940 heater cold

[Tony Stanley]

940 turbo estate, 95, UK, manual, non-air con

Recently my heater seems to be playing up. It was always a bit crap with it still not hot when the temp guage is right at the middle, but now its blatantly cold with the engine warm, moving the heater control up and down seems to allow it to warm up.

The cooling system was drained when I replaced the heater control valve during the summer and didn't seem silty, as usual I added anti-freeze.
There is plenty of water.

Is it common for these heaters to not flow very well or get air locks, or is just a one off blockage somewhere?

 

[Mike F]

940 turbo estate, 95, UK, manual, non-air con

Recently my heater seems to be playing up. It was always a bit crap with it still not hot when the temp guage is right at the middle, but now its blatantly cold with the engine warm, moving the heater control up and down seems to allow it to warm up.

The cooling system was drained when I replaced the heater control valve during the summer and didn't seem silty, as usual I added anti-freeze.
There is plenty of water.

Is it common for these heaters to not flow very well or get air locks, or is just a one off blockage somewhere?

Make sure that coolant is actually flowing through your new heater valve. When you have no heat, see if the heater hoses inside the car are hot to the touch. (I know, easier said than done.) Make sure vacuum is getting to the heater valve (no vacuum = closed valve), and that the visible lever is moving. Finally, there is a blend door that controls the amount of air that goes through the heater core - make sure it's moving to the right position.

 

[Peter Milnes]

Mike, surely on non air-con equipped cars the heater valve is cable operated and inside the firewall. Not nit picking, just have a 945 with ordinary heating and cable operated valve.

Cheers, Peter.

Tony Stanley wrote:

940 turbo estate, 95, UK, manual, non-air con

Recently my heater seems to be playing up. It was always a bit crap with it still not hot when the temp guage is right at the middle, but now its blatantly cold with the engine warm, moving the heater control up and down seems to allow it to warm up.

The cooling system was drained when I replaced the heater control valve during the summer and didn't seem silty, as usual I added anti-freeze. There is plenty of water.
...

 

[Mike F]

Mike, surely on non air-con equipped cars the heater valve is cable operated and inside the firewall. Not nit picking, just have a 945 with ordinary heating and cable operated valve.

Cheers, Peter.

Actually you may be right. Over here, all Volvos have had the more expensive heating system. Even in the few years that 740s came without A/C as standard, they still had that system, which made adding A/C at the dealer level possible. I just plain forgot that the rest of the world had a different system sometimes. I would imagine that system more or less works the same way (blend door and heater valve).

 

[Peter Milnes]

Sure does, but manually operated, the cable operates the door and the valve together. The valve is first then the rest of the cable goes up to the door.

Cheers, Peter.

Peter Milnes wrote:

Mike, surely on non air-con equipped cars the heater valve is cable operated

and
: > inside the firewall. Not nit picking, just have a 945 with ordinary heating and

cable operated valve.

Cheers, Peter.

Actually you may be right. Over here, all Volvos have had the more expensive heating system. Even in the few years that 740s came without A/C as standard, they still had that system, which made adding A/C at the dealer level possible. I just plain forgot that the rest of the world had a different system sometimes. I would imagine that system more or less works the same way (blend door and heater valve).
--
...

 

[Tony Stanley]

It is a manual cable, and I would expect the hoses are cold, I am reasonably sure the water isn't flowing through. I have monitored it more closely over the last few days and it is losing water. Possibly the water dropping is causing a short term airlock.

Anyway my question is now what might be leaking. It is losing about 1.5 litres over a 25m trip, but sometimes loses it overnight. Its strangley inconsistent and I can't identify the leak. The only thing I can see is a small damp patch ontop of the join from the exhaust manifold to the turbo after the engine has been sitting cold overnight. Are there any waterways in there?

I was worried initially that it was the head gasket, not helped by the overboost, but there is less evidence of that.

 

[James Sweet]

It is a manual cable, and I would expect the hoses are cold, I am reasonably sure the water isn't flowing through. I have monitored it more closely over the last few days and it is losing water. Possibly the water dropping is causing a short term airlock.

Manual cable?? All 700 series cars that I'm aware of use a vacuum operated heater valve, did they change this on the 900's?

 

[Grtdane]

It is a manual cable, and I would expect the hoses are cold, I am reasonably sure the water isn't flowing through. I have monitored it more closely over the last few days and it is losing water. Possibly the water dropping is causing a short term airlock.

Anyway my question is now what might be leaking. It is losing about 1.5 litres over a 25m trip, but sometimes loses it overnight. Its strangley inconsistent and I can't identify the leak. The only thing I can see is a small damp patch ontop of the join from the exhaust manifold to the turbo after the engine has been sitting cold overnight. Are there any waterways in there?

I was worried initially that it was the head gasket, not helped by the overboost, but there is less evidence of that.

Tony

Check the small hoses that feed coolant to the turbo. I had one that leaked straight down on the turbo, and it being really hot would evaporate the water instantly. I looked for this one for about a month, and found it by chance.

Harold

 

[Mike F]

Manual cable?? All 700 series cars that I'm aware of use a vacuum operated heater valve, did they change this on the 900's?

There was a different heating system we never saw in North America that did not have any place to install an evaporator, and so A/C was not possible in these cars.

 

[Mike F]

It is a manual cable, and I would expect the hoses are cold, I am reasonably sure the water isn't flowing through. I have monitored it more closely over the last few days and it is losing water. Possibly the water dropping is causing a short term airlock.

