My 72 GT is Overheating

[Richard117]

My GT has been overheating at times during the summer months. I have had the radiator flushed out and installed a 160 degree thermostat. There has been no improvement. I am now considering installing a new radiator, recoring the old radiator, or installing an electric fan. Any advise would be appreciated. Richard

[markandson]

Have you ever replaced the water pump, possible that the fins on the impeller are corroded and maybe gone. Also, make sure belt is not slipping.

[wrangler]

I recently went thru the same and ended up having a new core put in my radiator as well. It solved the problems but did cost a little over $200. On the plus side, it has larger tubes than the original.

[jordan]

Having a thermostat of that low a temperature may actually increase engine idle temperatures because the hot coolant does not remain in the radiator long enough to cool to the radiator's maximum efficiency.

[baronbors]

Are you running a fan shroud- made a world of difference in the
Houston heat.

[N61WP]

A quick fix that might help you get by is adding a bottle of Redline's Water Wetter. It works.
Jc

[GTJIM]

Make very sure that the ignition is not retarded at the lower revs - that puts the temps up quickly! Sometimes the ignition is retarded to stop pinkig at higher revs and this moves back the initial advance too much. The cure is to "recurve" the distributor to limit the centripital advance allowing more initial advance while controlling total advance. The vacuum advance is also needed at idle revs to "suck" enough advance in at low revs and high vacuum.

[Richard117]

I do have a shroud. I will check out all your ideas and hopefully will get the problem resollved. Richard

[Turbo X]

Are you loosing water if so , make sure your radiator cap is in good condition and set for 10 to 13lbs, and put a recovery system in. check for oil in your water, if so you have a cracked head, or head gasket could be leaking,, do a compassion test..

[Richard117]

Not losing coolant. Thanks for your help. Richard

[duvel]

I had a blocked channel from the thermostat to the pump.I have opened both and used pressed air to unblock that.

[Richard117]

Thanks again for all your help. Has anyone had any luck with an electric fan. I talked with a couple owners at the OMC Picnic who felt they had taken care of their problems with an electric fan. I talked with another GT owner who said they were only helpful at lower speeds and not when you were on the freeway traveling at 70 MPH. Richard

[Turbo X]

by what your saying is that it over heats when your at hi way speeds?
or only when idling?
Before I spent the money on a electric fan ,I would have a radiator shop do a flow check on it to see if its plugged.

[soybean]

Richard117, I have a three core, or row, radiator in my Gt along with an electric fan with a thermostat, new thermostat and water pump, along with a catch can. In stop and go situations during the summer the fan cuts on. Once you reach highway speeds it quits. During the cooler months it hardly runs at all. One thing that puzzled me in the beginning was I changed thermostats with one from a local parts store and it was running hot. I tried everything I could think of and nothing worked. Then I ordered a thermostat from OGTS and installed it. No problems since.
I have no clue as to what the difference could be. Both opened at the same temerature when I boiled them in a pot on the stove. The only thing I can think of is the original has a slightly larger diameter opening that the aftermarket. On the other side one of our Club members (Carolina Opels), has done away with his fan altogether and is just running an electric fan as a puller instead of a pusher. Do a search for "Electric Fans", and you should come up with a bunch of good information. Quite a few have gone this route. Sorry for the long winded litany, just my experiences. HTH, Jarrell

[petrieopel]

I'm not using the stock fan and use a Summit Racing electric fan as a pusher. It works great and have no overheating problems.

[soybean]

Just another thought. Have you checked your timing? If it's off a lot it could acerbate the heating. Jarrell , (running out of ideas) :o

[opeldean]

Originally Posted by Richard117 Thanks again for all your help. Has anyone had any luck with an electric fan. I talked with a couple owners at the OMC Picnic who felt they had taken care of their problems with an electric fan. I talked with another GT owner who said they were only helpful at lower speeds and not when you were on the freeway traveling at 70 MPH. Richard

I was told by greensmurf 20, that any fan is not a factor at highway speeds,
so if you are overheating on the highway,you have a waterpump,radiator or coolant flow issue.

question:

I have been running a bit hot too this summer in the 95 degee days, i have been losing coolant after i fill it, it spills on the parking lot after a hot drive, so i guess i may have a cap issue?

