92 GASE 3.3L cooling problem

[jbmx4life]

Just recently started to have problems with the cooling system on my car. At highway speeds the temperature just keeps climbing (220+) and the only way to keep it down/stable is to turn the heater on hot and full blast w/ rolling the windows down. When I had the car sitting at idle trying to "bleed" the system the temp stayed about normal. I have "bleed" the cooling system more than once and I am having to keep adding coolant but I think that is because it keep comming through the purge tank cap. This car has about 166,000 miles on it and I don't know the maintenance history on it but I have had the car for about 4 years now.

Does this sound like a possible blown/leaking head gasket? Intake manifold gasket? How hard is it to do either one on this engine?

Thanks for the help in advance.
Jeremy

[GTP Dad]

Are you getting any water in the oil? How about smoke from the tail pipe that smells like antifreeze? If no know to either then check the waterpump and the air dam under the front of the car. Usually if the waterpump is good it will pump water faster at high speeds and cool the car down. Also when did you change the thermostat last although I don't think that is the issue.

If you suspect a head gasket do a compression check and see what the compression is per cylinder. A low reading on one or two cylinders, especially on the same side may indicate a bad head gasket. Water in the oil would indicate a bad intake manifold gasket.

[jbmx4life]

Water pump should be good as I just replaced it last summer (what a job). I changed the thermostat the winter before because I wasn't getting any heat in the passenger compartment (turned out to be heater core plugged). No antifreeze smelling smoke from the tailpipe. I haven't checked the oil yet but will do. Last time I checked the compression all was good (I think that I checked it last summer when I had another cooling issue). My other cooling issue from last summer turned out to be that the "fins" on the radiator were plugged. When I flushed water through them it was all black and dirty. Might that have happened again? I also went and bought a new cap for the purge tank today as it might not be getting the proper pressurization and that might cause it to overheat, right? Thanks for the help thus far.

[jbmx4life]

Well as I was posting the above ^^ last night I had the car running trying to "bleed" the cooling system once again. I let the car run for an hour before I put the cap back on and took it for a ride. Well here are my findings:

Car runs fine in the city (temp wise)
Car temp starts to climb rapidly on the highway
Car temp starts to cool once back in the city and the heat on full blast
I checked the oil and there is no indication of coolant in the oil (doesn't look white on the dipstick of the oil fill cap)

I have the car in the garage right now and after sitting over night, I am going to check the compression on it and prolly change out the thermostat (again). Any other ideas are welcome also.

[jbmx4life]

Well I changed out the thermostat again and I also removed the radiator to flush that all out again. When I put it back together I let the system bleed for an hour and then I took it for the highway test drive. Everything seemed normal as the temp hovered around the 1/4 mark on the gauge. The next day I had to make a 1 hour road trip and as soon as I hit the highway it went up to 220 again. I made it to my destination and then the car sat for a week as I was on vacation (I loved Florida). As I was making my way home on the highway I feared the worst but the temperature ran on the 1/4 mark all the way home . After I got off the highway I laid the throttle to the floor and then the temp started to climb again and didn't go back down. WTF is going on with this thing? I am almost certain that it seems to be a head gasket with a small leak to the cooling system but I would like to get some more opinions before I tear it apart for no reason. Thanks!

[GTP Dad]

Is the front air dam in place under the car? It does a lot of air direction when you are at highway speeds and without it the car can overheat. Personally I still think you have a problem with the water pump. Usually they respond just the opposite of what you describe but anything is possible.

[Slade901]

Could it be just a coolant temp sensor is gunked up that needs cleaning or just in need of replacement?

[snowtroll669]

if it was my car i think i would replace the water pump agine do you have pressure in the hoses and try driving on the highway with the cap off see if it does the same thing sqeezze the top rateator hose see if it is really easy to squeezze or is there some resistance in the hose sounds to me like your not getting your coolent fluid back to the rateator

[Slade901]

BTW, just make sure you did not put the thermostat upside down. Some vehicles you could put the t-stat in the wrong direction and still fit but then you will issues with the cooling system and overheating in some odd situation and once the t-stat is placed back in the right direction then it was fine.

[Northcat]

First thing I would do is I would take it to the car wash or if you have a pressure washer at home, I would clean the radiator out. Spraying it from engine compartment out the front of the car.

2nd, I would make sure the cooling fans are running. You say you can keep the temp stable by turning on the heater...this would seem that no matter how little air you are pulling through the heater core it is helping cool the engine.

