Community Forums

NorCal Hal · 05-19-2010, 10:23 AM

While at the last week NorCal ACA Fortuna rally Tom Polk brought up the subject of servicing the air dryer (A-D) the Alpine coach uses. After crawling under and cleaning off my air dryer I found my coach has a Haldex PURest model N4253F dryer.

Tom had been told that the filter needs to be replaced when you see oil dripping from the bottom opening of the A-D. After not finding my model number on the Haldex website I called Haldex (800) 643-2374 / (816) 801-2727 and spoke with Tim Shaw in their customer service dept. He said that DA34140 is the P/N they use for our model A-D and that the desiccant cartridge should be changed every other year on a motor home or when you see drops of water, not oil, coming from the bottom. When I mentioned waiting until you see oil dripping out (mine is COVERED with oil) he said "we hope to catch it BEFORE that".

The replacement service kit for my model A-D (your model may be different) is DQ6050...$ 108 at Napa.there are probably better prices, I haven't shopped around yet. Tim said they should be available at most truck supply companies.

Tim send me the following info and said the "multi treatment cartridge" - kit is easily replaced. Looks like you remove the four bolts securing the top mounted cover, not the V band around the unit, grab and rotate the cartridge a fraction of a rotation to unlocks some tabs then lift out the cartridge. There appears to be an O ring seal under the cartridge which may, or may not, come out with the cartridge.

Here are the Fact Sheet and Installation and Maintenance sheets Tim sent me.

Harold

takepride · 05-19-2010, 09:32 PM

Crap! You guys keep coming up with more things I have to service. Good thing I consider this a hobby. If my car needed this much service, I'd trade it in annually.

NorCal Hal · 05-20-2010, 04:05 PM

I got seven prices, no two the same for the Midland / Haldex DQ6050 ranging from $ 59.95 to $ 145 plus tax... Who says you get what you pay for - (I HATE that expression!) These prices are for the same EXACT part made by the one and only company that makes it. The price differences reflect the mark up each company adds...Not quality, service or any other thing!

The BEST price was from Jack Young Company of Allston, Mass. (617) 782-1250...The $ 59.95 sale they had has ended but I bought two for $ 97.42 each.

EngineerMike · 05-25-2010, 06:30 PM

Thanks to Jerry Davis, I received and forwarded on the servicing instructions for the air dryer, so they should show up in the Alpine Tech Library under Chassis & Brakes at a computer near you soon.

Jerry also asked my opinion about servicing the dryer. I'm adding it to my annual inspection as to oil at the exit port, and to change the desiccant cartridge at 5 year intervals or sooner if needed. Old Forester appears to have reached the "if needed" point around the 5 year mark. Other coaches don't seem to get the oil blow by problem by that time.
FYI I crawled under an 04 last week, and the oil mess was taking over. I figure that's a 7 year old desiccant cartridge, combined with an excessive oil use condition by the compressor.

chadandapril · 05-25-2010, 07:59 PM

I just replaced mine Napa was the cheapest I could find $80 I didnt notice until I put the new one on that the old had quit poping off Be sure to empty the air tanks before taking the old filter off

OldForester · 05-25-2010, 08:49 PM

EM: I think I reached mine at the 3 year mark if not earlier. My coach is about 4 1/2 years old and I've owned it 4 years this month. This problem has been there for over a year, but most noticeable in the last year. I think it's an annual inspection item for sure, if not every time one opens that access door, to see if the air dryer is spitting oil. The Cummins dealer said it probably just needed the cartridge changed, but we will see when I get it over to Yakima in another month. I bought the cartridge from your recommended source so we will also see if that works.

D & D Rich · 05-25-2010, 08:51 PM

EMike, I too just crawled under my coach 2004 and it has a Bendix System Guard Air Dryer. While looking online for a disiccant cartridge under Bendix found where it said Warranty 3 yrs/ 350,000 and also said average life was 5 yrs. See a photo of mine but so far none of the numbers I took off my AD don't come up. So back under I go and assume the Alpine Position!!!

Emike what Air Dryer was on the 2004 you were napping under the other day?

EngineerMike · 05-25-2010, 09:09 PM

Didn't take notes on the air dryer other than the oily mess; was there checking the coach for rear suspension bolt size.

Old Scout · 05-26-2010, 08:11 AM

Based on this thread, I inspected the air dryer on my 2003 [never changed] and it is a Bendix[model AD-9, I believe]. Some telltale signs of oil by-pass but dryer seems to be functioning as designed. According to the Bendix Tech, the AD-9 is a very robust unit so unless you see/find oil or water in your air tank drain valve, the dryer is doing its job. Some oil collection around the exhaust port is "normal." Thats were it is discharged. [So--if it "aint" broke, dont fix it] Given our limited use of compressed air on the Alpine, I doubt that the dryer gets much of a workout. However, recharge kits/parts are available for the AD-9.
PS--as for "excessive" oil around the exhaust port, think I'd be more concerned about my compressor as the dryer is apparently doing its job.

Tom and Patty · 05-26-2010, 08:33 AM

My Bendix is 10 years old. When I dump air from the valve in the service bay, I have never even see a hint of moisture. But then again we have been in sunny San Joaquin Valley where the air is dry. I think mileage would be a factor, and we don't drive 12K per month

. St Louis (where the coach is)and Indianapolis (where the coach is going) might be a completely different story. I hear it is humid there

EngineerMike · 05-26-2010, 09:40 AM

If somebody raises docs for the service of the Bendix AD-9 unit, please forward them and I'll get them in the Tech Library as well. mike at fleming dot cc (not dot com).

Old Scout · 05-26-2010, 04:28 PM

EM--Bendix.com has a pretty good set of PDF data/schematics on the AD-9--not sure if there was any servicing instructions. Will see what they have the next time I get a chance.

jerry davis · 05-26-2010, 05:27 PM

A couple of questions about the air compressor.
1. It looks like it is gear driven by the engine. Does that mean that it is always turning and does not cycle on and off when the correct pressure is reached?
2. Is it lubricated by the engine oil? If so is that the blow by you find at the air release port on the air dryer? Why would engine oil make it to this area unless there is something seriously wrong internally with the compressor?

It used to drive me nuts when the air pressure released while idling in a dusty area. Dust would kick up onto the coach and into the engine air intake. I cut about a two inch long piece of poly tubing, clamped it onto the port and clamped a 90 degree plastic elbow on the other end. Now the air is directed towards the rear of the coach instead of onto the ground. Simple change that sure makes it nicer, at least for me.

EngineerMike · 05-26-2010, 05:55 PM

Jerry-
1. Yes. If you put a pressure gauge on your air chuck (and it works the same as mine), you'll see air pressure go up to a max level, then drift down, then up/down/repeat. I believe it hits the upper limit, then goes to bypass mode till the lower limit redirects added pressure to the frame & air tank. Mine cycles between 135 & 120psi.
2. Yes. Maybe. It wouldn't. Could be blow-by the rings in the compressor or it could be a leaking seal.