Over heating 940 Turbo

You've pretty much answered your own question, but not put 2 and 2 together. Your symptoms are a classic stuck shut thermostat...

The radiator is still cold when the water is boiling yes?

Tim..

Thermostats fail. You can just remove it and see if the car runs too cold. Hopefully it does. Start the car with the reservoir cap off and see if the coolant shows signs of bubbling. That might indicate a condition where the exhaust is leaking into the coolant- that could be a leaking head gasket, cracked block or cracked head. it could also be trapped air.

When it gets warmed up. Stop the motor and run your hand over the radiator to feel for even heating of the core. That would show that it is not blocked.

Depending on how badly it overheated, it could have warped the head. A mechanic can do a leakdown test, or even use an exhaust gas analyzer to check for CO content at the reservoir.

If it was running well with no performance problems we can fairly-safely eliminate things like dragging brakes, timing problems, overly-lean fuel:air mix, etc.

If it boils coolant out then it is important to completely refill the motor. Air can get trapped in the block which can cause overheating. For the 240s I think the book says to run the motor until warmed up with the coolant reservoir cap off to allow the air to be purged, but there are special tools (pressure or vacuum fillers) to pull the air out I think.

It is also possible tha tthe water ump has a problem like the impeller separating from the shaft, but that would be a stretch I would think.

"AlexL" wrote:

__ __ Randy & \ \/ /alerie's \__/olvos '90 245 Estate - '93 965 Estate "Shelby" & "Kate"

does the heater work?..if not, the coolant is not in the block....be careful not to overheat the car too much...as, it is $1,000 or so to change a head gasket on a 940t...(i know :-( ... ) make sure to fix it while it is a "small problem"....my $.02......good luck !!....can you see any coolant leaking while idling in the driveway??

Hay thanks a bunch guys...

The radiator wasn't nearly as hot as I'd expect so there may be something to this thermostat thing. Was running the heater full blast trying to get a little bit further down the road, it works 100% - hairdryers aren't as hot!

I did pull the thermostat out to look at but it has some sort of rubber seal around the edge and think water would leak if I left the whole thing out.

Damn, thought for sure I reasoned out the thermostat...but will pick one up tomorrow morning and give it a try. Will let you know how it turned out.

Thanks again. Alex

$1000 to replace a head gasket?

Boy, am I glad I taught myself to work on cars.

Moral of the story: if you don't know how to work on cars, the repair costs of maintaining a Volvo Turbo car will most likely eat you alive.

Not for the feint of heart, or they without mechanical ability, but they're great when they are in tip-top form.

"Zen and the Art of Volvo Turbo Maintenance"

Remove the pressure cap (on the cold engine, of course!) and check it for cracks running parallel to the threads. It shouldn't vent except under extreme conditions, and cracks are common. The gurgling is normal with a warm engine after shutdown even if it isn't overheating, especially for the turbo models.

Mike

But if you do know how to work on them they're wonderful, very easy to work on, lots of space under the hood, easy to find parts.

i work on them a bit...but, i didn't feel good doing a head gasket swap...and, i needed it done asap, as it was my daily driver...i think it took my volvo guy, like 10 hrs or so start to finish, a lot of stuff had to come off the motor to do this......they can sure get hot.......

Well, replaced the thermostat and it works! The top of the thermostat had come apart - there wasn't any thing for the plunger to push against, so it could not open. Will flush the cooling system and change the oil soon, hopefully not too much damage was done.

Thanks for all the help...you will hear back from me I'm sure!

Thanks again.

thats good news AlexL.....just remember to take overheating very serious in these 940t's.....Or, have $1k saved up (or

11 hrs of labor and a good garage "set aside") in the event you get her real hot and blow the head gasket......Me, I was driving @ 80-90mph on open Wy highways and I was trying to "limp" after throwing off plums of white smoke (busted coolant hose) to the nearest farm house / phone....She just got too hot on me...but not so hot as to do much more damge...like melt the plastic electrical fittings and hoses/clamps (like my mechanic has seen)....

how do you like the 940t? it is a great mid 90's sedan, eh?

Yeah, fingers crossed - don't think I did too much damage. As for the car...I love everything about it except for the fact that all the plastic inside is broken/ratty and the leather seats are a mess. Mechanically I think it is a solid car. Maybe could use all new bushings, drive shaft supports (clunks when going between either forward or reverse), new shocks but other than that... Just cosmetic and I really don't care about that. I use it like a truck.

Thanks again everyone for the help. Alex

One final question to put this to rest went to flush out the cooling system... The manual says to open the "petcock" on the block to drain the coolant. For the life of me I could not find one...can anyone clue me in where to look on the 940 Turbo motor?

Thanks Alex

It might be a translation error and they just mean the typical threaded bolt?

Not sure about the 900's, but 240's and 740's have a petcock with a barbed fitting on it on the lower side of the engine block towards the back near the exhaust manifold. I normally just pull off the lower radiator hose over a bucket though.

That was my technique for yeas too, but on the occasions where I find the block drain it drains quite well.

Those prestone reverse flush kits work great too, but its been years now...

The petcock disappeared with the advent of the water cooled oil cooler on the 940 turbos. See that pipe that comes out of the block, then connects to a hose that joins on the "thing" at the base of the oil filter? That's where the petcock used to be. (The "thing" is the oil cooler.)

Ok then, no petcock...I did the lower radiator hose deal (man was that a bastard to get off and back on!) but upon refill, only got about 8 quarts of the 10 specified into the system... I suspect the other two were/are still in there somewhere. I'll continue to top off with strait coolant for a while to make up.

Thank you all. The car runs like a champ again! May just fire my mechanic! Alex

Run the car at idle up to temp with the coolant cap off (or at least loose) to allow air to escape from the system... that's what the manual says I think...

__ __ Randy & \ \/ /alerie's \__/olvos '90 245 Estate - '93 965 Estate "Shelby" & "Kate"