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I have started a new thread here, following on from the undetermined coolant leak, post-bleeding thread listed earlier.
Yesterday, I finally tracked down the coolant leak that has been occurring on and off with no regular pattern. It has been super frustrating. I posted earlier how the leak seem to be located near the center of the engine firewall. I had all coolant hoses and heater valve replaced weeks ago.
This morning after topping up 2.5 liters of water, I started the car and there was no leak. I let it idle for a good ten minutes and felt the hoses on either side of the heater valve. On both sides I could feel warm water/coolant. Is it common for a faulty heater valve to only leak at certain times?
I turned on the heater in the car and noticed that the pin did not move up on the heater valve. No hot air came out. So, clearly I think the problem is the heater valve and not the hoses connecting to it.
Is there a way simply to remove this heater valve completely; put a connecting pipe between the coolant hoses that fit into either side of the heater valve. Or, is it best to follow Kirby's advice and get one of the simple plastic heater valves such as Four Seasons 74803?
Charles,
If you remove the valve and just join the pipes, the problem you will have is that the cabin will not cool effectively on very hot days. On full cold, the tap closes, and this prevents the heater matrix in the cabin receiving any hot water. Thus the aircon works far better as it is not fighting a hot heat sink all the time. So i strongly counsel you to not do it. For the record, and I realise this is tempting fate, I have never had one fail - they mainly fail through rust which is caused by poor coolant maintenance. You have just had bad luck.
Actually, heater valve are pretty reliable, you have just had bad luck. If you bought it from someone reputable (eg David Manners, SNG etc) they will replace it no question.
I would stick with the OEM style, even if you have to buy another; fitting is easy, it all works as it should, etc etc. I wold check that at full cold (ie temp to lowest setting) there is vacuum to the pipe to the tap though.
had similar problem on my 94 xjs. Note that when no vacuum is applied the heater valve is open and coolant will flow through the heater matrix. a vacuum is applied to close the valve. in my case the valve itself was leaking so I replaced it. The membrane that closes the valve failed a few years later and the valve stuck open. Replaced again.
I would check a couple of things on your valve (1) attach a pipe to the valve and "suck" on it to see if the valve operates, if it does then you have a vacuum issue elsewhere. (2) there is a small pipe that goes from the valve to the cylinder head, the pipe clamp at the cylinder head end are difficult to get at. It may be that this is not tight enough
Thank you for the advice. Am I correct in assume that "open" for the heater valve is indicated by the brass pin on the front of the heater fully extended downward to the bottom position? That is the position of my valve regardless of whether I have the heater turned on or off in the car now.
Right after the heater valve was replaced, it would change positions when the heater was turned on. I believe it moved upward into the bulbous part of the heater valve.
When I captured it leaking water in the photo, it was in the fully extended downward (open) position.
As I first suggested when you mentioned your leak, I had a heater valve that only leaked when system was set to fully cold and the valve closed. At the time, original valves weren't available, but I sourced a good quality OEM one.
If your leak is similar, ie just happening when the setting is either fully open or full closed, I would just buy a good OEM valve and change it.
07-18-2021, 01:08 AM
Heater Valve
