stv valve leak- 66 vette

[Harry L.]

I just had my stv valve rebuilt because I discovered a leak at the bottom hole where the vacuum regulator is attached. I discovered it with my electronic leak detector. I do not use the vacuum regulator. So I sent another stv valve to be rebuilt.Got it back put it on and I still can detect a leak at that same hole. The rebuilder said it was leak tested to 300psi with Nitrogen. My question is there freon at the top of that diaphragm screen that the leak detector picks up or is there no way that I should pick up any freon there? I am getting ready to send another valve back to put another diaphragm in. With my first stv valve I lost 2lbs of freon in 3 years so the freon leak is small. Has anyone ever check that hole to detect any freon? Is it a big deal to replace the diaphragm or should it be left to the professional? Dutch

[Harry S.]

Re: stv valve leak- 66 vette

Harry, I'm not familiar with that problem. Why not rebuild the STV yourself. All you need is the diaphragm, R12 or R134 oil, some air pressure, some alcohol, some O-rings and about an hour. It's not difficult.

Good Luck.

[Harry L.]

Re: stv valve leak- 66 vette

Harry, what do you use the alcohol and the air pressure for? Thanks

[Harry S.]

Re: stv valve leak- 66 vette

I blow out any residual oil or contaminants then I use the alcohol to clean all the internal metal parts. When dry and clean I put it back together. Anywhere there is an O-ring I use R12 or R134 oil as a lubricant. I use R12 Freon so I use R12 oil.

[Larry M.]

[Harry L.]

Re: stv valve leak- 66 vette

Larry, my stv valve is not gutted, everything is intact, a garage just added the thermostatic switch to the firewall and is clamped to the compressor the evaporator tube. I also have the expansion tube clamped to the evaporator tube also. Dutch

[Larry M.]

Re: stv valve leak- 66 vette

Larry, my stv valve is not gutted, everything is intact, a garage just added the thermostatic switch to the firewall and is clamped to the compressor the evaporator tube. I also have the expansion tube clamped to the evaporator tube also. Dutch

[Harry L.]

Re: stv valve leak- 66 vette

The compressor is connected to the thermostat by a wired connection and then a line from the thermostat is clamped onto the evaporator tube. The expansion tube is also connected to the same evaporator tube. My stv valve is totally functional with all it's internal parts. Can you understand my setup. I know it is not correct, but it work good except for that small leak at the bottom of the stv valve.

[Harry L.]

Re: stv valve leak- 66 vette

Harry, after you rebuild your own stv valve, is there any way to test for leaks before you install it? Dutch