Name that Doohickey

[flloyd]

Well, now I have an oil leak. It looks like hydraulic oil and is seeping out of the starboard side under the battery compartment. I have located a pressure regulator that is high, above the batteries, and behind the power steering reservoir that is covered in pink oil. What is it? It looks like an air pressure regulator. I doubt if oil flows through it, yet its covered. The fluid level in the steering reservoir is normal, however, judging by the mess under the bus, it looks like perhaps a quart or so of oil has seeped out, creating a nice mess (and showering the toad).

Transmission isn't leaking, levels are OK. It's a mystery.

[Pete]

Fred it is Prevost P/N 640938, Regulator, Belt Tension Air. available from Prevost for about $58.22 plus tax. Been there, done that!
If you have the feature that lifts the tag when you turn the steering wheel sharply in either direction. On my coach, it can be deactivated by a switch on the transmission console. (which I keep turned off). It is easily replaced, and I forget what the pressure should be set to, but the guys at Prevost can tell you. It is also used for other applications on the coach, but I would bet that is your issue. Hope this helps.

[flloyd]

Fred it is Prevost P/N 640938, Regulator, Belt Tension Air. available from Prevost for about $58.22 plus tax. Been there, done that!
If you have the feature that lifts the tag when you turn the steering wheel sharply in either direction. On my coach, it can be deactivated by a switch on the transmission console. (which I keep turned off). It is easily replaced, and I forget what the pressure should be set to, but the guys at Prevost can tell you. It is also used for other applications on the coach, but I would bet that is your issue. Hope this helps.

Thanks Pete,

I thought it was an air regulator. Probably not the source of the Hyd Oil, however. Not having any problems with the belts, that I know of.
The auto-lift feature was disconnected years ago and now hangs as a taped loose wire in the fwd electronics bay.

I guess that I need to look closer for oil sources. The location is almost impossible to reach and/or see. I've got an inspection camera that is sort of good. I'll keep looking.

-fred

[truk4u]

Pete & Fred,

The regulator for the belts/bellows should be high just inside the engine access doors just to the left of the Oil reservoir tank and should have a standard air/shrader valve and set to 50 psi.

[Jon Wehrenberg]

It is hard to say for sure, but it sounds like this is the pressure regulator that is near the house batteries in Fred's coach. I do not know its function, but it is located where a second auxiliary air system connection is provided for converters by Prevost on that vintage coach.

[Pete]

Fred, as I mentioned, the regulator is used for other applications as well. I am NOT talking about the regulator that controls the belt tension. If I am wrong, I owe you a steak dinner. Even though the electrical power is disconnected, air is still applied to the regulator, and if the diaphragm in the regulator is compromised, fluid will escape to the atmosphere causing a leak. Check the vent hole in the top section of the regulator to see if fluid is coming out. You may need a mirror to see the hole.

[dreamchasers]

Fred,

The picture you posted bring back recent memories. My coach suffered from the same symptoms, being an oil leak on the pneumatic regulator located behind the the power steering oil reservoir. The small air regulator supplies an "air buffer" pressure on the top of the hydraulic pistons at times referred to a "stabilizers". The stabilizers are the devices that are used when the steering wheel is turned to extremes, a micro switch activates these stabilizers "hydraulic pistons" to hold the rear of the coach up when the stabilizer system released the air pressure from the tag axle allowing for sharper turns. Not all coaches have this option.

If hydraulic oil is leaking from the pneumatic regulator, one or both of the stabilizer pistons are bypassing leaked hydraulic fluid. Meaning, the seal in the piston that separates the hydraulic oil (lower) from the air side (top of piston) of the piston has faulted. Their is an hydraulic oil reservoir mounted in front of the rear end differential pumpkin on the bulkhead facing towards the front of the coach. At least, that is where mine is located.

The air buffer is designed to hold a positive pressure on the top of the stabilizers under normal operation

This device is mentioned in the Prevost Service manuals. Again, it is an option and not all coaches have this feature.

This may be a brief description of a complicated system, we can chat more of this at the Austin Rally.

Hector

[JIM CHALOUPKA]

There are only three places that use the type of oil you say is leaking, trans, power steering and stabilizator. You indicate you believe it is not the trans. I suggest you check the power steering reservoir to make sure it is full. If it is in fact full it will be stabilizator oil, the device you say is disconnected. So don't worry too much the mess will only be about one gallon and then stop.

I would though be sure the regulator is not ruptured in a way to allow you to loose air big time, not sure how the parts pieces of the deal all interplay, but if the air is no longer needed, see to it that it is terminated safely and not just left to be.

Better yet get the stabilizator repaired and you will fund it desirable and useful.

JIM

[flloyd]

Thanks Hector,

Your description seems closest to my observation.

The good news is that the leaking has subsided, perhaps as Jim suggested, due to the complete loss of hydraulic oil.
I'm looking forward to finding out more, as soon as I can figure out how to access the area. Then, it's time for a general
clean up, something that will have to wait another month or so, for the weather here in AZ to improve :-)