Skip to main content ↑ ↓
Topic: Building air pressure slow (Read 2129 times) previous topic - next topic

Re: Building air pressure slow

Reply #25 –
Quote from: ohsonew –
Made it home from Pueblo and now have time to chase down the slow air build up. When I started, it still took about 20 minutes to build to 90# at fast idle. While driving, the pressure would build up to 115-120 and hold well. If I had to brake or use the retarder, the tank would drop down to between 90-100#. It would then build back up to 120 with ease, so I made the 600+ mile trip home.

Thanks,
Larry

Larry I'm going to repeat myself here but have you replaced or cleaned the unloader valve?  The D2 governor operates the unloader valve to stop the air compressor from, well, compressing.  Depending on your compressor you may need to remove the cylinder head from the compressor to get at the unloader valve.
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.

Re: Building air pressure slow

Reply #26 –
Old Tool maker , I haven't made it that far yet. We got home 2 days ago and have cleaned out the coach and I have had to replace my desktop computer at the house, so that took most of yesterday. Luckily I am not in a time crunch so I can go one step at a time so I can figure out what the problem is, including the root cause.
I am starting simple and working from there. I plan on trying my spare D2 governor and verifying that I have no garbage in the lines or compressor.

Thanks for the reminder, I do appreciate your thoughts and knowledge.
Larry
Larry Warren
1996  U320 36' SBID "Lola" sold 2020
Build #4970
Motorcade #18318

Re: Building air pressure slow

Reply #27 –
Quote from: ohsonew –
I agree John.
Michelle, I thought so at first, but when the engine is running I put my hand over the exhaust and there was no pressure. Once it has built up to full pressure, I have heard the pressure relief valve blow off a couple of times.
Just got a call  from Transwest, my parts are in today instead of Monday. If only the mobile repair place was that efficient.

Larry

I think you're talking about the air dryer.  It's not a pressure relief valve, when the D2 switches the compressor from pumping to not, the air drier vents its pressure and blows the accumulated oil and water, in my case onto the tail pipe.
Art
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.

Re: Building air pressure slow

Reply #28 –
Quote from: Old Toolmaker –
I think you're talking about the air dryer.  It's not a pressure relief valve, when the D2 switches the compressor from pumping to not, the air drier vents its pressure and blows the accumulated oil and water, in my case onto the tail pipe.
Art


Art,
Your air dryer purges into the tail pipe??

Would love to see a picture of that one.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Building air pressure slow

Reply #29 –
Quote from: Old Toolmaker –
Larry I'm going to repeat myself here but have you replaced or cleaned the unloader valve?
Post linked below has some good photos of the "unloader valve" mentioned above by Old Toolmaker.

The whole thread wherein this post is contained is worth reading.  Lots of good info concerning air leaks and possible causes...

Air Leak
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Building air pressure slow

Reply #30 –
Quote from: wolfe10 –
Art,
Your air dryer purges into the tail pipe??

Would love to see a picture of that one.

When I was poking around and getting to learn my new toy, I was tracing out the brake system and I found the Bendix Air Dryer in the passenger side rear corner blasting down on the tail pipe.  And I went "I can wait to service that."

My to-do list is "dynamic."

On this Monday past I dropped the Siata fuel tank off at a radiator shop in Atlanta, GA for cleaning, repair and sealing.  I wanted to take the house, I'm glad I didn't because parking would have been interesting.  Lynn remembers driving through Atlanta on his way home from Texas and still has nightmares.  Then again the motorcycle cruises at pretty much any speed I desire and I knocked a few hours off the travel time.

Anyway I've been catching up on house chores, but my latest shipment of Siata parts arrived today so starting Tuesday I'll be installing rear axle seal on the Siata.
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.

Re: Building air pressure slow

Reply #31 –
Larry if your bad turbo was blowing oil, your air compressor intake downstream of the turbo would pick up the oil vapor on it's way to the engine, not sure if the air dryer filter could tolerate that much oil, as it's designed to vent water vapor primarily.. sounds like your pressure drops on brake application are excessive, try tank drains for water buildup from air dryer issues before it hits freezing.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Building air pressure slow

Reply #32 –
Just to follow up, I've been down sick for a week and wasn't able to work on the coach, the reason (and snow) for the delay. I finally got around to changing the dessicant canister and the final filter. The air pressure went up much faster this time. I'm not sure that is the total problem solved, but I will check when I go to take the coach for a spin tomorrow. The new canister which I bought was the 3# size instead of the 2#. I also noticed signs that water had been in the air dryer assembly. So I hope that the new dessicant will resolve the matter.
I had already checked all 3 air tank drains, and didn't get any water from bleeding them. I will check one more time tomorrow before taking the coach out and putting into storage.

Larry
Larry Warren
1996  U320 36' SBID "Lola" sold 2020
Build #4970
Motorcade #18318
 

Re: Building air pressure slow

Reply #33 –
Started the coach to put into storage. While it was building air pressure, I disconnected the electric from the house and made sure the bays were locked. By the time I got into the drivers seat, I was at 115#. Had to drive the coach 17 miles to dump the tanks and back. It never missed a beat. The tanks filled up quickly after using the brakes each time. It looks like problem solved.

Larry
Larry Warren
1996  U320 36' SBID "Lola" sold 2020
Build #4970
Motorcade #18318