When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
In the course of replacing the negative battery cable on my 1985.5 944, I had to remove the short hose from the block to the heater control valve, so that I could get a socket on the cable bolt. Should the heater control valve be attached to something, or is it just supported by the coolant hoses and the vacuum line? Mine is unattached. Since I'm in there, should I remove it and check operation, or do they tend to be reliable? (I've never run the car, so have no idea if the valve is working or not.)
JJ, these units are suspended by the hoses and are a known failure point. When they fail they can leak coolant into the flywheel inspection hole (at the top of the bell housing just to the left of the speed and reference sensors) and destroy your clutch.
I have sealed the inspection hole with a piece of aluminum held on by RTV (removable) since I use the flywheel gap in the bottom of the bell housing to set TDC. I also replaced the Porsche unit (plastic) with a metal heater control unit for Audi’s. It’s held in the same place by hoses only, just slightly rerouted. Do a search on Rennlist for that if it interests you. In any case, I would replace that unit and definitely check those hoses to protect your clutch.
PS - I have a turbo and I’m assuming that your car is built very similarly. Good luck.
Excellent advice and input, thanks. I'm replacing the removed hose, of course, and will see about making a little cover plate for the inspection hole. I'll also remove the valve and check it's still operational under vacuum.
My flywheel is locked at TDC by the PO, and I think I can see the relevant mark through the inspection hole, if I'm not mistaken :-)
09-17-2019, 11:07 PM
Heater Control Valve mounting?