Anyway my question is now what might be leaking. It is losing about 1.5 litres over a 25m trip, but sometimes loses it overnight. Its strangley inconsistent and I can't identify the leak. The only thing I can see is a small damp patch ontop of the join from the exhaust manifold to the turbo after the engine has been sitting cold overnight. Are there any waterways in there?

I was worried initially that it was the head gasket, not helped by the overboost, but there is less evidence of that.

Generally when coolant disappears it's a problem with the head gasket. The heater seems to empty first when coolant levels drop.

 

[James Sweet]

There was a different heating system we never saw in North America that did not have any place to install an evaporator, and so A/C was not possible in these cars.

Ah, didn't notice the poster was elsewhere. That always seemed weird to me, that such stripped down models were available elsewhere than here. As far as I know, *all* 700 and 900 series cars in North America came from the factory with power steering, power windows, power locks, air conditioning and heated seats. Every one that I've ever seen had a sunroof as well, though I've heard rumors of a few without.

Were some/all of these options over the years in Europe? I'd be curious to see the statistics.

 

[Mike F]

Ah, didn't notice the poster was elsewhere. That always seemed weird to me, that such stripped down models were available elsewhere than here. As far as I know, *all* 700 and 900 series cars in North America came from the factory with power steering, power windows, power locks, air conditioning and heated seats. Every one that I've ever seen had a sunroof as well, though I've heard rumors of a few without.

Were some/all of these options over the years in Europe? I'd be curious to see the statistics.

In 1985 all 740s in Canada had manual sunroofs, manual mirrors and no A/C. In '86 A/C was added. A little later came the power mirrors and sunroof. In 1990 they started selling lower content plain 740s (no letters) that had A/C (and sunroof) optional again. All our 740s did have the vacuum heater system that could have A/C added. We did get some 240s in '77 and '78 that had a cheaper cable heater system that didn't have provision for A/C to be added though.

A friend of mine had a 1983 760 GLE without a sunroof, it must have been a special order, the owner wasn't the first and didn't know the history.

 

[Tony Stanley]

In 1985 all 740s in Canada had manual sunroofs, manual mirrors and no A/C. In '86 A/C was added. A little later came the power mirrors and sunroof. In 1990 they started selling lower content plain 740s (no letters) that had A/C (and sunroof) optional again. All our 740s did have the vacuum heater system that could have A/C added. We did get some 240s in '77 and '78 that had a cheaper cable heater system that didn't have provision for A/C to be added though.

A friend of mine had a 1983 760 GLE without a sunroof, it must have been a special order, the owner wasn't the first and didn't know the history.

I'm actually in N.Ireland which has even more miserable weather than England. Sunroofs are a pain on older cars I avoid them if possible, they either jam or leak. My 940s is very leaky, from the drain hoses being not tight enough to other leaks I can't identify. I consider it a bad feature. Air con is a bit of a waste here although more cars are appearing with it as a sales feature. Its nice for about 3 days a year but not essential, the rest of the time the system is slowly seizing up and alot of cars it just doesn't work as the owners havn't bother to fix it. I even suffered my (manual) heater valve that wouldn't turn off fully for a summer. Temperature varies from occassion below zero, but mostly 3-4C this time of year to about 25C max in the summer.

I certainly wouldn't call it stripped down, air con is the only difference, and mostly not justified in this country especially in older cars.

 

[Tony Stanley]

Generally when coolant disappears it's a problem with the head gasket. The heater seems to empty first when coolant levels drop.

Checking again in the daylight (not much at the moment), I definately saw it comming from the join between the turbo and the exhaust manifold. I'll have to check now if its dribbling down from somewhere but it did seem to come from inside. It is a water cooled turbo, Mitsubishi I think from the Haynes manual and the direction of the wastgate pressure hose connection

There doesn't seem to be a gasket, is this right, could it be dribbling down inside from the head?

If weather allows I may atempt my first turbo removal at the weekend. Any advice?

 

[Tony Stanley]

closely is

Checking again in the daylight (not much at the moment), I definately saw it comming from the join between the turbo and the exhaust manifold. I'll have to check now if its dribbling down from somewhere but it did seem to come from inside. It is a water cooled turbo, Mitsubishi I think from the Haynes manual and the direction of the wastgate pressure hose connection

There doesn't seem to be a gasket, is this right, could it be dribbling down inside from the head?

If weather allows I may atempt my first turbo removal at the weekend. Any advice?

No hands dirty this weekend, but a fill up with antfreeze seems to have stemmed the flow, I guess the increased thickness may help, but yet to see how it copes with the longer work journey.

 

[Mike F]

No hands dirty this weekend, but a fill up with antfreeze seems to have stemmed the flow, I guess the increased thickness may help, but yet to see how it copes with the longer work journey.

Water you see coming from between the turbo and exhaust manifold is generally combustion condensation and is fairly normal. As you suspect, there is no gasket in this joint.

If this was coolant dribbling down from the head, the head would have to have a serious crack (very unlikely) in it somewhere, there's no gasket or seal that could leak coolant anywhere near there.

Broken studs are almost a given around turbos. Heat each nut cherry red before any attempt at removal. At least on your later style turbo you can remove the turbo from the manifold without removing the manifold from the head first. Other than that, it's fairly straightforward.