Granning RT500-F53 pump problem

[dodger34]

Good morning!
Ref:Granning RT500-F53 tag axle suspension.
I have a 1995 MA3757 MountainAire Gasser (sorry, I figured the problem may be universal for a DP as well)
I have lurked enough and have done a fair amount of searching of the forums about the problem I am having. The air suspension pump runs full time of late with the controls in "on" and "inflate" positions. (No gauge at the driver controls) On a side note, I found what appears to be a tire type valve stem on the back wall of the basement compartment near the air pump. Is that for reading pressures on the air tank?. I have done a very basic inspection (darn tight for an old man) and can not find an air leak. Has anyone had the same general problem and if so do you have any solutions? I am about two weeks from traveling and do not want to damage the unit. I live in a cold area so I am not discounting that it could be ice.
Thanks for any help,
dodger

[GaryKD]

Hi dodger34,
Welcome to iRV2. If the compressor is running all the time there must be a leak or the method of telling the compressor to stop is malfunctioning. Very cold weather can make unusual things happen. It may be that there is some cold weather binding of valves or switches. With the compressor running, I know I could not hear a leak. There could be a ride height valve stuck or worn and leaking.

The compressor must stop or it would inflate the bags a whole lot more than they should be inflated. Is the coach coming up to ride height? That would say the compressor is working (not just running).

If you are getting to ride height, for me, I'd wait until you get to warm weather. If the coach is not coming to ride height consider having a tech correct the problem before traveling.

[53panhead]

My Mountain Aire has two switches, one for inflate/deflate, one for power to the compressor. If you turn off the power switch, the compressor should stop running. There is a relay mounted at the compressor that is controlled by the power switch. If you turn off the power switch and the coach settles down, then you have an air leak somewhere.
The tire stem is the way to check air pressure.
Good Luck.

[dodger34]

Thank you for the responses.

GaryKD:Yes, I do get inflation of the bags and you are most likely right about not being able to hear air escaping. It is about 14 F. this AM so I will allow it to get a little warmer before I climb under.

53Panhead: My controls are as you identified. Also, the bags do settle after a while. I appreciate your identifying the tire stem as that will allow me to check if the compressor is over pressurizing or just not keeping up.

If anyone has had a like problem I would be interested in the specifics and the solutions.
Thanks again,
Dodger34

[dodger34]

Good afternoon,
Appears to be several areas of leakage at the spitter valve designed to remove moisture from the air tank. Has anyone replaced the valve? According to a parts list the part number should be #5442 Valve-Spitter (heated).
I believe there are three possible solutions, find a rebuild kit for the valve, buy a complete replacement, or remove the spitter valve and put a petcock in place of the valve. Any recommendations?
Thanks,
Dodger

[a k]

You sure it isn't a Meritor valve?

[dodger34]

AK,
I do not believe it is a meritor valve just from looking on line but the Meritor 704916-01 might be a suitable substitute if I have problems with the existing style. Thanks for the suggestion! I believe I will try a manual valve with a pull line and hope I can find a rebuild kit for the original unit.
Thanks again,
Dodger

[a k]

The air valve only purges only when the compresor cycles off. You should be able to get some sort of numbers off the water seperator valve. I think if you call Newmar they could tell you which one was used.

[dodger34]

It turns out the auto moisture removal valve is a Haldex Midland.
I purchased a manual spitter valve from an auto parts store about $8. I removed the old valve and installed the new one. The compressor pumped up and shut off! As of about 36 hours the tank is holding at about 50 lbs. I will try to buy a rebuild kit for the old valve, recondition it and reinstall. The manual valve has a lanyard so it can be operated from outside. Thanks to all for your help.
Dodger