Hi. Earlier today heater valve on my wife's '93 940 failed and most of the coolant was lost. We did not notice anything until we arrived at our destination about 4 miles away. Then we saw lots of steam from under the hood and when I looked under the hood it became obvious what happened. We let the car cool for several hours, then drove it home. Halfway home we stopped because the temperature gauge went to red. I walked home and brought some more coolant and my S70. Poured the coolant in and drove the other mile or so before getting home and shutting the engine off. I am ordering the new valve and heater hoses now, but am really afraid that some engine damage occurred. There was never any noise or other symptom from the engine at any time during this incident. I am really hoping no damage occurred as this car is our daily driver and kids hauler, etc.

Another question is can I use a valve that is more of a generic type? Rummaging in the various storage compartments of the car I found stored away by previous owner a box marked "Ready-Aire HEATER VALVE 5926 GDI MADE IN USA". I think maybe he wanted to carry a spare in case this catastrophe strikes. Unfortunately, I did not find this thing until after I drove the car home. I could have replaced the valve earlier. The question is does it matter if I use this valve to replace the one that broke? This one looks differently, as can be seen from this picture.

Dear Vladimir,

May this find you well. Absent a life-or-death emergency, I'd instantly park any car, that had lost its coolant (or oil). The reason: absent these fluids, the engine will quickly be heavily damaged or totally ruined. If I'm close to a destination, the tow charge will be less than a head job. If I'm far from a destination, I'm not likely to arrive, as the engine will fail.

I recall few posts dealing with oil loss. Rapid coolant loss seems mainly to result from radiator or heater valve failure. Plastic parts embrittle with heat and time. In colder climates, these parts will last longer. Steve's sage advice might be slightly qualified: in the US southwest, where triple-digit temperatures are common. a radiator's working life might be less than 10 years.

Hope this helps.

Yours faithfully,

Spook

Thanks for the advice. We did not notice the coolant loss until we arrived at our destination as there is no idiot light and the steam only became visible when we were pulling into our friends' driveway. They are less than 4 miles away from our house, so that would be the maximum distance we've driven after the valve failed. Hopefully there is no damage. I will install the new valve and see how things are.

That looks like the style I used to replace mine recently. I went with one made by four seasons. It is also used on many domestic vehicles.

The dealer one is quite costly and I would not trust the scantech aftermarket one. So I went with the newer style. Four Seasons used to make the in the OEM style but switched design at some point. It'll work fine.

As preventive maintenance I would plan on replacing it in about 8-10 years. If you have it that long..

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Paul NW Indiana '89 740 Turbo 140,000

Paul, thanks for the very useful reply. I also was looking on FCP site for replacement and they don't even offer the OEM part. Only an $18 third party one. Since I already have this on hand I am inclined to use it. The only puzzle is how to install it. It does not have the arrow, so which direction am I supposed to install it? How did you do it? Does it matter?

Thanks!

It is really important to change out the rubber and plastic items in your cooling system after about ten years: they fatigue and crack over time due to high underhood temperatures. Don't wait until failure.
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See the 700/900 FAQ at the drop-down menu above right.

http://www.summitracing.com/parts/PLR-5926/

i had to replace this valve 2 days ago in my daughter 93 940 because she had no heat. the vacuum failed and was closed shut.

all this valve does is allow hot coolant to enter/exit the heater core back to the engine. if you wanted to you could insert a plastic toothed pipe between the two rubber hoses and clamp it and have heat on all the time. you would then have to adjust matters by turning heat volume to max OFF.

the rub with this valve is it is S--T plastic which splits and can leave you like you discovered.

i would do a few things to ascertain your engine is still sound.

flush and refill your syst4em with fresh coolant. change your oil and filter
have a look at your plugs to determine color and see if any coolant has altered their color by reaching them. do a compression test

obtain this tool

http://www.tooltopia.com/index.asp?PageAction=VIEWPROD&ProdID=7117

or go to a garage and have them do it for you to find out if you have exhaust gases in your coolant. if you do not count yourself blessed.

you need to find out the status of your head gasket in the least invasive way possible.

Once I get the new valve on there I will start checking things. Is the leak detection tool you gave a link to really reliable? Sounds like it would be a godsend if it were.

Thanks!

Sorry, your picture didn't show when I first reponded. That doesn't look like the heater valves I've seen, but it could be the camera angle or there may be more than one type of valve (though I kind of doubt that.)

They look more like this:

Thanks for the picture. I know what the correct one is supposed to look like. I could see it in my car and on FCP site. The question is can I use the one I got? It is a generic type valve. Does not have the arrow, so I am not sure which way to install it. I need the car to be working ASAP, unfortunately, so I am willing to go with the wrong valve until the right one arrives or in case this one will work fine I am ok with running a generic. Any experience with these types of valve?