I have switched to a 192 degree thermostat, trying to keep the coolant longer in the radiator, I dont know if that was the right thing to do.

My gauge reads at over 1/2 on an 80 degree day, on a 95-100 degree day I read at 2/3 to 3/4.no steam of boil over yet

[soybean]

Originally Posted by opeldean question: I have been running a bit hot too this summer in the 95 degee days, i have been losing coolant after i fill it, it spills on the parking lot after a hot drive, so i guess i may have a cap issue? I have switched to a 192 degree thermostat, trying to keep the coolant longer in the radiator, I dont know if that was the right thing to do. My gauge reads at over 1/2 on an 80 degree day, on a 95-100 degree day I read at 2/3 to 3/4.no steam of boil over yet

The cap is supposed to be 13 to 15 Psi I believe. The thermostat 180 degrees. The spillage is why I put in a catch can, so when it cooled it would draw the water/anti-freeze back into the radiator.Yesterday was 95 with heat index of 100+ and it stayed normal (1/2 way mark) until stoplights, then it went up to 3/4. But by that time the fan had cut on. Maybe its just me, but this has been a hotter than normal summer too. Jarrell

[GTJIM]

It is critical to keep the cooling system FULL of fluid. As the system heats up the liquid expands - and dumps out onto the ground. Unless a "catch can" is attached to the overflow pipe and the correct type of radiator cap is fitted only air can be drawn back into the system to replace this lost fluid.
This cap has a second seal in it which allows the cooling fluid that expands into the catch can to be drawn back into the radiator when things cool down a bit or the car is turned of and stands for a while.
The moment air enters the cooling system its ability to cool is reduced as the air bubbles formed in the coolant act as insulators between the cylinder walls and the coolant. Adding a "wetting" agent helps keep the coolant intimately in contact with the cylinder walls too.
So the addition of a catch can and wetting agent can greatly improve cooling.
All cooling is limited by the actual capacity of the radiator to transfer heat from the coolant to the air passing through the fins. Hence the recoring with three or four rows of cooling tubes; the addition of finer finning and the addition of a high capacity electric fan.
GT cooling is marginal in stock form due to the small cross-section area of the radiator so upgrades need to be made in air flow and thickness of the core.

[namba209]

Here's what I've been able to figure out on electric fans, or viscous drive fans that are temp controlled. All this is based on my motorhomes operations so I'll give some idea of where it's at. First off, I have huge radiators for the 460 and 454 engines, and huge grill openings and the radiators have shrouds and they are the only opening into the engine compartment from the front. Now, even at highway speeds the fans will come on when the temp gets too high. When I lost my fan drive on a road trip, I found that I could keep the engine from overheating by going a constant 45 MPH. This was across the desert on I-10 from LA to Vegas in the middle of summer. Anything more or less than 45 would show an increase in temp on the gage. Using my vast? experience on airflow, I came to the conclusion based on a really simple theory, only so much air will flow through a radiator at a given speed using vehicle speed to get the air flow, to increase the air flow through the radiator another means is needed to increase the airflow, hence the fans. I also came to the conclusion that going faster did not increase the air flow because of something causing back pressure at the rear of the radiator limiting the air flow through the radiator, or maybe the radiator opening or face is not large enuff to allow more air flow through it without assistance. Whatever it is, there are times when freeway speeds are not sufficient to cool down the fluid in the radiator so other means if increasing the air flow is needed. O.K. long winded and tongue-in-cheek, but you get the idea, I hope.

Now with all that being said, I will concur that the flow through the radiator and engine should be checked for restriction on Richard's GT, and maybe a 3 row should be put it if he doesn't have one. All the other ideas are also valid, but without good total coolant flow and air flow, the problem will persist.

[Richard117]

Thanks for everyone's help. I think I have enough information to rectify the problem. I will start out with a good radiator shop and have them check out the coolant flow and go from there. Richard