, but it turns out they both were right.

Either way, it's the right stuff for a hot climate (without the possibility of freezing).
 

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Yes soap is a surfactant. Its often used by farmers who mix it with herbicides.......

If you have ever watched a pot of water while you are waiting for it to boil, you have seen an example of nucleate boiling. The short story is... as the gas bubble forms, the bubble sticks to the surface of iron. At the localized area of the bubble, there is no contact between the liquid water and the steel, only contact between gas and steel. At this localized point, heat transfer is no longer via conduction, it is now via convection. Conduction is a far superior method of heat transfer. The presence of the gas bubbles forming on the surface of the iron in effect reduces the total area available to conduct heat transfer. Water wetter helps eliminate this phenomenon, thus improving cooling capacity.

The other side effect of nucleate boiling is the localized hot spots created in the area of the bubble. These hots spots can, in the right combination of circumstances, be a source of pre-ignition (Knock or detonation). Especially under race conditions.

Sorry to be so long winded.

Paul
 
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