Cooling problem
08-22-2011, 04:04 PM
#1
Burning Brakes
Thread Starter
Cooling problem
I have been having a cooling problem lately... I rebuilt the LT1 with a cam, new waterpump,thermostat, gaskets, the works.... Anyways I got the car running and have been driving it around just fine. I went to Long island and back with no problems (600+ miles round trip) The car has about 1900 miles on the new build currently. One day I was on my way home from work and I saw my temp gauge go to about 210 which is not normal as I run a 160 degree thermostat and the fans are tuned to kick at 180. In which on my trip it ran nice and cool probably 170ish. Anyways I stopped and opened the hood to check it out and then I revved the motor to about 1500 and held it for a min and then the temp gauge dropped back to like 170 so I figured the gauge screwed up a little. Then I get home and the car won't go below 210 and the gauge is still climbing... So I recheck the radiator and rebleed the air from the thermostat housing and still its overheating so I take the thermostat housing off and the water pump is completely empty.. So I fill it up put it all back together and rebleed the air and the car is cooling again and the radiator is filled fine. I got for a drive around to the block no problem, then I decide to go farther... the gauge starts to climb again and I take a right hand turn and the temp drops.. so I'm like must be the gauge so I keep going and the gauge works its way up to the red zone so I stop and there is coolant overflowing out of the reservoir all over the place. (the original 84' reservoir) So I make it home after an hour of driving and stopping. I pull the thermostat housing again and it's empty again... so I try everything again... Refill, This time I leave the thermostat out so it will circulate and maybe fill the air pockets there might be in the block... so I do this and the car idles around 200 degrees then comes down to about 180 and stays there... I put the thermostat back in and refill/bleed again and the car starts running cool just fine. I take it to work and back no problem. I go to leave for my girlfriends house and I stop b/c of a train going by and the temp starts creeping up again... what the hell is going on?!?!? I bought the water pump off ebay so think its a **** pump? This is killing me as I want to drive my Corvette! haha
08-22-2011, 04:39 PM
#4
Tech Contributor
Disappearing coolant and puking out the reservoir....Likely a blown head gasket or a cracked cylinder head. However...
I would start with the easy stuff first...
- Get some test strips from your favorite auto parts store and test the coolant for signs of exhaust gases. While not 100% perfect if the test is negative, a positive test says my above guess is correct.
- Check the thermostat for correct operation. Put it in a pan of water with a thermometer, turn the heat on high, and observe when the t-stat begins to open vs the rated temp. A 160* t-stat starts to open at 160* and is fully open around 175*
- Drain the coolant and pull the front cover off the water pump. You should not be able to turn the impeller by hand since it's driven off the cam gear (via another gear). If you can turn the impeller, the pump is bad.
I would start with the easy stuff first...
- Get some test strips from your favorite auto parts store and test the coolant for signs of exhaust gases. While not 100% perfect if the test is negative, a positive test says my above guess is correct.
- Check the thermostat for correct operation. Put it in a pan of water with a thermometer, turn the heat on high, and observe when the t-stat begins to open vs the rated temp. A 160* t-stat starts to open at 160* and is fully open around 175*
- Drain the coolant and pull the front cover off the water pump. You should not be able to turn the impeller by hand since it's driven off the cam gear (via another gear). If you can turn the impeller, the pump is bad.
08-22-2011, 10:36 PM
#5
Burning Brakes
Thread Starter
I'm not really sure if its disappearing as much as the car is overheating and causing the coolant to boil out... Why would it run fine for over 30 miles then all the sudden just start overheating again? I'll have to check and see though, can't hurt...
08-23-2011, 12:02 AM
#6
Tech Contributor
Another way to check for this is to pull the O2 sensors. They should be dark gray to black in color. If the sensor is very light gray or white, it's coolant related.
Last edited by 96GS#007; 08-23-2011 at 12:06 AM.
08-23-2011, 12:18 AM
#7
If not a blown headgasket or cracked head,
There is a chance the new ebay water pump may be at Fault.
The water pump impeller or fan blade inside may have lost its press fit on the steel driven shaft.
That allows the water pump impeller to wobble and slip instead.
Slow coolant flow or no coolant flow then.