Thanks!

Hi Vladimir,

Sorry to hear about this...it's never fun when your car breaks down.

Are you screwed? It depends on what you mean by screwed. First the good news: you're probably not screwed in the "this engine is toast" sense. Catastrophic coolant loss on these cars usually doesn't completely cook the head or break too much, provided you don't drive it too much...though it sounds like you did drive it a bit, however. Hard to tell at this stage. (By the way, is it a turbo? SE? 16 valve? Or just a plain Jane normally aspirated 940?)

Now the bad news: you are very probably screwed in the "I need to block out a weekend and do a head gasket" sense. When these cars suffer a major overheating event like yours, that aluminum head warps and you'll need to pull it, get it machined flat again by a machine shop, and put it back on with a new head gasket. If you have all your ducks in a row, it is a solid weekend job. Most likely, though, it will stretch over two weekends--it would require part of the first to pull the head and get it to the machine shop. They'll usually need a few days at least to get the job done. Then you'd need part of second weekend to put it back on after you get it back from the shop.

Fortunately, there is an outstanding guide to the procedure in the 700/900 FAQ, and as engine repairs go it's genuinely not that hard to do. Not much required in terms of specialized tools, and a few tricks at key points (as outlined in the FAQ) can save you much heartache and frustration. I have done three of these and quite frankly it's nothing to fear even if you've never done one before.

That said, if you don't feel like tackling it you might want to give your general location in case someone on the board might recommend a good shop. If you're in the SF Bay Area I can help you out.

As far as the heater valve you found I'm not familiar with the model number off the top of my head so I can offer no guidance. If it is the right one, I'd take a really close look at it and make damn sure it's new before putting it into the car. If it's not, just get a new one and save yourself some trouble down the road. By the way, taking the head off makes changing the heater valve very easy. It's a true pain in the a$$ to change otherwise.

Good luck, and keep us posted on how it's going.

-Matt

94 940 NA
91 940 Turbo LeMons racer (RIP)
87 240 GL (RIP)

The car is a plain jane NA 8 valve 940 with Rex/Regina ignition. I am really bummed out to hear that I most likely warped the head. All in all I drove it no more than 8 miles total. Probably less. I also added coolant and saw the temp gauge arrow stay at normal for a while. Only spent very little time in the red zone, but still... I will put on the generic valve I have and see what happens. How do I check for head or head gasket damage? What if the damage is not severe and I drive the car with the damage? I am not sure I can have the car off duty right now. It is wife's car and she's busy. She can't drive my S70 because it is a manual transmission, so we are a bit stuck. If she can drive the 940with slight damage until I can get it fixed then it's probably ok. I am not looking forward to pulling the head, but what choice do I have? I am not in real good mood right now, but will put on the valve and add coolant and see what happens.

Thanks a lot for all the support!

I am in Western Massachusetts area and know of a few good shops. None of them cheap and I really can not afford big repair bills right now. Aaargh!

Once you get your heater valve sorted out and drive the thing you will have an idea of whether or not you'll have to do a head gasket job. Most common symptom that i know of is leaking coolant from between the head and block. It may not show up right away. In my case, I blew out my radiator and didn't drive it more than a half-mile. Fixed it and it never overheated again, but it took several months for the head gasket to wear through at the point of warpage and start puking coolant.

You may have dodged a bullet, though, and not heated it up enough to warp it, though I would be a bit surprised but very happy for you. Time will tell. Good luck.

Well, I got the valve on there and it seems to work fine. Heat turns on and off as it should. The car runs and sounds fine. I am truly hoping and praying for having dodged the bullet. The scenario was as follows. We left home when the car was fully cold (first trip of the day), then we drove less than four miles to the friends' house at which point we noticed much steam and no coolant left. I assume the coolant didn't start exiting until the thermostat opened at 92 degrees C. So that had to take some time. Then we let the car fully cool while at friends' place. Several hours. Then we drove about half way home until I saw the needle get into red zone. I parked it almost immediately and walked home and got some more coolant and my car. This took half an hour at least, maybe forty minutes. I put in what coolant I had, which was less than a gallon of 50/50 mix I keep at home and drove the rest of the way home. As far I as I know this is all the engine got for overheating. I am hoping we dodged it.

Thanks for all the support and help!

Once you get your heater valve sorted out and drive the thing you will have an idea of whether or not you'll have to do a head gasket job. Most common symptom that i know of is leaking coolant from between the head and block. It may not show up right away. In my case, I blew out my radiator and didn't drive it more than a half-mile. Fixed it and it never overheated again, but it took several months for the head gasket to wear through at the point of warpage and start puking coolant.

You may have dodged a bullet, though, and not heated it up enough to warp it, though I would be a bit surprised but very happy for you. Time will tell. Good luck.