I'm trying to leave Clayton New Mexico. Turbos on. New exhaust manifold. Start it up to go and run engine runs good but for some reason the air pressure is building very slowly. Replace the haldex air system and the D2 Governor this past spring. It's taking 10 to 15 minutes to build up to a hundred 10 lb. What are my possible problems to look for? Do not hear any air leaking anywhere so it's not like a major hole somewhere.
Larry,
If you are not hearing a significant leak, then the air governor is the first place to look. Under $25 and easy to replace.
Sure it could be something else but with no significant air leak, a reasonable place to start.
Is it possible for the filter or desiccant has plugged and slowed the air supply?
Larry
Loose belt? Have you checked your engine air filter? Tap on the governor with a hammer.
That may draw air from the boosted area of the intake to the compressor . Or the intake hose may be connected in the wrong place. Maybe a plug is still on the hose or something along that line. '
Also a the relief valve mayb e leaking back into the air supply.
Look closer at the work that has just been done .
Phred, belts aare good, air filter new and checked for good tight fit. And did percussive persuasion.
Mike, the first thing I did was check that nothing was damaged from the other work. Can't hear any leaks. When I shut down the engine, the air pressure holds. It just takes forever to build up. After running the pressure up and down several times it seems to build slightly faster, but not like it did coming in.
I was running 110 pds when I arrived but it was different when starting up today. Keep the suggestions coming.
Thanks, Larry
Check your book and trace the compressor inlet line. It wil be filtered and may or may not come from the pressure part of the air inlet. It would build slower than in the past if it is connnected to the pre turbo area.
Mr Wolfe10 is correct I would replace the air governor not much money easy to replace I had one give me some problems last year I had a spare changed it out built air good.
I had this issue twice. The first time my drier purge valve didnt close fully and was letting enough air out that it took a long time to fill. The second time my air line from the drier to the tank alongside the engine had a hole worn or melted thru it where it rubbed against the exhaust where it wasnt well secured. A new line made at the local hydraulic shop in five minutes and I was in business. Its tough finding leaks over the roar of the engine, but both times I found it by running my hands over the hose or spraying soapy water at fittings, lines, etc.
That was the first thing I checked was The Purge air valve. No leakage there. No leakage there. Started the coach up this morning it seemed to build air quicker but still not as good as it has in the past. Finally have the coach running where we can get out of Clayton.
Not sure if the M-11 has it but the Cummins manual for the 12 valve 8.3 suggests you clean/check a air tube coming off the air compressor for blockage(coked oil in the line),may be something to research.What about a worn air compressor?
In my world it doesn't matter if you replaced the D2 yesterday, for $25 I'd install my spare and be certain everything is all right with the D2.
That being said, when was the last time the air compressor's cylinder head was pulled and the unloader valve cleaned and the seal replaced?
And as John44 said always check the lines for obstructions.
Personal side note here: On my Siata restoration project, after I replaced the brake master and wheel cylinders and purged the air from the rear brakes, I discovered the front flexible lines to be totally blocked. So much for cutting a corner. Four (4) new flex lines and I'm good to go.
Not a steel hammer !! Brass is good.
I get the hammer part but what would a loose belt tell you about air pressure,air compressor is gear driven!!!
Gear driven compressor, did not realize that, mine is belt drive
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. Decided to start with the easy stuff first. Pulled the dessicant canister and coalescent filter. The dessicant seemed very heavy, weighed in at just under 6#. The coalescent filter seemed oily with some oil &/or oil surrounding it. I have new filters coming on Monday. My question at this point is, how heavy should the canister be? When the new one arrives, I will weigh it to check, but was wondering if anyone knew off hand.
Also, I haven't checked, but where does the air compressor get it's air supply from? I would think that it is filtered somehow before getting to the compressor, but didn't know where the supply was from.
Thanks,
Larry
Hmmm, since it holds air ok once it builds up could the problem be at the 6-packs? Did you look at the exhaust ports to see if they're exhausting air while the pressure is building up from first start-up?
Reference below says the air comes from the intake manifold. Have to admit I haven't actually looked to find the source on my engine.
Air Compressors (http://beamalarm.com/Documents/air_compressors.html)
That is a common source of air for the air compressor.
The advantages:
Uses the main engine's air filter vs have to service two separate filters.
The air is already cleaned, compressed (by the turbo) and cooled by the CAC before it goes to the compressor.
Since it is serviced by the intake, is it possible that the cartridges filled up w/debris from the turbo? I haven't checked the six packs, but will when I get the new filters and restart the engine. Before I left Clayton, neither I nor the mechanic (younger man with good ears still) heard any leaks, at least not large enough to be audible. I'm certain that I have some small leaks through out which I will have to chase with soapy water, but nothing blatantly obvious.
Larry
Do one fix/repair at a time or you'll never know what the problem was.
Can't take credit for this thought, but since Mike R. hasn't posted in the thread yet
Haldex air dryer isolation valve (https://www.foreforums.com/index.php?topic=17590.msg118159#msg118159)
If you have a Haldex dryer, perhaps this internal valve could be the problem?
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
On ours the isolation valve is on the side of the drier,found one on Ebay.
Depending on how old your drier is you may want to consider an exchange one and keep your filters for spares.
My bad. I was thinking of the purge valve. I replaced the entire dryer system in March. That didn't replace the isolation valve. Like you said, 1 step at a time.
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.
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
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.
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 (https://www.foreforums.com/index.php?topic=28212.msg246145#msg246145)
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.
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.
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
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