I am going to replace the thermostat in my 1996 850. After flushing and putting in new coolant I will have to bleed the cooling system to remove air bubbles. How does one do this? The procedure for thermostat replacement from Bay 13 in Volvospeed doesn't mention anything about bleeding the cooling system. I don't see a bleeder screw or anything of that type around the engine. Thanks.

Why are you replacing the thermostat? Did you take it out and test it and find it defective? If you do replace it make sure you replace it with a thermostat that does have the little bleed hole in it and not a standard US type with no bleed hole. To bleed the system all you have to do is remove the radiator reservoir cap and refill the system. If you have the correct type thermostat in there the air will automatically flow to the top of the system and bleed to the reservoir. Leave the cap off for a few minutes to allow air to escape, then run the engine till it warms up enough to open the thermostat and you start getting warm coolant back in the reservoir. All the air should be out by then. The small bleed hole in the thermostat allows air to escape without running the engine. Leaving the cap off the reservoir just eliminates any pressure resistance making it easier for the trapped air to escape. Running the engine afterwards with the cap off just moves any trapped pockets of air out and through to the reservoir. Once the motor is warmed up and you see no more bubbles of air you can replace the reservoir cap. It should be a green cap, not the old grey one. Good luck......


Mike

Thanks for the reply. I'm replacing the thermostat as preventive maintenance. I'm a big believer in preventive maintenance. Why wait until this part finally goes bad? With my luck, it will fail in the dead of next winter and who wants to be in that situation? I bought a thermostat from my local Volvo dealer. I know about the little bleeder hole you are talking about. Bay 13 procedure says to make sure its facing forward when installing thermostat.

Did you find out how, We are having the same issue, I can not find out how to bleed it after wards and now BOTH run hot after cleaning the radiator. Eric the car man is great but did not say how to do a volvo, and seeing how these cars do NOT have a radiator cap....HOW is this done???

Both what? Are you doing two cars? If you've replaced the thermostat properly and are using the prescribed amount of anitfreeze, you probably either have a lot of crud somewhere in the coolant passages or the water pump is failing. How many miles on the car and when was the timing belt last changed?

EDIT: it's probably best to start a new thread rather than replying to an old one, and include details on the problem you are having and what you've done.

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'96 850T and '83 244 DL both at about 200K, '97 850T5; gone but not forgotten '81 245 and '64 Amazon

I flush the system.
Then refill half of the total coolant volume with straight coolant.
Make sure the heat is on full.
Then top it up the the "min." line with distilled water.
Run the engine with the cap off up to operating temp. according to the gauge.
Shut the engine off and let it sit for 15 minutes (you can grab a beer at this stage)
The thermostat will open while you're waiting and trapped air will come out.
Restart the car and fill to the max line.
Go for a ride.
Check the level.
Done.
Enjoy the rest of the beer.

Did you find out how, We are having the same issue, I can not find out how to bleed it after wards and now BOTH run hot after cleaning the radiator. Eric the car man is great but did not say how to do a volvo, and seeing how these cars do NOT have a radiator cap....HOW is this done???