View Full Version : Another Source of Air Leaks

09-04-2014, 04:33 PM
I sure wish I had a detailed drawing of our air system. While at Prevost-Jacksonville I was able to look at the illustrated parts breakdown for the air system. It is so much more detailed than the air system drawing many of us have downloaded from Prevost's site. Even with the detailed parts drawing it takes some work to understand both the air flow and the logic of the air and electrically operated solenoids.

I like many have leaks in my aux air system. It's no big deal to me as I don't need aux air when parked and the leaks are minor. Well, I just fixed one of my leaks in the aux air system, even though that's not the problem I was taking care of. With the ignition key off I was getting a pretty good leak from the electric air solenoid for my level low system. The middle solenoid toggles based on whether the ignition switch is on. When on the air suspension system is controlled by the Prevost leveling system. When the ignition is off the suspension is controlled by level low or auxiliary leveling system. In my case, that would be the HWH controller that effectively takes over from the Prevost manual Level Low system.

The solenoid is available in two parts. One is the physical air control valve. This comes in two variants, normally open or normally closed. The other part is the electromagnet that controls its position. The physical control valve was all I needed. The leak was fixed and I now hold aux air for days. I'm sure I have other minor leaks, but they are of far less concern than they were.

While on the topic of air leaks, they are normal. The push-on connectors that are widely used on our coaches and throughout the industry have an allowable leakage rate per DoT or SAE standards that range from .5psi/min to as high as 5psi/min. When you consider the number of connectors we have, even using the most stringent DoT or SAE standards, we shouldn't be alarmed when our air system loses its air over the course of several days. For those that replace all of their connectors seeking a leak-free system, that's great. There's certainly nothing wrong with that, it's just that it's not necessary if the rate of leakage is minor.

Here's a picture of the manifold for the suspension system with the 5 electrically triggered solenoids. The one in the middle is the one I replaced. There's also a picture of the solenoid and a view of the air passages and o-rings. This part is about $40 from Prevost.

09-04-2014, 08:24 PM
Gill, Is it important that one lock clip points a different direction than the other four ?

09-04-2014, 08:48 PM

I'm sure you know the one turned the other way is the 12V solenoid. The others are 24V.

Of course I'm kidding...were you?

Joe Camper
09-04-2014, 10:22 PM
That's 10 points deducted easy Gill.

Sheesh............ cant even believe u posted that like that.

Get Ben to photoshop that picture

When U R in there with the soapy foamy water looking aroun take care NOT to allow excess fluid to pool and soak past the small square rubber spacers between the solenoids and the wire end terminal that is held to them with a small machine screw.

Because u will hear bacon frying and u will make smoke.

Where else can u find this kind of candor.

What else. The entire manifold is a steal at under 400 what were they separate Gill?

09-04-2014, 10:22 PM
Like Horse Shoes, they should all point up for Luck!

Joe Camper
09-04-2014, 10:29 PM
Somthin else. See the Red Tips in Gills photo. Those R where the air exhausts. Well if u ever notice rust color around those exhaust ports.

DRAIN THE WATER FROM THE AUX COMPRSSOR WATER SEPORATOR. Or worse yet if u don't have one get one.

I can not recall how many level low manifolds R exhausting rusty water that gets it that way.

Next in line would be rust under the exhaust port for the front ride height valve. on IFS its dead center and easy to spot.

09-05-2014, 07:22 AM

Each solenoid, pictured in the lower part of the picture, is $40. The entire manifold setup is over $700.

Joe Camper
09-05-2014, 07:49 AM
If U R confident of that cost of the complete manifold then Prevo has recently raised that price by approximately double what it was last time a customer bought 1. That was about 6 weeks ago.

That cant be right.

09-05-2014, 11:12 AM
Although the parts guy didn't look the part up he stated it was about $750 with some confidence. He also spouted off the part numbers for the solenoids as though he sells them all of the time. The five complete solenoids would be pushing $400 alone. Although I would expect a price break on the complete assembly, that doesn't always hold true.

$500 is certainly better than $750, but $40 trumps them both :-)

Joe Camper
09-05-2014, 02:53 PM
That past post is a bit confusing Gill.

Just to clarify that entire norgren air manifold as an assembly in your first photo is under 400 from Prevo just like its been.

09-05-2014, 03:28 PM

I looked up the complete 5 port manifold price that says it includes the solenoids. The Prevost price is $343.27 for part number 641205. That's a deal when you consider a complete solenoid (electrical and mechanical) are about $80 each. I bet the new one has all the C clips aligned too ;-).

Just one word of caution. I understand some converters changed some of the five solenoids out for 12V units that look exactly the same as the 24V ones supplied by Prevost. Those aren't available from Prevost..

Joe Camper
09-05-2014, 04:55 PM
That's right some older (mid90s)Vantare have all been changed to 12 volt. Some Liberty just change 1 to 12 volt and leave the rest 24.