My 2008 XC90 3.2L (non turbo) is overheating badly. Please help diagnose it.

A week and a half ago I had a low coolant message and had my mechanic top it off. This weekend the coolant alert came on again and I topped off and drove at normal temperature until Monday morning on my way to work after 20min of driving I began to severly overheat and stopped driving.

I brought it into Swedish Motors yesterday to diagnose and they replaced the cooling fan and thermostat and the problem was not fixed and said I may need to replace the head gasket. The typical symptoms of a blown head gasket don't appear, full compression in cylinders, no coolant in oil, no coolant in exhaust, no oil in coolant)

The mechanic now wants to replace the water pump, but I feel like that is more of a fishing expedition. I didn't authorize the first two repairs and evidently they weren't the cause of the problem. I'm worried about being billed another $500 to treat what is not the cause of the problem.

Does anyone have any experience on XC90 overheating issues that may be relevant or have suggestions on what a next course of action should be?

1. Option 1 have the current mechanic replace the water pump $450
2. Option 2 have the Dealer do diagnostic testing $150-$200
3. Option 3 bring the car to another Indy mechanic for a $90 test on head gasket.

Thanks!

 

I would do no. 3.

 

They just guessed the fan and thermostat and charged you without your authorization? That is illegal, you know.

 

Thanks for your input.

I was very dissapointed he decided to change the fan (or do any work) without checking with me first. The mechanic offered to replace my original fan, which I'm leaning towards, but I'm back to square one without being any closer to diagnosing the problem.

Do you have any thoughts on what the root of the problem could be?

From speaking with 2 Volvo dealer mechanics by phone they are doubtful that it is a head gasket, but I don't have another theory.

 

Faulty coolant temperature sensor ??
How could they have diagnosed properly without doing the head gasket test previously?

 

How many miles in the car?

You have a coolant leak somewhere that is not properly diagnosed.
Pressure-test the cooling system to see where coolant goes.

Could be radiator...

 

I'm a dealer tech, too, and also doubt it is the head gasket. Can't say I've seen one blow on those SI6 motors.

I have replaced several water pumps on those motors, even under warranty. That could be the source of the leak.

I would get it out of that shop ASAP. And have them give you your money back since they installed parts without your authorization.

 

My thoughts as well. If you've had to add coolant, it went somewhere! I'd bet a bunch of money that it's related to the overheating.

 

I know I've gone through a bunch of coolant and it is not in the engine or out the tailpipe, where else could it go?

117,000+ Mileage, I bought the car used 18 months ago (one previous owner), put ~20kmi on it

Thanks for all your insight, I lurked when I purchased and first posted now, very much appreciate the help.

I'm in Boston and took the car to Swedish Motors in Allston, MA.

Let me know if you could describe the "pressure test to the cooling system" or if I can tell if there is a problem with the water pump without doing 3+ hours of labor.

I'm going to try to negotiate a lower payment for the mechanics time and effort for his work, he wants $800-900, what would you you offer if I ask him to replace the old fan?

Thanks

 

I've seen and replace plenty of water pumps on the new I6 engines. Is a good possibility that that could be the source of the problem

 

What do you mean replace the old fan? I thought they already replaced it? I would offer them nothing since they did the work without authorization, which is illegal.

A simple visual inspection of the water pump should be enough to see if it is leaking.

 

my over heating problem was related to my throttle body it kept overheating and going into limp mode , also other sources of overheating are your injectors are bad or too high rating and are putting too much fuel into the chamber

 

I'm encountering the same issue, verbatim. What was the resolution for you?