‘97 850 Wagon Topic is solved

[BlackBart]

This may be a long shot (and already mentioned?) but on my '94 there is a switch / sensor / module above the fan on the backside of the radiator, that triggers the fan control. Ours failed and it overheated twice in short succession. Many years ago - that may have been one of my first searches of MVS fixes!

But as abscate said, fogging windows in the summer points to coolant getting out of the heater core or hose connections at the firewall. No pressurized cooling system -> way lower boiling point. I changed the heater core in my 850 long ago.

[850oldschool]

Do you have another cap you can try?

[andrewjllrar]

Well, thanks to Robert, I think I’ve found that my radiator fan isn’t kicking on. Looks like the connections are good. Anyone know how to test the relay? No fuses, right? Didn’t see one in the fuse box list.

[andrewjllrar]

New cap- new tank

Heater core replaced relatively short time ago

No more fogging

No smell of coolant inside the car- no wet carpet

No drips under the car- other than when the coolant spills.

[manovlov]

Weird thing is, temp gauge reads normal (which it did before the gasket blew), water pump was replaced not too long ago, thermostat was pretty new- but sat for two years (top hose heats up fine). I can’t remember if I heard the fan or not- but again no temp surge on the gauge.

Consider my intervention as a newbie one :
If i understand well, the cooling liquid is hot, but the gauge says everything is fine. Why the fan doesn't switch on, could it be an electric problem ? Maybe a silly question, but are you sure to have feed the coolant system as it should be ? Volvo says 7,2 liters for a 850. You said you get some liquid on the ground, 7,2 liters make a huge trace. Are you in that case ? You said the water pump has been replace, was it a OEM one or an after market ? I've learn here that to try to win some money with after market parts is the best way to loose money and especilly time (because to have to do the job twice, at least...).

[manovlov]

No drips under the car- other than when the coolant spills.

...the coolant spills. can you expand ?

[andrewjllrar]

Under the overflow tank when it overflows and falls to the ground around the passenger tire.

This also means I haven’t lost all 7.2 liters. Just have to keep topping it.

Yes, I don’t go cheapie on engine parts.

[andrewjllrar]

Black Bart wins the guesses with a bad radiator cooling fan relay. Jumped per Robert DIY's video instructions and it engaged both high and low speed.

Question now: no 850's currenty at the junkyard. Does a '98 V70 have the same relay?

[scot850]

According to the link from IPD the 850 and later cars are the same:

https://www.ipdusa.com/products/22967/A ... sUQAvD_BwE

You probably already know that the relay slides in under the cowel. Careful when removing it as it is easy to break it or the wires/clips when they have been on there a long time. A spray of silicon oil or WD40 around the connectors and then careful use of a pair of adjustable pliers can usually remove them without breakage!

Good Luck!

Neil.

[andrewjllrar]

Thanks Neil, but whatever was in that plastic housing had already just crumbled into rot. Could be what caused the initial blown head gasket in the first place. So, now some splicing and connecting I guess.