Volvo 850 T5 Thermostat Problem

[JosLozVolv]

Have a problem on my 850 T5 after replacing the thermostat (the old one was stuck open)

Changed it last night everything went okay had the car idling to remove air from the coolant system after topping it back up took it for a drive, no leaks great! There was alot of white smoke from the exhaust but this normally happens on start up (burns oil) so thought nothing of it.

Left for work this morning coolant light flashed on when taking a corner thought nothing of it got to work checked the level and it's below the min line

I have put cardboard on the floor to catch any leaks so i can hopefully find where they're from but there's nothing the coolant res is now empty after the car has cooled down

Hopefully this makes some sense I'm really just asking for some suggestions of what it may be? Where has all my coolant gone? Should I have installed a gasket between the housing?

[Luxobarge]

Every time I drain the coolant on mine the same thing happens, it seems to take one heat cycle to get rid of the air in the system, so just top it up and take it for another run and chances are it'll be fine.

If not, then indeed you have a leak (your plan with the cardboard is a good one) or it might be the heater matrix (check under the carpet around the tunnel) or the oil cooler in the radiator - check the radiator visually and check there's no oil in the coolant or coolant in the oil - same goes for the other end of the rad for gearbox cooler if it's an auto. DO NOT drive the car if there is evidence of coolant in either oil supply of course.

Probably just burping itself though.

[Bigfella666]

Joz

There is indeed ( or should be ) a gasket fitted to the thermostat housing

[DunkinBiskits]

theres no gasket on the housing, its an O ring fitted to the thermostat itself that seals the top to the bottom half.

[Rebuild]

Originally Posted by Luxobarge

Every time I drain the coolant on mine the same thing happens, it seems to take one heat cycle to get rid of the air in the system, so just top it up and take it for another run and chances are it'll be fine.

I've also noticed the same thing. Joz, top off the coolant and see what happens.

[JosLozVolv]

Thanks everyone!

I installed the thermostat o-ring so not a problem there

Topped up the coolant last night and this morning it was fine so must've just been a mix of spilling some when draining and air trapped in the system.

The drain plug stayed in the radiator by design meaning the stream coming out was similar to when you push your finger over the end of which probably meant I lost a lot more than I had expected.

I think what made me think it had lost coolant to a leak was that I had driven the car for about 20 minutes after letting the car idle with the cap off for a little to try to burp some of the air out of the system without the coolant light coming on and everything working fine. It was only after leaving it over night did the coolant light come on.

Anyways thanks for the help all is good now only a matter of time before I have to replace something else now