overheating!!!! HELP!!!!

[69camarokid]

i have a 95 trans am lt1/t56 in a 69 camaro.
I had a blown head gasket. replaced it, head was checked out, all that fun jazz.

Got the whole engine back together this weekend, everything was replaced. I blead all the air out of the engine and have no coolant leaks, the fans work fine, but still i overheat past 250 degrees in just a few minutes time. How can this be. what could be causing this?

Any help or ideas at all would be greatly helpful, thanks

[Vegas69]

Sounds like an air pocket in the engine.....

[69camarokid]

how do i get rid of an air pocket if it is one

[Vegas69]

Take the radiator cap off and put the front tires on some 2x4's. If the temp gauge rises quickly it has to be an air pocket. I'd bring it up to temp with the cap off. Your upper radiator hose should be hot and coolant will be flowing through your radiator. The air pocket will work it's way out the radiator cap fill hole and you should be able to achieve a temp around your t stat. Then top it off and put on your radiator cap.

[Twentyover]

stuck stat?

[69camarokid]

how can i test to see if the thermostat is stuck

[69camarokid]

well, the thermostat seemed to be just fine, but i replaced it just to play it safe. when i took off radiator cap i noticed my radiator was almost empty. I had filled it before i left this morning so my overheating must have been caused by an ampty radiator. so the water/coolant must have leaked out somehow. or so i thought.

So i refilled the radiator, turned on the car, new thermostat and all. it sat ther at idle and within a few minutes it was past 200 and climbing. the 180 thermostat made no difference. I checked under the car.... no leaks of any kinds? the fans run full time. I dont understand how this overheating is happening!!!!

any other ideas?

[tumper93]

LT1's are hard to bleed all the air out unless you can pull a vacuum on the system when it is dry. The way I bleed them before I had the tool was to fill the radiator or surge tank until full, then open the bleeders until coolant comes out, sometimes it won't but the coolant level should drop. Close the bleeders and start the engine then open the bleeder at the water pump and see if any air escapes if only coolant come out, close bleeder, rev the motor to about 2k and even if the temp gets kind of high...say around 240 it will be okay as the bubble should quickly purge. Always seems that it gets kinda warm before it lets go but does do it with RPM up...it won''t if left at an idle.

[69camarokid]

LT1's are hard to bleed all the air out unless you can pull a vacuum on the system when it is dry. The way I bleed them before I had the tool was to fill the radiator or surge tank until full, then open the bleeders until coolant comes out, sometimes it won't but the coolant level should drop. Close the bleeders and start the engine then open the bleeder at the water pump and see if any air escapes if only coolant come out, close bleeder, rev the motor to about 2k and even if the temp gets kind of high...say around 240 it will be okay as the bubble should quickly purge. Always seems that it gets kinda warm before it lets go but does do it with RPM up...it won''t if left at an idle.

tried this, but to no avail. The car still over heats.
dont know what to do. I never had this problem before
Ive heard there is an impellor in the water pump and that if it is lined up incorrectly then it would cause overheating. anyone heard of this or know anything about it?

[tumper93]

The impeller cannot be misaligned, the optispark on older lt1's could though because of how it connected to the gear.

[69camarokid]

The impeller cannot be misaligned, the optispark on older lt1's could though because of how it connected to the gear.

perhaps i misunderstood this, but your saying the impellor is ok, but my opti could be misaligned. what does mis aligning my opti have to do with overheating. wouldnt that just affect spark?

or were you just letting me know so i know that the water pump could not be the problem.

[tumper93]

perhaps i misunderstood this, but your saying the impellor is ok, but my opti could be misaligned. what does mis aligning my opti have to do with overheating. wouldnt that just affect spark?

or were you just letting me know so i know that the water pump could not be the problem.

What pump isn't the problem.

[67 ls1 vert]

Do you see water rushing by with the cap off the radiator with the water temp up at operating temp? If not, your radiator may need to be repaired.

Also, with the car running and the cap on, wear gloves and try to squeeze the upper hose. You might get the air bubble to dislodge.
Good luck.

[E.rodz]

try this one super easy trick while the engine is running and the cap open use a shop vac and lightly put over the rad. opening don't seal it up completly just put enough seal to suck the air bubble to the radiator.i think this should work just fine.had this problem with an ls conversion and had the car on jack stands.this trick worked in just a couple of seconds.

[130fe]

Like the others have said, it sounds like an air pocket. Are your fans coming on at the programmed temperature? Do they run all of the time or when they are "supposed" to come on. I never had any luck using the bleeder screws so I just removed them totally. The best way I have found to avoid air pockets in my LT1 is to fill the engine block (with coolant) through the upper hose (the one right below the throttle body on top of the water pump). Just disconnect it from the upper radiator hose barb and then reconnect it to the radiator when the block is full. I fill it through the radiator hose and take my time allowing all of the air to "burp" out as I fill it and then fill the radiator to the top. See if that works for you and post up your results.

[68BNUT]

This may be dumb, but Ive done it before. Did you put the gear drive piece (whatever its called) that drives the water pump back in after you put it all back together? I replaced my water pump and left that on the old one, took me all dang day to figure it out!!

[69camarokid]

so i didnt pull the water pump, but i removed my intake tubing and was able to see down behind the water pump. My shaft is spinning when the car is on. Is it possible that it could be spinning and not work.
OR does the fact that the shaft is spinning mean that my water pump is ok and that it is somehting else?

[69camarokid]

Like the others have said, it sounds like an air pocket. Are your fans coming on at the programmed temperature? Do they run all of the time or when they are "supposed" to come on. I never had any luck using the bleeder screws so I just removed them totally. The best way I have found to avoid air pockets in my LT1 is to fill the engine block (with coolant) through the upper hose (the one right below the throttle body on top of the water pump). Just disconnect it from the upper radiator hose barb and then reconnect it to the radiator when the block is full. I fill it through the radiator hose and take my time allowing all of the air to "burp" out as I fill it and then fill the radiator to the top. See if that works for you and post up your results.

The fans run full time and come one everytime the car starts, so no issues there. I have bledd the car about three times now with the bleeder screw, if it is indeed an air pocket then this has not got it out. Never had this issue before.

Ill try your bleeding idea tonight when i get home from school.
I rebuilt the top end because of a blown head gasket due to overheating becuase the fans never came on, bad power wire to fans. I had the heads pressure tested and they were good. Could the rebuilding of the topend somehow have caused an overheating issue? the radiator adn water pump, and thermostat are all brand new as well.

[aany001]

is the belt routing proper and spinning the water pump in the correct direction??? these LT1s have reverse coolant flow.Hope this helps

[130fe]

camarokid, you say the fans come on right away after you start. Do you have a check engine light on? The PCM defaults to fans on as soon as it has a trouble code. Do you have the PCM controlling the fans? Have you had it scanned to see if the PCM is reading the same temperature as the gauge? The PCM normally activates the fan off of the sensor on the front of the water pump. Just trying to give you other things to think about.