Winesalot Posted January 12, 2017 Share Posted January 12, 2017 My 97 2.5L has been acting a bit peculiar lately. In the past the temperature gauge has for the most part been rock steady in the horizontal position right in the middle of the thermometer symbol. Lately it has been climbing about half way between the horizontal position and the high temp mark. After paying attention for a few days I noticed it does this in lower rpms and if I down shift it almost immediately drops back to it's normal position. Because the rpm increase helps bring the temp down I am inclined to believe either the thermostat is not opening all the way or the water pump is failing...either way raising rpm increases water flow and helps bring temps back down. My coolant levels are remaining constant and oil remains fine so I am inclined to believe it's not a head gasket problem dumping hot combustion gasses into the coolant. Any thoughts? Link to comment Share on other sites More sharing options...
Setnev Posted January 12, 2017 Share Posted January 12, 2017 Check that the thermostat is opening by touching the lower radiator hose. If its cold when the fans are on, the thermostat is stuck shut. Also check that your fans are coming on. If the fans come on and the thermostat is opening, make sure there is no blockage in the radiator. Use a heat sensing thermometer to check the different areas to make sure the temperature is uniform. The temperature fluctuation is a good indication of a failing head gasket, but the only way to test it is with a block tester. Autozone rents them and sells the fluid and the test takes about 10-15 minutes. A cheap and easy way to start to suspect a head gasket issue is to remove your radiator cap with the engine cool and radiator full of coolant and start the car. If it shoots out like a geyser, something is pushing the coolant out of the journals (i.e cylinder compression) Link to comment Share on other sites More sharing options...
doublechaz Posted January 13, 2017 Share Posted January 13, 2017 That sequence of rpms and temps is pretty much exactly what mine is doing. And all your other items match mine as well. I'm going with stuck shut after market tstat, but I won't be taking it apart until my funnel shows up. I'll boil the old tstat in a pan once I have it out to verify the failure, but I'm pretty confident. Link to comment Share on other sites More sharing options...
Winesalot Posted January 13, 2017 Author Share Posted January 13, 2017 That sequence of rpms and temps is pretty much exactly what mine is doing. And all your other items match mine as well. I'm going with stuck shut after market tstat, but I won't be taking it apart until my funnel shows up. I'll boil the old tstat in a pan once I have it out to verify the failure, but I'm pretty confident. I just made a five hour drive today including crossing a significant mountain pass. When the transmission was in third and I was aggressively climbing the steep part of the pass the temperature was rock solid but any time I was at lower RPMs in fourth gear temps climbed. I am not buying the head gasket diagnosis mainly becauce if combustion gasses were causing the temperature rise it would occur more significantly when rpms and load where the highest. Also, the coolant level has remained constant through this whole process. I also am discounting the fans as a problem. I am driving at highway speeds in below freezing temperatures. Unless the radiator is fouled my heat sink is doing its job. This is either an excessive heat problem (which doesn't make sense) or a lack of coolant flow problem. I am convinced either the timing belt is slipping on the water pump (because of the bad oil leak from the crank/cam seals or the water pump is failing internally, or the thermostats is not opening fully. This weekend the timing belt is coming off for they came/crank seal repair so I bought a water pump and thermostat to put on at the same time. I'll report back when I am done. Link to comment Share on other sites More sharing options...
doublechaz Posted January 13, 2017 Share Posted January 13, 2017 The pump is really simple inside. Direct drive, heavy metal impeller blades. Hard to imagine it failing to pump if it's turning. I think that timing belt would burn up and break pretty quick if it was slipping on the pump pully for very long. But with the direct drive in the pump, when rpm goes up the pump pressure and flow go up as well, as you would want since rpm usually means power which means heat. But that pressure could maybe push open a failed shut tstat. Anyway, that's how I see it until I find evidence otherwise. (And I also thought failing fans at first until I verified that they were working.) We'll race to see who gets theirs torn down first. Link to comment Share on other sites More sharing options...
Winesalot Posted January 13, 2017 Author Share Posted January 13, 2017 Race? Now you did it. Bring it on beeootch!!!!! Lol Link to comment Share on other sites More sharing options...
Winesalot Posted January 13, 2017 Author Share Posted January 13, 2017 I agree with your thoughts on the water pump but since I'm pulling the timing belt to do the seals I figured it's easy enough to replace it. Link to comment Share on other sites More sharing options...
doublechaz Posted January 14, 2017 Share Posted January 14, 2017 Oh, sure. In that far do the pump. Otherwise, how old is the seal around the shaft and how long before it goes? I did my water pump and oil pump the last timing belt change, but that was quite some time ago. Link to comment Share on other sites More sharing options...
Winesalot Posted January 14, 2017 Author Share Posted January 14, 2017 Amongst the other oil leak projects I am working on I did pull the thermostat and boiled it along side a new one. The old one never opened so I thing I have a verdict on that problem. I also found no signs of oil leaking around the cam or crank seals so I decided to leave the timing belt and water pump in place. I think all of my front end oil is coming from the power steering pump. Link to comment Share on other sites More sharing options...
doublechaz Posted January 14, 2017 Share Posted January 14, 2017 I hear that is a common leak point and that it makes such a mess that various front end seals are suspected. That sure will save you a bunch of work doing the timing and such later. Link to comment Share on other sites More sharing options...
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