No air, need help

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No air, need help

April 02, 2019, 06:55:03 pm

Got the coach running for the first time this season. Let idle for about 20 minutes. Coach never raised up. Checked the gauges, hadn't moved off of 20 lbs. Tried the air line drain valve in front of left rear tires, only got minimum air flow. Maybe 5-10 lbs. I can't hear any leaks anywhere while the engine is running. Besides the search here on the forum which I will be going through tonight, what/where should I be looking at/for?

Once again, thanks in advance,
Larry

Re: No air, need help

Reply #1 – April 02, 2019, 07:04:25 pm

Go back to the air compressor you will see an aluminum valve with a small hose going to it. That's the d2 air governor give it a small love tap or 2 with the engine running, it controls the air compressor. Use the search function at the top of the page and type in D2 air governor lots of posts on it.

Re: No air, need help

Reply #2 – April 02, 2019, 07:05:27 pm

Larry,
In order from simplest to more complicated;
Brake tank drains up front, Popet valve on wet tank, D2 governor, air drier,. With the engine running, I would start by placing my hand under the purge valve to see if I could feel air coming out. If the answer is no, then I would make sure the valves in front on the air brake tanks are not open, the safety blow off valve on the wet tank (Very unlikely) And then I would put your spare D2 Governor In. You do have a spare governor, right?
Don
Edit: Sorry about the punctuation, doing this on my phone in bright sunlight and so can barely read it.

Re: No air, need help

Reply #3 – April 02, 2019, 07:19:11 pm

Would start at the source and trace thru the D-2 regulator and the air drier,the source being the engine driven air compressor,see
if you can locate a line coming off the compressor and see if it's pumping air.

Re: No air, need help

Reply #4 – April 02, 2019, 07:21:09 pm

When I had a similar problem I discovered that the problem was the air dryer. If your air dryer hasn't been serviced in several years then that could be the problem. Suggest searching the forum for "air dryer."

Re: No air, need help

Reply #5 – April 02, 2019, 07:30:20 pm

Thanks everyone. I will be burning up the search function tonight, so if your forum useage is a little slow, I'm sorry. I have the manuals here at the house so I should be able to locate all the items mentioned. After work tomorrow I will begin the hunt. This learning curve sure is fun, isn't it.

Don, no sweat on the punctuation. I wasn't sure I had a D2 governor let alone a spare one

Larry

Re: No air, need help

Reply #6 – April 02, 2019, 07:39:42 pm

D2 $15-20. Love tap means smack it lightly with hammer or cresent wrench

Re: No air, need help

Reply #7 – April 02, 2019, 08:22:28 pm

If that doesn't work take the plastic cone shaped cover off loosen 7/16 lock nut and screw in the pressure adjustment screw one or two turns CW and one or two turns CCW

Re: No air, need help

Reply #8 – April 02, 2019, 08:34:19 pm

Just had the same thing this past week on mine. I decided to go cheap first and changed the Governor...no dice so I started digging more and found the bottom of the air dryer venting out as fast as it was pumping air so wasn't gaining pressure. Changed out the dryer 300 dollars and bingo it fixed my problem. Good luck

Re: No air, need help

Reply #9 – April 02, 2019, 09:16:50 pm

Thanks everyone. I've spent the last 3 hrs searching past posts and it seems likely the dryer, but I will check the D2 governor first. I have no records from previous owners of dryer being worked on, so I fear for the worst. Even if it is the governor, I will at least check the dryer for the maintenance procedures from this forum. One of the fun things with owning an older coach is that you get to play with all the various systems and learn so much. Also being able to repair and keep running these wonderful machines is satisfying.

Since my printer has a better memory on paper than I do in between my ears, I have printed up nearly 100 pages of info derived from here. Posts, PDF downloads, pictures etc. All I can say is thank you all from all the posts who help add up the collective knowledge base. Couldn't have this coach without it.

I'll report my findings as I go.
Thanks again,
Larry

Re: No air, need help

Reply #10 – April 02, 2019, 09:21:54 pm

Been replacing our air dryer annually. From what I've read here and told by others, if air dryer fails it can send "gunk" throughout the air system with the potential for multiple component failures in the air system. May be pricey to replace but ultimately save money.

Re: No air, need help

Reply #11 – April 02, 2019, 09:27:12 pm

Yes I've read the horror stories also over the years. Didn't know where to start looking but have a better idea now. I have only put on 1000 +/- miles on the coach since I have bought it, so I hope that I don't have the dessicant problem. Never had anything come out of the drain valves when I checked them.

That work thing keeps getting in the way, but not for to much longer.

Larry

Re: No air, need help

Reply #12 – April 02, 2019, 09:33:53 pm

Quote from: Flatfisher53 – April 02, 2019, 08:34:19 pm

Just had the same thing this past week on mine. I decided to go cheap first and changed the Governor...no dice so I started digging more and found the bottom of the air dryer venting out as fast as it was pumping air so wasn't gaining pressure. Changed out the dryer 300 dollars and bingo it fixed my problem. Good luck

Same story for me last Sept...

dan

Re: No air, need help

Reply #13 – April 02, 2019, 10:48:54 pm

I changed my dryer last year with a Re manufactured unit I got at Napa. If your somewhat good with a wrench you can do it... I did mine at my storage spot.. and if it does go bad it is not "gunk" but powder that goes thru the system, you will see it if you drain the wet tank... ask me how I know that.. from what I've read the desiccant filter needs to be changed every 2 or 3 years under normal use and the whole assembly every 5 or 6ish years. Here's a pic of mine after I took it off the coach.....

