I have a leaking ABS valve in my 1997 U295 - 40' that needs replacing, but have hit a roadblock and am looking for some direction here.
This is a valve that sits on the frame roughly over the front axle (not at the wheels) and controls/modulates the ABS action at the front wheels. It is a Haldex part number N4506A, listed simple in their catalog as an "ABS Valve" with a note "obsolete, no replacement available.
I did talk with Haldex Technical who confirmed the catalog note and suggested just replacing it with a standard air brake relay valve and even gave me a part number. However, three different entities in NAC balked at doing this suggesting that it may be violate DOT regs.
Has anyone else needed to replace a similar, old ABS valve? If so, were you able to find an ABS replacement or some supplier with new old stock? Or did you do something similar to the Haldex suggestion?
I appreciate any positive guidance anyone can offer.
I believe this subject has come up on the Forum in the past, but no solution was ever found. I seem to recall that one owner was advised to just "keep driving it with the leak", unless it exceeded DOT air brake leak-down limits. A quick Google search confirms your findings - the part is apparently obsolete. It is possible you might luck out and happen across a New Old Stock (NOS) unit for sale on eBay, but none show up at the moment. Looks to me like you have two choices:
1. Take the Haldex tech suggestion. Purchase the recommended alternative part and find a shop willing to install it, or do it yourself.
2. Remove your valve, take it apart, and see if you can rebuild it. I'm not clear on if this is a "air" system valve, or does it include some electronic bits? If it is just a mechanical valve, it is very possible that a good cleaning and a few new O-rings would return it to service. If it was me, I would at least try to take it apart and see what it looks like inside. But that's me...
Good luck with your project.
Billo, I had the same issue with our '03 U320. I remember it was a lot of searching on the internet trying to find a replacement. Long story short, I contacted FOT and they had a remand one in their shop that I bought. Try contacting Haldex/ Meritor and tell them what's going on. I still have my old one that I took apart to see if I could repair it and found out there's LOTS of small parts inside that fall out if you don't know what your doing! FOT might be your best bet as a starting point.
I thought I did a write up on it also.
Wouldn't an ABS valve only control one wheel instead of front axle? If it is the only valve and controls both wheels and one wheel loses traction it would cycle both wheels.
Maybe if you exercise the valve a few times it would help with that air leak?
Do the system test for the ABS system in your coach.
I think these valves go years and years without ever moving all the parts.
On my RV, the abs valves cycle every time the ignition is turned on....it's that clicking one hears.
Billo, check out my post from 2 years ago about my ABS problem. A couple of members gave some good info on where to start.
Craneman, there's air applied to those valves all the time.
That I understood, not knowing how the valve could control each front wheel independently is my question. A picture of the valve or schematic might answer that.
Here's what it looks like. This is my rear ABS valve
Makes more sense, actually three valves, main supply and right and left control valves. Which valve had the air leak? Doesn't look like the main valve has any electronics in it and might be easier to service.
Looks expensive!
Don
Thanks for responding. Your quote of "keep driving... " may have been from a post that I made about this in a thread of a slightly different topic. That was the response that I got at one Nac shop embellished with a comment of having seen others driving with even worse leaks.
Aside from the fact that the leak will inevitably get worse, I have a second issue. That is when parked the air system leaks down to zero in about 36 hours. In the event of an emergency I can't quickly move the coach until air builds.
Being full-time, without a place to park where I can work on the coach, I'm really boxed in as far as DIY in either option so I think that it boils down to finding a good mechanic willing to do the substitution.
I appreciate the responses and will check out your earlier thread.
From the searching that I have done the image that you posted looks like it is a Wabco valve. I believe that my Haldex valve serves the same function but houses everything in one block. I don't have a good picture because I optimistically figured the part number would get me what I needed ??? .
FOT wasn't much help in this case.
Thanks to all who responded. I will try the ABS test protocol if I can find.
Craneman, it is 3 pieces, center is the modulating valve,the others service the brakes. In my research two years ago I found some of the valves online but can't remember if they were the same part numbers. I don't believe any mechanic would repair one because of the DOT issues. The control valves on mine were leaking.
Don, was around $250.00 or so IIRC from FOT. Keep in mind that this valve was for my rear ABS system. Like Billo, my leaks weren't bad but wouldn't get better over time. I will take pictures of the ID plates and post them later.
For anybody interested, here's the part numbers for the ABS valves.
Wabco. 037. Wabco. 037. Wabco. 037
2102. 1902. 2802
37219500800. 47219500810. 9730110210
Control valve #1. Control valve #2. Modulating valve
Keep in mind this is for a 2003 U320 for the rear ABS system.
Richard - that is the same rear axle unit that has left me stranded ( almost) twice in 1 week. I am working with Dan's Diesel in Alexandria, Minnesota- they ordered the module from their supplier who sent the more updated one which does not work with my coach. Monday the correct module should arrive, be installed, and we will hopefully be on our way.
Bill O.- don't ignore. I am also full time and the first time I had a leak and it locked up the brakes on my toad because the diaphragm might have stuck open. I managed to get it unstuck by hooking, unhooking, fanning my brake pedal, etc. 2 days later it happened again and I could not build up air pressure. Called a mobile service guy who arrived a couple of hours later, showed him where the leak was but could not duplicate it. Decided to drive on until finding a truck area where I could get it worked on. Dan's Diesel is mainly trucks but also RV's, so that is why I am here now. I do not want to be stranded on the side of the road or lose my brakes while in the mountains.
Best of luck ^.^d