mattd Posted January 13, 2005 Report Share Posted January 13, 2005 I really would like to know if a bad thermostat could cause your coolant temp to go up but not quite overheat. My problem is that when the car is fully warmed up and has been driven for a good amount of time and then is exposed to something like hard acceleration or going up a mountain access, the temp goes up. Usually it hovers around 96 to 98 degrees celcius. When I go up the mountain it goes up to around 105 to 110 degrees and I guess it pressurerizes the system and the surge tank cap starts leaking coolant. The car never really overheats. Could a thermostat cause this. I have no other leaks other then losing coolant through the cap. I have already replaced a cap with a new one rated at 15 psi. My second question is if I can replace the thermostat without accutally removing the lower rad hose. In other words, can I simply take those two bolts out and pop out the housing and change it that way? Or will this cause a problem that I sipmply don't know about. My car is a 97 Olds Aurora with 120K miles on it. Once again thanks for any input Link to comment Share on other sites More sharing options...
maydog Posted January 13, 2005 Report Share Posted January 13, 2005 That does not sound all that strange, what is the elevation of the mountain? The engine will have to work pretty hard to climb and the cooling efficency of the radiator will decrease with decreasing air pressure. Does the temp cool off once the ascent is finished? Link to comment Share on other sites More sharing options...
Oldgamer Posted January 13, 2005 Report Share Posted January 13, 2005 Sounds absolutely normal. And don't keep coolant level too high, otherwize you will loose "extra" coolant every time until it's level will be fine. Link to comment Share on other sites More sharing options...
JasonA Posted January 13, 2005 Report Share Posted January 13, 2005 My second question is if I can replace the thermostat without accutally removing the lower rad hose. In other words, can I simply take those two bolts out and pop out the housing and change it that way? Or will this cause a problem that I sipmply don't know about. If you do change your thermostat, yes, just remove the two bolts that bolt the lower radiator hose neck to the water pump cover/thermostat housing. No need to undo the clamp and slide the hose off. Just leave the hose connected and remove the two bolts. Jason(2001 STS, White Diamond) "When you turn your car on...does it return the favor?" Link to comment Share on other sites More sharing options...
Oldgamer Posted January 13, 2005 Report Share Posted January 13, 2005 You didn't get any of "Engine is overheated" or "Stop engine". Why bother to change thermostat if everything works fine? Don't waste your money and time. I remember the time after I bought a car and was concern about coolant temperature. Then I learn that this temperature is normal. And after all, remember the rule: if it works, don't mess with it. You can do more bad to the car than good. Link to comment Share on other sites More sharing options...
adallak Posted January 13, 2005 Report Share Posted January 13, 2005 If the coolant gets out because of thermal expansion not getting the boiling point under pressure it maight be caused by overfill, as oldgamer mentioned. But if you get boiling point I would check the coolant concentration (50/50), fans kicking off in time, water pump belt and tensioner and yes the thermostat might be the culprit as well. The saddest thing in life is wasted talent Link to comment Share on other sites More sharing options...
maydog Posted January 13, 2005 Report Share Posted January 13, 2005 I think if the thermostat was stuck, you would overheat. In addition to external conditions - the radiator may be partiall clogged. There is some discussion of this on the board. Link to comment Share on other sites More sharing options...
Oldgamer Posted January 13, 2005 Report Share Posted January 13, 2005 ... The car never really overheats... The car never overheats. You said it. Never got overheat related messages or something like that. So, my advice just do not overfill and do not worry. Of course, to check belt tensioner as adallak advised can't be bad either. But do it yourself, don't take car to the dealler. They certainly WILL FIND something wrong that "requires immidiate attention". Link to comment Share on other sites More sharing options...
mattd Posted January 14, 2005 Author Report Share Posted January 14, 2005 Thanks alot for all of your help. I just finished replacing the thermostat, took it out on a drive and was out for about 30 to 40 min. The car drove great and kept really cool at all times. It was at about 93 to 94 degrees the entire time. However when I headed home I had to go up the dreaded hill that seems to now go on forever. The temp jumped from about 94 to about 110 or so. When I pulled into my driveway I saw the steam again under the hood...once I pooped it I saw coolant all over the surge tank again... I am so depressed right now...the coolant was mixed 50/50 but only by eye. I had to 4L jugs and simply made sure both are even and topped up with water. Hope that OK...the level is definitely OK as well, made sure that I checked it a few times. I guess that it only leaves the head gasket...ahh I feel like someone just punched me in the stomach...I just spent over 2 grand on all this other stuff and now this. I will try letting the car run without the cap tommorow in my last attempt, thinking maybe there is some air trapped in the system, or something. Then I guess I'll take it to another mechanic to see if he can maybe put some more light on this issue. The car was pressure tested and didn't reveal any leaks and there are no traces of coolant in the oil. Would a mechanic know how to do this test that you guys talk about. The one with the spark plug and compressed air? Once again thanks for all your help. Link to comment Share on other sites More sharing options...
JasonA Posted January 14, 2005 Report Share Posted January 14, 2005 When I pulled into my driveway I saw the steam again under the hood...once I pooped it I saw coolant all over the surge tank again... What do you mean, you "saw coolant all over the surge tank"? On the outside of it? There SHOULD be no way for the coolant to get on the outer surface of the surge tank...unless the radiator cap is bad, no? Even if it does overheat, I would expect the outflow to exit through the vent tube (the one that leaves the cap area and is routed down towards the ground). I'd be suspicious of the cap if I saw coolant on the exterior surface of the surge tank. Jason(2001 STS, White Diamond) "When you turn your car on...does it return the favor?" Link to comment Share on other sites More sharing options...
bigboy6998 Posted January 14, 2005 Report Share Posted January 14, 2005 i had a very similar problem with my 97 eldo... The nipple that came out of the surge tank that went to the throttle body. This nipple cracked at the surge tank and started leaking all down the side of it and a little on the battery. I bought some new hose and was able to put the hose on the side of the nipple that broke off and put the recieving end into the tank with lots of epoxy glue. been like that for 2 years now and no leaks (i check it every time the hood is up) the glue is starting to look a little old so i may have to do something about it next summer. By the way i livein east texas so the last 2 summers it has been subject to some serious conditions. Link to comment Share on other sites More sharing options...
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