3rd, the coolant resevior should remove air from the system on it's own, you could have a bad cap. $7.00 autozone.

4th, you could try the temp sensor, it's only $7.00

if none of those things are the problem, I've got dollars to donuts that says you have a cracked head. Cracked around one of the exhaust valves.

If a head gasket goes bad you'll either have coolant leaking down the side of the engine or you'll get some in the crankcase.

If the head is cracked around the exhaust valve, your compression will check out within specs.

If you are losing coolant, there are only 3 places for it to go, on the ground, in the crankcase or out the exhaust valve.

I had a similar problem just a couple of weeks ago, kept bleeding the system, car would run around 220 and on the highway temperature would rise occasionally.

Tore it down 3 times, replaced intake gaskets, put it back together, same problem, replaced head gaskets, put it back together, same problem. Replaced heads and head gaskets, put it back together, no more problem.

I found used heads at a junkyard for $75 (for the pair, usually $150 for the pair but I know him).

[jbmx4life]

Originally Posted by Northcat

First thing I would do is I would take it to the car wash or if you have a pressure washer at home, I would clean the radiator out. Spraying it from engine compartment out the front of the car.

2nd, I would make sure the cooling fans are running. You say you can keep the temp stable by turning on the heater...this would seem that no matter how little air you are pulling through the heater core it is helping cool the engine.

3rd, the coolant resevior should remove air from the system on it's own, you could have a bad cap. $7.00 autozone.

4th, you could try the temp sensor, it's only $7.00

if none of those things are the problem, I've got dollars to donuts that says you have a cracked head. Cracked around one of the exhaust valves.

If a head gasket goes bad you'll either have coolant leaking down the side of the engine or you'll get some in the crankcase.

If the head is cracked around the exhaust valve, your compression will check out within specs.

If you are losing coolant, there are only 3 places for it to go, on the ground, in the crankcase or out the exhaust valve.

I had a similar problem just a couple of weeks ago, kept bleeding the system, car would run around 220 and on the highway temperature would rise occasionally.

Tore it down 3 times, replaced intake gaskets, put it back together, same problem, replaced head gaskets, put it back together, same problem. Replaced heads and head gaskets, put it back together, no more problem.

I found used heads at a junkyard for $75 (for the pair, usually $150 for the pair but I know him).

I already have taken the radiator completely out and flush it thru the inside and thru the fins. (Previously stated)

The cooling fan works also and it pulls alot of air.

I thought it to be a bad cap before and I have already replaced but it didn't help. (Previously stated)

I doubt it to be the temp sensor due to the fact that it keeps spewing coolant from the cap everytime it gets to 220+.

I am guessing either a cracked head or a possible head gasket leak. There is no visible tell-tale signs of what is going on either. No milky oil on either the dipstick of the oil fill cap, no coolant on the ground (except for when it spews out the cap), and no constant white smoke or coolant smell out of the exhaust. If I do go ahead and do the head gaskets I would also have the head redone as the car has 166k on it and it would be senseless to just slap new gaskets in. I have yet to do the compression test (been busy) but the car doesn't get driven very far anymore so it is not too much of a worry for right now. Thanks for all of the responses and suggestions so far and keep em comming!

[skibum1111]

Hmmm.... Radiator is ok, pump is ok, thermostat is ok, hoses are good, car overheats on the highway. Check your knock sensor. It might be giving a false reading to the computer which will change the timing, slow the car a bit which won't be noticable if you don't drive it much, and will do funny things to the amount of heat you have. Other than that, pull the water pump off, look in the cooling jackets for anything in there. Same with the water outlet, should be able to look around in there as its a big hole. If there is crap in there, find a compteten shop to do a high pressure flush. The gm dealer here will do a chemical flush, takes about 4 hours and costs around $500, but it cleans all the crap out of the system. Do that as a last resort. You are not getting coolant in the exhaust or oil, so I seriously doubt a bad head or head gasket. Good luck.

[jbmx4life]

Well I still haven't gotten this problem fixed. I have still been searching for a solution. I am starting to think that the block might be "balled" up as skibum has said. I did change the heatercore on it awhile back and when I had the old one out I took it apart. Needless to say, the car was not very well taken care of as the heater core was plugged tight. I am wondering if this is possibly happening to the water jackets in the block or maybe inside of the other hoses? LMK what you guys think.