Richard --
Now I know why you're under-inflated!
When I was in the leak chasing state-of-mind, I found that the pressure
manifold itself was leaking at a fitting. This is that large steel block
that holds the solenoids.
Also, one of my solenoids had a crack in the bottom where the inlet pipe had
been over tightened. I'd start there. Unless you've got a filter with a
small enough size to trap a water molecule, you may also still have a leak
in your check valve. Crap gets in the seat of the check valve and it leaks
back.
Its a pain, but pump up the tank and then open the line between the check
valve and the compressor. See if you have leak back. You could also have a
leak at the pressure switch itself. That is through the diaphragm of the
switch.
For the tank to go flat in 20 minutes, you've got a pretty good sized leak.
I guess slow is a personal thing, but 20 minutes is fast to me. You should
be going at least a couple of hours for a leak to be "slow."
I'm a set-level-to-auto kind of guy, and ours only runs a couple of times in
a morning or afternoon of interstate driving.
You should be able to find it with a stout mixture of Dawn detergent in a
cereal bowl and a foam paint brush. Put a dishcloth under the air system and
start daubing it on. I think you'll find a leak that size pretty quick.
Mark Grady
'77 K
North Webster, IN
> -----Original Message-----
> From: owner-gmcmotorhome
> [mailto
wner-gmcmotorhome]On Behalf Of Richard Guthart
> Sent: Wednesday, February 03, 1999 11:03 AM
> To: gmcmotorhome
> Subject: Re: GMC: Starting pressure at zero (was:Thomas versus Dana)
>
>
> Mark,
>
> When I started working on the air system, both the schrader valve and
> check valve were leaking so I replaced them.
>
> Still have minor leak(s) to track down. If I set switch to "hold" the
> tank bleeds down in 20 minutes or so.
>
> (To get the time measurements for my recent post, I deflated the tank
> using its schrader valve.)
>
> BTW, any tips on where to look for the slow leak if soap solution
> reveals no apparent leaks from all tubing fittings?
>
> Richard
Now I know why you're under-inflated!
When I was in the leak chasing state-of-mind, I found that the pressure
manifold itself was leaking at a fitting. This is that large steel block
that holds the solenoids.
Also, one of my solenoids had a crack in the bottom where the inlet pipe had
been over tightened. I'd start there. Unless you've got a filter with a
small enough size to trap a water molecule, you may also still have a leak
in your check valve. Crap gets in the seat of the check valve and it leaks
back.
Its a pain, but pump up the tank and then open the line between the check
valve and the compressor. See if you have leak back. You could also have a
leak at the pressure switch itself. That is through the diaphragm of the
switch.
For the tank to go flat in 20 minutes, you've got a pretty good sized leak.
I guess slow is a personal thing, but 20 minutes is fast to me. You should
be going at least a couple of hours for a leak to be "slow."
I'm a set-level-to-auto kind of guy, and ours only runs a couple of times in
a morning or afternoon of interstate driving.
You should be able to find it with a stout mixture of Dawn detergent in a
cereal bowl and a foam paint brush. Put a dishcloth under the air system and
start daubing it on. I think you'll find a leak that size pretty quick.
Mark Grady
'77 K
North Webster, IN
> -----Original Message-----
> From: owner-gmcmotorhome
> [mailto
wner-gmcmotorhome]On Behalf Of Richard Guthart> Sent: Wednesday, February 03, 1999 11:03 AM
> To: gmcmotorhome
> Subject: Re: GMC: Starting pressure at zero (was:Thomas versus Dana)
>
>
> Mark,
>
> When I started working on the air system, both the schrader valve and
> check valve were leaking so I replaced them.
>
> Still have minor leak(s) to track down. If I set switch to "hold" the
> tank bleeds down in 20 minutes or so.
>
> (To get the time measurements for my recent post, I deflated the tank
> using its schrader valve.)
>
> BTW, any tips on where to look for the slow leak if soap solution
> reveals no apparent leaks from all tubing fittings?
>
> Richard