I have never seen it happen that way on an LT-1.
But I have seen it on remanufacted water pumps for GM cars, Fords, & Dodge.
The plastic water pump impeller blades are the worst for letting go suddenly.
Sometimes the plastic blades snap off complete.
The water pumps made with a cast iron or billet steel aftermarket are best I think.
Check like the others said.
If no combustion leak is present in the cooling system,
Suspect the water pump.
If I recall correct,
You can remove the back cover like the old SBC non LT-1 pumps just the same.
Inspect the blades & if the impeller still has a tight press fit on the shaft or not.
There is a chance the new ebay water pump may be at Fault.
The water pump impeller or fan blade inside may have lost its press fit on the steel driven shaft.
That allows the water pump impeller to wobble and slip instead.
Slow coolant flow or no coolant flow then.
I have never seen it happen that way on an LT-1.
But I have seen it on remanufacted water pumps for GM cars, Fords, & Dodge.
The plastic water pump impeller blades are the worst for letting go suddenly.
Sometimes the plastic blades snap off complete.
The water pumps made with a cast iron or billet steel aftermarket are best I think.
Check like the others said.
If no combustion leak is present in the cooling system,
Suspect the water pump.
If I recall correct,
You can remove the back cover like the old SBC non LT-1 pumps just the same.
Inspect the blades & if the impeller still has a tight press fit on the shaft or not.
08-26-2011, 01:51 PM
#11
Burning Brakes
Thread Starter
Well i decided to eliminate the possibility of a water pump related problem so I purchased and installed a CSR electric pump. (wanted one anyways) and the problem still persists. I can drive it around the block just fine runs cool as crap, then you get back home and let it idle and the gauge starts to climb and doesn't stop.... Sounds like the gasket now. Even when I see the temp starts going over 210 I open the bleeder screw on the thermo housing and it hisses for a second then coolant pisses out.. I was kind of tempted to try this Blue Devil stuff. It supposedly fixes head gaskets. But I figured it's either that or the car will be sitting from now until next year before it's driven again and I JUST got it done... I want to drive it! haha What can it do? Clog my heater core? That doesn't bother me at all. Its a last ditch effort and I have known some people to have good luck with it. What do you guys think? Bottom line is heads are not coming off anytime this year. I'm just tired of working on the car... Think that stuff is worth a shot?
08-26-2011, 02:21 PM
#12
Burning Brakes
Well i decided to eliminate the possibility of a water pump related problem so I purchased and installed a CSR electric pump. (wanted one anyways) and the problem still persists. I can drive it around the block just fine runs cool as crap, then you get back home and let it idle and the gauge starts to climb and doesn't stop.... Sounds like the gasket now. Even when I see the temp starts going over 210 I open the bleeder screw on the thermo housing and it hisses for a second then coolant pisses out.. I was kind of tempted to try this Blue Devil stuff. It supposedly fixes head gaskets. But I figured it's either that or the car will be sitting from now until next year before it's driven again and I JUST got it done... I want to drive it! haha What can it do? Clog my heater core? That doesn't bother me at all. Its a last ditch effort and I have known some people to have good luck with it. What do you guys think? Bottom line is heads are not coming off anytime this year. I'm just tired of working on the car... Think that stuff is worth a shot?
- how about those test strips? negative I am assuming if you changed the water pump first?
Last edited by mistaben; 08-26-2011 at 02:26 PM.
08-26-2011, 02:24 PM
#13
Burning Brakes
When I've seen this happen in the past, it's because one of the cylinder heads is cracked. The aluminum heads can be really hard to diagnose since the aluminum has to get hot enough for the head to expand and open up the crack. Then the exhaust gases force the coolant out. When you shut the car down, the crack closes up pretty quickly and any residual coolant boils off in the cylinder and goes out the exhaust the next time you start the car. Since the crack closes up, no coolant gets into the oil.
Another way to check for this is to pull the O2 sensors. They should be dark gray to black in color. If the sensor is very light gray or white, it's coolant related.
Another way to check for this is to pull the O2 sensors. They should be dark gray to black in color. If the sensor is very light gray or white, it's coolant related.
if it were a cracked head could he get a shop to weld the crack closed? like if he had a set of aftermarket heads he wanted to keep?
