• Hello Guest, welcome to the initial stages of our new platform!
    You can find some additional information about where we are in the process of migrating the board and setting up our new software here

    Thank you for being a part of our community!

Heater Control Valve

lummert

lummert

Active member
Joined
Jan 11, 2008
Location
Portland IN
I had previously mentioned that I had a couple episodes where that when I got on it the engine would sputter and a white cloud would appear behind my car. It turned out to be the heater control valve. Normal driving would not make it leak, but anything over 2500 RPM's and coolant would spray out of the side of the valve.

Today I went to the junkyard and found two valves, one on a 92 960 and one on a 91 740. The valve and all of the heater hoses on the 91 740 were new Volvo parts.

I removed the heater hoses and valve from the 91 740. I found it easier and quicker to remove the intake manifold to remove the hose that runs under the intake. I also removed the temp gauge sender and the temp sensor while it was convenient to get at them.

When I started replacing the valve on my 88 765 with B230FT the valve broke off in the heater hose that runs to the heater core. It snapped of with just the slightest movement of the valve and hoses. I now have the valve and the hose from the valve to the heater core replaced and I will replace the other heater hoses when the weather improves.
 
Yep, those plastic heater valves will decay internally and snap right off. Eventually it would have snapped while driving and leaked out all the coolant. Replacing the heater valve on a 700 series car is one of the 'must do' stage zero tasks. It becomes even more important when you remember that around 1990 Volvo started putting on the green coolant tank cap without changing the specs of the valve. They increased coolant pressure from 11psi to 22psi! Personally, if I drove one of those cars I'd use the black cap. There is plenty of coolant temp reserve and the system doesn't need all that extra stress from the higher pressure in my opinion.

You should see the exploded radiator hose from a friends car that improperly had the green cap on it. It is torn open half the length of the hose. This was on his 1989 740gl. Non turbo doesn't need that damn green cap.
 
dl242gt said:
Replacing the heater valve on a 700 series car is one of the 'must do' stage zero tasks.
Click to expand...

What brand heater valve should we be using? I plan to install a black lower pressure cap, a new 185F stat, and a new heater control valve. Noticed the gfs 740 had a puddle of green crap underneath it today after I let it idle for like 20 minutes:roll: temps were like 203-208F which is a hair too warm imo for a cool day. Also gonna get rid of that green crap and install Toyota super long life pink

Pretty sure I saw some wetness on the very bottom of the valve in this picture.
https://www.rockauto.com/en/catalog...425,heat+&+air+conditioning,heater+valve,6860
 
PromiseRing said:
What brand heater valve should we be using? I plan to install a black lower pressure cap, a new 185F stat, and a new heater control valve. Noticed the gfs 740 had a puddle of green crap underneath it today after I let it idle for like 20 minutes:roll: temps were like 203-208F which is a hair too warm imo for a cool day. Also gonna get rid of that green crap and install Toyota super long life pink

Pretty sure I saw some wetness on the very bottom of the valve in this picture.
https://www.rockauto.com/en/catalog...425,heat+&+air+conditioning,heater+valve,6860
Click to expand...

I always use a motocraft yg136,as stated above it should be part of a stage zero.its the first thing I do.
 
oldnfast said:
I always use a motocraft yg136,as stated above it should be part of a stage zero.its the first thing I do.
Click to expand...

I was trying my best to keep this car original, but if I can make it more reliable then I will. I also read about the GM Astro van part number 660-1357 (NAPA) as an ‘updated’ unit. I have no problem with how the current one performs minus the leak. So idk about a GM part.

I wish there was an all metal option for even more reliability.
 
Looks like the motorcraft one is going to be my best option. Very similar design to factory and apparently decent quality.

Can I get away with an aftermarket 75kpa cap or should I shell out $35 for OE (I was thinking stant brand).
 
Last edited:
Jack said:
and Im the idiot
Click to expand...
At least you admit it8====D
Mr. V said:
IPD's valve is more than half metal; better than the all plastic crap most parts stores seem to carry.
Click to expand...
So is the Motorcrap valve I believe.

Who knows, her car only leaked coolant when I let t sit there and idle. I wanted to watch the fan engage but it never really did. Temps were around 205 or so, pressure building caused the leak. When moving it doesn?t leak. It?ll at minimum be receiving an 11 lb cap. Idk why the Volvo decided on a 22 pound cap. Stupid.
 
PromiseRing said:
At least you admit it8====D

So is the Motorcrap valve I believe.

Who knows, her car only leaked coolant when I let t sit there and idle. I wanted to watch the fan engage but it never really did. Temps were around 205 or so, pressure building caused the leak. When moving it doesn’t leak. It’ll at minimum be receiving an 11 lb cap. Idk why the Volvo decided on a 22 pound cap. Stupid.
Click to expand...

IIRC the Motorcrap valve is identical to Volvo's. I'm running a black colored Saab pressure cap. The pressure rating falls between the ratings of the Volvo caps. Stant R-34 cap for 88-98 Saab 9000 is rated at 15 PSI (13-17 range).
 
Last edited:
PromiseRing said:
At least you admit it8====D

So is the Motorcrap valve I believe.

Who knows, her car only leaked coolant when I let t sit there and idle. I wanted to watch the fan engage but it never really did. Temps were around 205 or so, pressure building caused the leak. When moving it doesn?t leak. It?ll at minimum be receiving an 11 lb cap. Idk why the Volvo decided on a 22 pound cap. Stupid.
Click to expand...

Do the valve regardless,they fail frequently.unless of course your low on funds,amazon sells the yg 136 for like $22.
 
Got the yg136 in today as well as a 180F stat (had a 198:omg:) and seems to be functioning well. Quick question though, I never see the heater control valve actually move when I turn the temp selector from hot to cold and vice versa. Air gets hot and cold like it should, but the valve never actually moves as far as I can see. Is this normal?
 
You must log in or register to reply here.
Back
Top