Skip to main content ↑ ↓
Topic: Air System Work (Read 830 times) previous topic - next topic

Air System Work

While taking on the air bag swap I also decided that the 32yr old dryer and governor should also be retired and while dumping the air tanks I noticed the wet tank vent valve leaked by a bit no matter how I positioned it so I ordered a new set of those as well. During the drive home from Tallahassee to Oceanside (2300miles) the only air system issue I had was my aux compressor pressure switch developed a pin hole leak in the diaphragm, but a couple weeks ago when we went beach camping (about 20mile drive) I noticed frequent unloading of the air system (every 10-15 sec), after searching that up here I saw both the dryer and governor could be the cause.
Bags swap has been covered here a bunch, about 8hrs start to finish; the dryer is a 2.5hr job, mostly related to getting the old fittings off and swapped on to the new dryer, it took all my horsepower to get the old fittings off...be sure and get them broke loose before you remove the dryer as there is no good way to hold it secure once it's out(thanks to youtube for that nugget of info). The governor swap is 20min. 
Wanting to know what the cause of my problem was I pulled my old governor apart and found the spool had been galling in the cylinder, I expect this was giving the intermittent unloading issue.
The continental bags are direct swaps...nothing to report on that, still waiting delivery of my new tank vent valves.
While leak testing I found a leak up at the valve set below the throttle, the small white covered bendix solenoid was leaking at the cover/electrical spade connection, the cover had screws holding it on so I tightened them and that solved the leak. What are those for? (I haven't pulled the air system drwg to find out myself yet).
Len Barron
1988 GV36 U280 3208T(250hp)/MT643
1972 Jeep Commando LS2/4L65e
2000 Chevy Express Hightop Campervan
LBZ Duramax /6sp Allison

Re: Air System Work

Reply #1 –
Quote from: len.barron –
While leak testing I found a leak up at the valve set below the throttle, the small white covered bendix solenoid was leaking at the cover/electrical spade connection, the cover had screws holding it on so I tightened them and that solved the leak. What are those for? (I haven't pulled the air system drwg to find out myself yet).
The thing leaking was one of the two "low air" pressure switches that monitor the air pressure in the supply lines going to the throttle valve and the treadle (brake) valve.  They are the sensors that will, when activated, set off the visual and audible LOW AIR PRESSURE warning signals at the instrument panel.
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: Air System Work

Reply #2 –
By the way, excellent sharply detailed photos in your writeup.  ^.^d

Good clear photos really help other members understand what you did, and make it easier to follow your commentary.

What is the blue stuff visible on some of the air line fittings?
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: Air System Work

Reply #4 –
The spool shouldn't have been making contact with the cyl. The O rings keep the spool off the cyl. I haven't seen galling on any of my spools. How bad was the O ring at that end of the spool?
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Air System Work

Reply #5 –
Quote from: craneman –
How bad was the O ring at that end of the spool?
it was pretty flat...well past its service life.
Len Barron
1988 GV36 U280 3208T(250hp)/MT643
1972 Jeep Commando LS2/4L65e
2000 Chevy Express Hightop Campervan
LBZ Duramax /6sp Allison

Re: Air System Work

Reply #6 –
Just a follow up on governor, I finally got around to firing up the engine today (was waiting on a new belt for the alternator/air compressor) and the new governor made a huge difference. I'm actually getting a full 125psi cut out pressure now. The best I saw before was 110psi, so I'm sure it unloading at 110psi then cutting back in a 100psi is the reason I was noticing the frequent unloads...the galled spool on the old governor was probably the cause of all that.
Len Barron
1988 GV36 U280 3208T(250hp)/MT643
1972 Jeep Commando LS2/4L65e
2000 Chevy Express Hightop Campervan
LBZ Duramax /6sp Allison
 

Re: Air System Work

Reply #8 –
Finally got around to changing out both (leaking) low pressure switches. Was able to find a good deal on a pair of actual bendix 228750 switches (rather than aftermarket). Video in this facebook link shows how badly one of them was leaking: Redirecting...
Len Barron
1988 GV36 U280 3208T(250hp)/MT643
1972 Jeep Commando LS2/4L65e
2000 Chevy Express Hightop Campervan
LBZ Duramax /6sp Allison