I know you can get a set of similar stock OE heads relatively cheap from a junkyard...
08-26-2011, 02:31 PM
#14
Burning Brakes
Thread Starter
I'm going to be doing heads this winter. So they are not coming off until I am ready to do the heads... Otherwise the car will sit until then unless I decide to try the blue devil stuff.... I want a temp fix that will hold me off until the car is off the road in few months..
08-26-2011, 09:15 PM
#15
Tech Contributor
08-27-2011, 03:03 AM
#16
Burning Brakes
Thread Starter
Well I used the stuff and now it stays nice and cool while the thermostat is out. When idling the temps are right where they should be. When driving the temps go down to like 165-170 b/c there is no thermostat. But she runs great, pulls faster through the rpm's without the mechanical pump on there. I think i'll just drive her without the thermostat for the rest of the season (2ish months) then do the heads over the winter.
When I put the thermostat in she overheats within a few mins and coolant comes out of the overflow bottle...
When I put the thermostat in she overheats within a few mins and coolant comes out of the overflow bottle...
08-27-2011, 03:08 AM
#17
Burning Brakes
Well I used the stuff and now it stays nice and cool while the thermostat is out. When idling the temps are right where they should be. When driving the temps go down to like 165-170 b/c there is no thermostat. But she runs great, pulls faster through the rpm's without the mechanical pump on there. I think i'll just drive her without the thermostat for the rest of the season (2ish months) then do the heads over the winter.
When I put the thermostat in she overheats within a few mins and coolant comes out of the overflow bottle...
When I put the thermostat in she overheats within a few mins and coolant comes out of the overflow bottle...
good to see you found a temp fix at least.
08-27-2011, 03:28 AM
#18
Burning Brakes
Thread Starter
Well the thermostat was wide open when I pulled it out... Then when I set it aside I watched it slowly close as it cooled down.I'll have to boil water and find out for sure.
08-27-2011, 03:50 AM
#19
Race Director
It sounds like the miracle head-gasket sealer (Blue Devil) worked. At least for the time being. Head gaskets (especially when initially starting to fail) can be somewhat intermittent. They can be sealing sometimes but leak at others. This is most prevalent with alum heads and a cast iron block since those metals heat/expand at different rates.
I didn't recall (or read) if you replaced the heads (or removed them during the cam install). But, I have to assume a head gasket is/was your issue. I don't buy removing your thermostat cured the problem if you also treated it with Blue Devil at the same time. Since the stat was visually moving, it seems more likely you sealed a smallish leak.
If you pulled the heads and didn't retorque, maybe you should do that. Or, if you reused head bolts, maybe that's the problem.
I didn't recall (or read) if you replaced the heads (or removed them during the cam install). But, I have to assume a head gasket is/was your issue. I don't buy removing your thermostat cured the problem if you also treated it with Blue Devil at the same time. Since the stat was visually moving, it seems more likely you sealed a smallish leak.
If you pulled the heads and didn't retorque, maybe you should do that. Or, if you reused head bolts, maybe that's the problem.
08-27-2011, 04:12 AM
#20
Burning Brakes
It sounds like the miracle head-gasket sealer (Blue Devil) worked. At least for the time being. Head gaskets (especially when initially starting to fail) can be somewhat intermittent. They can be sealing sometimes but leak at others. This is most prevalent with alum heads and a cast iron block since those metals heat/expand at different rates.
I didn't recall (or read) if you replaced the heads (or removed them during the cam install). But, I have to assume a head gasket is/was your issue. I don't buy removing your thermostat cured the problem if you also treated it with Blue Devil at the same time. Since the stat was visually moving, it seems more likely you sealed a smallish leak.
If you pulled the heads and didn't retorque, maybe you should do that. Or, if you reused head bolts, maybe that's the problem.
I didn't recall (or read) if you replaced the heads (or removed them during the cam install). But, I have to assume a head gasket is/was your issue. I don't buy removing your thermostat cured the problem if you also treated it with Blue Devil at the same time. Since the stat was visually moving, it seems more likely you sealed a smallish leak.
If you pulled the heads and didn't retorque, maybe you should do that. Or, if you reused head bolts, maybe that's the problem.
