strange overheating problem

[stockgp]

this is on my 92 vert with a 3.1.

 

i bought the car with an overheating problem. the guy told me it started overheating and he quit driving it. supposedly, he replaced the water pump and radiator, but who knows.

 

so, the odd thing is, the car won't always overheat. also, it won't always stay hot. usually, it will start to overheat, stay hot for a minute, then shoot back down to around 180 degrees. sometimes, depending on how long i drive, the car won't overheat at all. also, it may be my imagination, but it seems that when the car overheats, the hvac won't blow hot air. i know that was the case last night.

 

now, the only things i know it ISN"T is the head/intake gaskets and thermostat. i just replaced those yesterday and it's still overheating.

 

i've changed the t-stat three times now. each time, there has been NO coolant in the upper rad hose. i've had the coolant professionally flushed and filled, to no avail.

 

this is the last chance this car has. if i can't figure this out, i'm going to part the sorry sob out.

 

help me save a decent car

[Regal_GS_1989]

Hrmmm.... Cracked head maybe? Does there seem to be any consistant air bubbles in the coolant reservoir?

[stockgp]

it's hard to see into the reservoir. if the head was cracked, wouldn't the oil and coolant be mixing?

[Crazy K]

TEMPORARY SOLUTION: drill the Tstat. You have air trapped continually behind the T-stat.

 

Don't worry. my 93 did this too.... turns out it was a missing hose clamp left off by a previous mechanic... this was one of the clamps on the throttle body heater thingamajig.

 

Solution: locate and repair cooling system leak.

[stockgp]

how did i know you'd be in on this?

 

i'll give it a shot. thanks, ken

[stockgp]

i took the tstat out and ran the car for a while. it didn't overheat, but it still seems to tun a bit warm for having no stat at all.

 

the needle on the temp gauge settled in right between the 2 and the 0 in 200.

 

 

[stockgp]

went for a longer ride this time. still got hot enough to turn on the check gauges light and boil the coolant.

 

any other ideas?

[Crazy K]

leave the Tstat in!!!! you could be letting coolant flow TOO fast with too little pressure.

 

ie the engine gets hot enough to force all the coolant out.

 

drill the Tstat and test drive.

 

btw... do you have regular mix in the car? or Water?

[rockfangd]

does it lose coolant? (besides when it overheats)

Have you done a pressure test to pressurize the system?

If you run the car without the radiator cap does it bubble continously?

Have you bled the system with both bleed ports?

When it is running fine does the heat blow hot?

Does the exhaust smell sweet?

Hows the oil look?

Lots of questions lol. this can help alot

[stockgp]

ok, ken, will do. how big of a hole should i be drilling, though?

 

50/50 mix before the headgasket, more like 90% water now.

 

also, even with the tstat out, the upper rad hose is empty. i don't get it.

 

rockfangd,

 

it seems to be losing coolant now, though it wasn't before.

 

pressure test, no. i don't have the tools and i dind't have the guy that flushed the system do it.

 

while it was at the rad shop doing a block check, it did not bubble constantly.

 

bled the system several times with both bleed ports. however, the last few times i have tried, i've been unable to get anything to come out of the upper bleed port even as coolant is flowing back out of the neck.

 

heat is fine while the motor is running at normal op. and, during my test drives earlier, blowing hot as it was overheating, too. maybe not as hot as it should be, but it's hard to tell as hot as it is outside.

 

exhaust did not smell sweet yesterday after i did headgasket. perhaps does now, don't know.

 

oil was fine before head gasket blew say before yesterday. now, obviously has water in it. i am on my second oil change as of an hour ago to try to filter the water out.

[Crazy K]

? you just re-gasketed the engine? same heads?

 

under what type of circumstances does it get the hottest?

 

I would drill a 1/4 inch hole. no T-stat can shock the system too much.

[stockgp]

same head. after it was checked for warping.

 

it usually gets hot if i was on the highway for too long, or if i get off the highway and into slower traffic for a bit.

 

after the gasket, highway speeds seem to keep the temp under 180 with the tstat out.

[rockfangd]

my cadillac had the same problem and i believe it was a cracked head. What happens when you squeeze the lower radiator hose. I do not understand why there is no coolant at the upper hose

[stockgp]

ken, where exactly am i supposed to drill a hole 1/4"? the flange isn't nearly big enough to accommodate a 1/4" hole.

 

rockfangd, i'm not sure what you're looking for here. what do you want to happen when i squeeze the lower rad hose?

[rockfangd]

squeeze the lower radiator hose with the cap off, preferably engine slightly warm, Dont get cut or burned and just squeeze the lower radiator hose and see if air pushes out of the radiator or just antifreeze. Squeezing the lower radiator hose tends to help push any air up to the top

[Crazy K]

just a hole. In a pinch, you could jamb the T-stat open with a chunk of coathanger...

[stockgp]

i drilled about 1/8" hole and took it for a ride a little bit ago. didn't go over 180, but i'm not holding out hope that it won't still overheat.

 

rockfangd, only coolant comes out the neck when i squeze the lower rad hose.

 

i have to figure there is some kind of blockage in the radiator. that's the only reason i can see that i can't get any coolant into the upper rad hose. bought a new one from rockauto a few minutes ago.

 

if this doesn't fix the problem, i'm parting the car out. i have a good bit of brand new weatherstripping to sell if so.

[rockfangd]

thats cool. i hope a new radiator fixes the problem