Quick fix for a leaky air regulator

[Dallas]

Caution: Not meant to be a permanent repair. For informational purposes ONLY. Use this method at your own risk. The Author assumes no responsibility for the actions of others at ANY time or for ANY reason

A while back I was moving my bus and noticed that the compressor was kicking in way too often, about every 5-7 minutes.
When I shut off the engine I could hear air leaking from inside the drivers tool compartment so after a few days I looked in there to try and figure out where the leak was coming from. I had hopes that the leak was just a broken fitting or possibly a line had vibrated loose, (Yeah, Right!).
It turned out to be the air pressure regulator that supplies air to the auxilliary air tank, which supplies air to the air horn, wipers and on my bus the long gone heating system.
Now, to begin with, I do carry a lot of extra parts, among which are a few pressure regulators, but I wanted to do this to show that you don't have to be stuck on the side of the road with a major air leak from some little diaphragm that decides to let go at the worst moment in the middle of Podunk Junction.

First, I spent the longest time removing the regulator. According to the book, the compression fittings were put together with aircraft permatex and hadn't been touched in 50 years or so. Good stuff that permatex, except when you want to take stuff apart. 1/16th turn at a time with an end wrench.

After getting the regulator out, I examined the thing and found that it had been leaking from the diaphragm. Now, these regulators are actually quite simple in consrtuction, just a spring, some retainers an adjusting bolt, and a diaphragm with a ball on one side and a spring seat on the other.
The ball and spring seat are bolted together with the diaphragm inbetween and are meant to be rebuilt.

I cleaned up all the parts with brakekleen and took a close look at the diaphragm itself. Someone, at sometime had had a leak and used a piece of leather to make a new one. Good idea in a pinch, but leather does crack over time and that's what this one had done.

I looked around and found one of those baking sheets they sell in stores that is made from silicone and has a lot of give to it. I also had some cork gasket material, about 1/32" thick.

You can see by the pictures I cut out a piece of the silicone sheet and 2 pieces of the cork to fit the old housing.

For sealer, since silicone WILL NOT stick to silicone, and RTV is a silicone sealer, I used PL polyurethane roof and flashing sealer. This stuff is the same as I use to seal windshield leaks. It's waterproof, dries flexible and stays that way for years. The big drawback is that if you get it on you, it will be there until it wears off.

I coated all the sealing surfaces with a thin layer of the polyurethane and bolted everything back together.

Back in the drivers tool box, I spent another happy 1/2 hour cavorting with the wasps and spiders that had taken up residence. Now the hard part was getting all of the fittings to thread back onto the regulator without cross threading.

Leave off the line that comes from the main tank and temporarily install a Tee with an air pressure gauge. Fire up the engine and build up pressure until the gauge you installed reads 65 psi. adjust the bolt on the regulator until air starts going through the regulator and filling the auxilliary tank. Shut the engine down, bleed off the air pressure and remove the gauge. Reinstall the fitting to the regulator, clean up your tools and other mess, wash your hands, close the compartment door, and Wah-Lah your off to the races, until you get to a place that has the right parts.

Mucher betterer than being stuck in a campground without a toad, trying to get parts from the pizza faced 18 year old at the local small town parts store or truck stop that don't know nuttin' about no buses!

[Dallas]

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[Sojourner]

Love your article about temporary emergency repair until getting proper part so it will last longer.

Well done...a salute to Dallas for his effort in his presentation.

This a "What & How to Do" article need to be add in MAK board data bank.

Sojourn for Christ, Jerry J

[oldmansax]

Now THAT'S Amazing!