97 850 GLT turbo wagon overheating

whitewon9395 · Post by **whitewon9395** » 31 Mar 2010, 19:09

here is where we are now, The "new" water pump that I mentioned in the first post is the only item that I didn't physically replace myself (I was told by the previous owner that it was replaced) so to avoid any more doubt I replaced it yesterday and the one that was on it was still the factory pump (go figure), long story short it still boils over. I even bypassed the fan relay and jumped it to full time on in the higher of the 2 speeds and that didn't help. I have used a garden hose and I can shoot water into the tank and I can see it circulating thru the whole system (took the top radiator hose off of the t-stat neck). It will overheat if it's sitting still idling or if your driving, we are not losing any water (internal or external) unless you release the pressure of the cap after it overheats then it boils out. PLEASE HELP I have never had anything mechanical baffle me this bad!!!!

whitewon9395 · Post by **whitewon9395** » 31 Mar 2010, 19:20

another thought, even with the new water pump the flow seems to be very little, But I know the t-stat is opening. Is it possible for the opening in the block where the water pump sits to get worn out and make the "cavity" to large to pump sufficient water or not build up "pressure" so to speak?

whoa · Post by **whoa** » 31 Mar 2010, 19:55

I don't think your problem is passages that are too big, but if anything too small. There could be an obstruction somewhere. You might try back-flushing--putting water through the other way at high hose pressure--to see if anything frees up.

Thinking of mild-problem possibilities: Does the lower radiator hose get hot? (Sorry to ask again, but it matters; since you're saying low flow, I'm guessing it does not get hot.) Does it look kinked or collapsed while the car is running and hot (i.e., while there should be flow)? That would restrict flow.

Do you have coolant in the system, or just water at this point? In a normally-functioning engine, running just water can behave like you say your system is behaving (boiling in the engine, boiling over when the cap comes off).

If those easy things are in order, and if no one has a better idea, then what I myself would do would be to run water from your hose simply through the engine; from the water pump opening to the thermostat opening, take a video of it, do the same for just the radiator, post the videos and ask these Volvo old hands (or your cooling system repair shop guy, or maybe you would know yourself that it was or wasn't enough) if that is a reasonable amount of flow. Then you'll know if it's a bad radiator or an obstruction in the engine.

I battled a similar problem on an '77 Ford, determined with the hose method that there was an obstruction in one side of a V8 engine, and ultimately determined that a mechanic had installed the head gasket UPSIDE-DOWN! Fortunately for you, that particular mistake can't be made on the Volvo engine.

whitewon9395 · Post by **whitewon9395** » 31 Mar 2010, 20:06

Right now it is just water, as far as the temp of the bottom hose I'll have to check it tomorrow. I don't recall it getting hot or kinking but I'll double check it. As far as your comment about the upside down Ford head gasket.......I made that mistake myself many moons ago!!!!!

whoa · Post by **whoa** » 31 Mar 2010, 20:33

It's just water---but you have tested it in its current state with the right mix of coolant?

whitewon9395 · Post by **whitewon9395** » 01 Apr 2010, 04:49

no, I haven't. I'll try it today. Here is another odd part that I forgot to mention---After I bypassed the heater core (trying to eliminate all possibilities) we let it idle in my garage for about 45 minutes and it didn't overheat, took it on a test drive thru town and on the hwy and it still didn't overheat. We drove it for several days and it did not overheat, then low and behold it just started overheating again two days ago and nothing seems to help.

whoa · Post by **whoa** » 01 Apr 2010, 08:19

I'm thinking about bleeding air from the system; that used to be a big problem with Jeep Cherokees... So I just looked in the Haynes manual, and indeed there is a lot about that in section 1-31 (page 1-22) on "Coolant Filling". They say to fill very slowly, squeezing hoses as you go, until you reach the "Max" line; then warm the engine to normal temperature at idle, adding coolant if it goes under the max line (while the car is running---don't let the system suck air into itself); then let the car cool down completely (overnight), and top off in the morning to "Max". They then say:

"If, after draining and refilling the system, symptoms of overheating are found which did not occur previously, the the fault is almost certainly due to trapped air at some point in the system, causing an air-lock and restricting the flow of coolant; usually, the air is trapped because the system was refilled too quickly. In some cases, air-locks can be released by tapping or sqeezing the various hoses. If the problem persists, stop the engine and allow it to cool down completely, before unscrewing the expansion tank filler cap or disconnecting hoses to bleed out the trapped air."

A cut and paste from another topic about the 850:

When you refilled the system did you ensure that all of the air was expelled?

The heater control should have been on Max heat, the coolant added very slowly and the radiator hoses should have been massaged from time to time to get rid of air.

whitewon9395 · Post by **whitewon9395** » 10 Apr 2010, 18:41

Ok, today I took the thermostat back out and flushed water thru the system again, no apparrent blockages. I tried filling the whole system again to avoid air bubbles, and we installed a new cap on the expansion bottle. Now it doesn't overheat idling at all, it can sit and run for two hours and not come above the normal operating temp.But as soon as you drive it for 5-10 minutes at about 40mph it pegs the temp gauge and steam boils from under the hood. I hooked my timing light to it and it reads ridicuosly advanced, at warm idle about 90 deg advanced!!!! Is this possible? I am not used to the computer controlled timing systems that you can't adjust but I'm positive that an "old" style system wouldn't run like this. What in the world is going on????

whoa · Post by **whoa** » 10 Apr 2010, 18:53

90 degrees advanced---how exactly are you measuring that?

whitewon9395 · Post by **whitewon9395** » 10 Apr 2010, 19:39

with my timing light, I have a digital timing light that allows you to keep adjusting the light flash to coincide with the timing marks. I set it to 0 and the mark on the front cam is way out of alignment with the marks on the cover. And now that I'm thinking about it, it's reading that it is 90 deg retarded due to the fact that I had to set my light 90 deg advanced for the marks to align with the TDC mark on the housing.

97 850 GLT turbo wagon overheating

Re: 97 850 GLT turbo wagon overheating