Keith

Re: No air, need help

Reply #14 – April 03, 2019, 06:11:56 am

It looks like mine that is still on the coach. Will look this afternoon.

Larry

Re: No air, need help

Reply #15 – April 03, 2019, 08:30:06 am

Quote from: ohsonew – April 03, 2019, 06:11:56 am

It looks like mine that is still on the coach. Will look this afternoon.

If you have the same dryer, then you could try running the engine again and see if you feel air flowing out bottom of dryer. Will tell you if this is the source of your massive air loss. If YES, replace dryer with a new or reman, and yer good to go.

Re: No air, need help

Reply #16 – April 03, 2019, 09:29:34 am

While I believe the problem is compressor /D2/ dryer, start at the D2 and make sure that it gets pressure from the compressor.
If it drove to the storage lot with air , it is likely that the dryer worked fine. Fire it up and feel the dump valve for air, if none, move back towards the engine , loosening the feed line, check for air, etc.
If your D2 is mounted directly on the compressor, take a picture, remove it, change it , try the system again. If the new one has no change. Remove it and blow softly through a rubber hose into the compressor ports. A little WD 40 or CRC will lube the valves.
If all of these parts seem to work, follow the air line from the dryer to the first tank.

Re: No air, need help

Reply #17 – April 03, 2019, 09:35:17 am

Think were all telling ohso the same thing in different words.

Re: No air, need help

Reply #18 – April 03, 2019, 09:43:22 am

Quote from: Protech Racing – April 03, 2019, 09:29:34 am

If it drove to the storage lot with air , it is likely that the dryer worked fine.

In my case the dryer worked fine when it was put into heated storage for the winter-- but didn't work properly in the Spring. After checking the other portions of the system, the replacement dryer resolved the issue.

Re: No air, need help

Reply #19 – April 03, 2019, 11:14:12 am

Here's where the D-2 governor is on a 97.
jor

Re: No air, need help

Reply #20 – April 03, 2019, 11:38:03 am

I had a failing d2 controller on our coach when we bought it.

Pumped the brakes till all the air was gone on the dash gauge.

Started motor. Coach built pressure after that.

Replace d2 valve. Adjust to 110/130 psi for better brakes

Re: No air, need help

Reply #21 – April 03, 2019, 06:39:09 pm

Ok guys here is what I got. Started the coach, air gauges went from 0 to 30 and stopped. Never got above 30 with engine running for about an hour, both low and high rpm. Tried persuading the d2, which is mounted directly on the compressor behind the AC compressor. Nada. Foune the air dryer located lower left side of engine between the engine dipstick and side rail. It is a Haldex, couldn't see any numbers. Got underneath and located the plastic purge valve. I assume from Bob's picture that it is supposed to be open to the ground. Lots of dirt, grease and looks like it had something looking damp. Could be condensation from our weather, not sure.

In one of the posts I pulled up from Twig 4 years ago it says "Remove the screw on filter on the top and see if it airs up. If not, putt out the smaller filter down inside and see if it airs up. If not, uh oh. It's the dryer. If it does, it's the filter(s)." If I understand this, the filter canister will screw right off without removing the complete dryer? I'm sure this would take a strap wrench which I didn't have at the lot.

I'm thinking about making up one of the dryer bypass couplings and seeing if it will raise the pressure. When I crack the pit cock for the wet tank, by the DS rear wheel. I get a steady flow of air, probably the full 30#. Since the coach has settled down, I can't quite reach the two front tanks to check for pressure.

More researching tonight, that's for sure.

More comments appreciated.
Thanks,
Larry

Re: No air, need help

Reply #22 – April 03, 2019, 07:09:15 pm

Did you put your hand under the purge valve while it was running to see if you could feel the air coming out? It is pretty easy to tell, not a subtle thing at all if it won't build more than 30lbs.
Don

Re: No air, need help

Reply #23 – April 03, 2019, 07:23:58 pm

Yes, I took a rag and cleaned it up some. Didn't notice any air coming out at all. Not near the pressure from the wet tank valve.

Larry

Re: No air, need help

Reply #24 – April 03, 2019, 07:27:00 pm

The thinking that leads me to the following recommendation is this: Unless you know when the air dryer was last serviced/replaced then you can expect it to fail at an inconvenient time and place. Therefore, eliminate that possibility and proceed with additional troubleshooting if needed.

My recomnendation is to make sure the coach has zero air pressure and then carefully remove the iair dryer while carefully documenting where each line connects to the dryer. Then make a bypass out of pipe to connect the two main lines together and cap any control lines. This should allow full air pressure to move the coach and/or do additional troubleshooting. Use the information found on the dryer to order a rebuilt replacement.

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