LT1 Overheating, can't find problem?!
Thread Starter
Staging Lane
Joined: Jul 2011
Posts: 68
Likes: 0
From: Minneapolis, MN
For how intricately the cooling system is, the procedure is simple. Coolant simply circulates throught the system to keep everything cool. Since the radiator hose is cold, your not getting complete circulation. So if you say your waterpump is working then you definatly have a clog somewhere, or something. Even though the waterpump appears to be working and usually you loose the WP gasket before the pump actually fails, I wouldnt count it out as the culprit.
But I would start with the cold hose and put some time in.
But I would start with the cold hose and put some time in.
Exactly how much coolant did you drain? If you are sure the pump is working and the entire system has no air and contains approx 16 quarts of coolant then there is a clog somewhere. If I were you I'd drain both the radiator and the block and measure exactly how much coolant is in the system. Also, there is no reason to jack the car up in order to bleed it. The engine is already tilted and the system is designed to bleed at the crucial points.
Last edited by SS RRR; Jan 28, 2013 at 07:45 AM.
Launching!
Joined: Oct 2011
Posts: 284
Likes: 0
From: Dixon, IL
I blew water through all of the hoses when I had the radiator removed to be flushed. None of the hoses are clogged or leaking, and they were replaced a few months ago. The engine still overheats after idling for 15-20 minutes on the driveway and the radiator is still ice cold. The water pump is working just fine, as it was spinning when I took the plate off and started the engine up to check.
Teching In
Joined: Feb 2012
Posts: 42
Likes: 0
From: Treasure Coast, Florida
Here is my 2 cents.....
When you are bleeding the system you should have the heat on max and and the hottest setting as mentioned above #22.
Another issue I have seen in the past is putting the wrong waterpump on, it needs to spin the right way.
I had a Roadmaster LT1 and the little foot at the bottom of the T-stat broke off and blocked the passage.
I have read on another forum of testing the waterpump by pulling off one of the heater hoses and starting the car to see if it blows enough water out. "Spinning" when cranking or idling doesnt mean good, it may not be keeping up due to worn blades.
I went through this before and found out the guy before me put block sealer in my engine and sold me the car with blown head gaskets, exhaust in the cooling system.
Good luck
When you are bleeding the system you should have the heat on max and and the hottest setting as mentioned above #22.
Another issue I have seen in the past is putting the wrong waterpump on, it needs to spin the right way.
I had a Roadmaster LT1 and the little foot at the bottom of the T-stat broke off and blocked the passage.
I have read on another forum of testing the waterpump by pulling off one of the heater hoses and starting the car to see if it blows enough water out. "Spinning" when cranking or idling doesnt mean good, it may not be keeping up due to worn blades.
I went through this before and found out the guy before me put block sealer in my engine and sold me the car with blown head gaskets, exhaust in the cooling system.
Good luck
Staging Lane
Joined: Dec 2012
Posts: 55
Likes: 0
^^^I don't understand why you say the heat should be on max... There is no shut off valve in the F-body and coolant flows through the heater core whenever the car is running. The only thing the temperature control **** does is open or shut the door that controls air blowing through the heater core.
Teching In
Joined: Feb 2012
Posts: 42
Likes: 0
From: Treasure Coast, Florida
^^^I don't understand why you say the heat should be on max... There is no shut off valve in the F-body and coolant flows through the heater core whenever the car is running. The only thing the temperature control **** does is open or shut the door that controls air blowing through the heater core.
Here is a link that should help you out, I say go through the steps and see what your missing. The T-stat you should have in the car is this one http://shbox.com/1/tstat.jpg . This is the bleeding proceedure and some trouble shooting ideas http://shbox.com/1/4th_gen_tech2.html#radflush , Did you flush the heater core? http://shbox.com/1/4th_gen_tech2.html#heaterflush
Look around his site, there is a lot of useful info there.
This link shows where the hot hoses are and the cold ones, this should help you find the blockage http://shbox.com/1/95-97_hoses.jpg and for the heater hoses http://shbox.com/1/heater_hoses.jpg
Hope this helps....
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Staging Lane
Joined: Jul 2011
Posts: 68
Likes: 0
From: Minneapolis, MN
Well. I have had the car sitting for 3 weeks now untouched out of fustration. Just yesterday I put a new thermostat in. 3 batteries worth of cranking later she finally started in 5 degree weather. I let her idle on the driveway for no more than 8 minutes and she was already at 220 degrees so I shut her off knowing this wasn't going anywhere fun. The coolant in it is fresh. The fans work. There are no leaks anywhere. The engine feels hot yet the radiator and hoses are still cold. I have used a hand pump to bleed out any air pockets that would be in there. The pressure stays around 14psi so there isn't a blown head gasket or anything otherwise the pressure would go sky high. I'm getting really fustrated with this. I took the front plate off the water pump and it turns when the engine is running. I'm going to remove the thermostat and run the engine without it and see if the radiator will heat up at all and hopefully I can get coolant flowing. Any help?!?
Aluminum heads cannot be magnafluxed. They can however be pressure tested. Don't understand what you mean about using a hand pump to bleed air pockets. You're not answering questions either so there's really no way to help you. Good luck.
Why don't you remove the t stat and run it? Your heads are fine, as stated there IS NO COOLANT GOING THROUGH YOUR RADIATOR. Fix that issue first, if running without a stat won't get water moving through the radiator, then change the water pump. Put a garden hose on the top hose of the radiator and verify it comes out the bottom too.
Thread Starter
Staging Lane
Joined: Jul 2011
Posts: 68
Likes: 0
From: Minneapolis, MN
Radiator pressure tester, has a psi gauge and a hand pump.
Thread Starter
Staging Lane
Joined: Jul 2011
Posts: 68
Likes: 0
From: Minneapolis, MN
I will. I replaced the pass head gasket in November and the whole gasket actually shifted towards the rear of the engine. I'm afraid that might've happend again, if not I either cracked the head or the other usuals.
Thread Starter
Staging Lane
Joined: Jul 2011
Posts: 68
Likes: 0
From: Minneapolis, MN
Why don't you remove the t stat and run it? Your heads are fine, as stated there IS NO COOLANT GOING THROUGH YOUR RADIATOR. Fix that issue first, if running without a stat won't get water moving through the radiator, then change the water pump. Put a garden hose on the top hose of the radiator and verify it comes out the bottom too.
Thread Starter
Staging Lane
Joined: Jul 2011
Posts: 68
Likes: 0
From: Minneapolis, MN
In the middle of pulling both heads off. Before I did, I ran the car around the block for a bit and there's a good amount of blue smoke coming out the tail and you can smell the coolant. The radiator loses coolant after every run, and I pull the dip stick and the oil is a milky caramel, so water is getting in somehow, so one of my head gaskets blew or cracked a head 
On The Tree
Joined: May 2010
Posts: 155
Likes: 0
From: Vancouver,WA
I had a freeze plug goes year's ago. The crack was small enough to were it would boil off before hitting the ground. So leaks were hard to find. Plus just because you have new hoses, doesn't mean the restriction cant be more internal. Have you done a coolant pressure test?
Teching In
Joined: Feb 2013
Posts: 7
Likes: 0
From: Slc, utah
So you only replaced one head gasket? To me that's a big no no. If you do head gaskets always do both. Sure you can get away with it but in most cases if one is bad they both are. That and you never now if someone else before you didn't put a stock one back in or put a perf in.