97 850 GLT turbo wagon overheating

whitewon9395 · Post by **whitewon9395** » 22 Mar 2010, 21:46

here it is, 97 GLT wagon with a turbo, new t-stat, water pump, radiator, new head gasket and still overheating!!!!! Just bought the car and don't know any other history. This is my first Volvo and don't know where else to look. If ya start it and let it idle it will run fine until it gets hot, I watched as the t-stat opened at 190 deg then the temp will drop a little then a few minutes later it will get so hot it boils over. I've tried it with the cap on and with the cap off and get very similiar results. I must add that I do not have the origional cap though if this matters It was missing when I got the car. I am planning on contacting my local dealer tomorrow for a replacement cap. Any suggestions as where to look next?

9394volvo850s · Post by **9394volvo850s** » 22 Mar 2010, 22:04

have you checked if the radiator fan comes on? does it overheat if the car is driving? I has a similar issue with both my 93 850 and 94 850 Turbo, fan wouldnt come on.

whitewon9395 · Post by **whitewon9395** » 22 Mar 2010, 22:13

yeah fan kicks on every time with no problem

Post by **polskamafia mjl** » 22 Mar 2010, 22:33

Have you replaced the ECT sensor? Usually the T-stat and the ECT die together and should be replace together.

Post by **jblackburn** » 22 Mar 2010, 23:06

True, but the ECT sensor wouldn't cause it to boil over...the thermostat is the sole controller of when the coolant begins to pass through the radiator and is cooled off. If the fan is still coming on when the car warms up, the sensor is working OK.

I know your head gasket was replaced, but I'm wondering if the head itself has been warped and causing exhaust gases to seep through once it starts to warm up. You can buy a cheap compression coolant system test kit at an auto parts store or online...I have seen the basic ones that change the color of the fluid for about $30 or so.

The cap shouldn't matter...I drove around with a cracked in half one for 2 months before I got a new one, and it didn't shoot anything out.

whoa · Post by **whoa** » 22 Mar 2010, 23:54

How hot does the return hose from the radiator get? That will tell you if you've got a circulation problem.

whitewon9395 · Post by **whitewon9395** » 23 Mar 2010, 03:38

which return line are you asking about?

Post by **charlyW** » 23 Mar 2010, 03:48

whoa wrote:How hot does the return hose from the radiator get? That will tell you if you've got a circulation problem.

Make sure that your radiator isnt blocked, if you're on about the large top hose it will get to a temperature where you cant hold it anymore, the smaller expansion line shouldnt get that hot at all as it doesnt do much mainly an vapour line. Get the expansion bottle cap changed it might have lost its seal so the vacuum isnt enough.

If it still boils over get a radiator cleaner solution and flush the system through because if you're replaced the pump/stat and the fan is turning on its almost impossible for the engine to boil over, idea try this unplug the coolant temp sensor on the thermostat housing the fan should be on consant see if the car then boils over if not its the coolant switch

whoa · Post by **whoa** » 23 Mar 2010, 08:07

The water goes into the top right of the radiator through the large hose from the thermostat that Charly is talking about. It leaves from a similarly large hose at the bottom left. If there is only a little flow in the system, the top (inlet) house can get very hot when the thermostat opens but the bottom (outlet) hose will not, because the radiator has a lot of time to cool the coolant passing through it. If there is normal flow but so much heat from the engine that the cooling system can't keep up, the outlet hose will be super hot too. Since OP has replaced everything else, if there is restricted flow, then there might be blocked passages in the engine. If not, there might be a coolant leak, bad expansion tank cap, slipping fan clutch. If that hose is weak, BTW, it can collapse and restrict flow (but I imagine the OP replaced the hoses, though he doesn't say).

Post by **jpgurley** » 23 Mar 2010, 08:32

I know that you replaced the water pump, however I did see an Auto Zone pump where the impeller came off the back of the shaft. It was a real challenge to find that one! I hope you didn't use a cheep pump.