ISL air compressor -- only getting 27PSI on gauges

[gonecampin1]

Smart mover, replace the dryer

[Dale70]

For those that think the governor will be so easy to replace I am adding a few pictures I just took.

First on left is bottom of compressor -- notice that large hose across it
Next on right is where that hose leads back to --- Hydraulic pump.
That pump supported to engine but driven from end of air compressor
Third is distance between hydraulic pump and end of starter.

I believe I can faintly see the governor somewhere above hydraulic pump
Therefore to get at the governor, at the very least, it would mean removing the hydraulic pump and getting into the tight space above it.

From above you just see the fuel system of course, and there is NO access from the frame rails side at all

I am therefore hoping it is the dryer which could arrive later today

thx Dale

[mackwrench]

What a shame. Too bad coach builders don't give 2 craps about engine/driveline maintenance.
When I was a dealership technician, if a coach was to drive up, we'd all get real busy....and people wonder why, ha-ha

Is it a rear radiator? Buy chance can you see the air compressor, the governor might be mounted on either the side or top of compressor.

[Dale70]

it is a SIDE radiator Allegro Bus - Model 40QSP -- 400 ISL HWH Hydraulic levelers, 7500 Onan, Freightliner Chassis but with Independent Front Suspension (ZF german), front disc brakes, standard Allison 3000.

(rear radiators are not on my "desirable" list)

They did some things well --- both fuel filters are right at rear door --- easy to get at --- some other things NOT so good.

Suspension seems wierd to have ONE ride height controller on front with independent suspension and TWO ride height controllers on the back with a solid axle ??????????? (my Eagle on the Spartan is just the opposite of course)

I would put ride equal to the Eagle on smooth or average roads, probably one small step down on rough roads, but not at all bad.--- steering is excellent (easily one hand type) with ZERO freeplay, less effect of sidewinds and trucks passing than Eagle. Braking is superb. I think acceleration is slightly slower than Eagle but I was having fuel issues at low RPM. Gas mileage seems to suck on ISL compared to ISC, but as mentioned I was having some issues and had to keep RPM high and speed up. I stayed before Diesel Particulate Filters (07 emissions) so no purging and no replacement of a $2000 filter.

I have about 900 miles seat time so far.

My seat of the pants evaluation of suspensions, some with only limited test drives/

ALL 2007-2008 vintage, worse to best

Solid Axle freightliner
Liberty - Spartan Solid Axle
Roadmaster 88RS (still a solid front axle)
Freightliner IFS
Startan IFS

YES --- I AM TEMPORARILY HIGHJACKING MY OWN THREAD -- that is life.
I will get back to dryer when it arrives

talk soon --- Dale

[Wild Card]

Originally Posted by Dale70

it is a SIDE radiator Allegro Bus - Model 40QSP -- 400 ISL HWH Hydraulic levelers, 7500 Onan, Freightliner Chassis but with Independent Front Suspension (ZF german), front disc brakes, standard Allison 3000.

(rear radiators are not on my "desirable" list)

They did some things well --- both fuel filters are right at rear door --- easy to get at --- some other things NOT so good.

Suspension seems wierd to have ONE ride height controller on front with independent suspension and TWO ride height controllers on the back with a solid axle ??????????? (my Eagle on the Spartan is just the opposite of course)

I would put ride equal to the Eagle on smooth or average roads, probably one small step down on rough roads, but not at all bad.--- steering is excellent (easily one hand type) with ZERO freeplay, less effect of sidewinds and trucks passing than Eagle. Braking is superb. I think acceleration is slightly slower than Eagle but I was having fuel issues at low RPM. Gas mileage seems to suck on ISL compared to ISC, but as mentioned I was having some issues and had to keep RPM high and speed up. I stayed before Diesel Particulate Filters (07 emissions) so no purging and no replacement of a $2000 filter.

I have about 900 miles seat time so far.

My seat of the pants evaluation of suspensions, some with only limited test drives/

ALL 2007-2008 vintage, worse to best

Solid Axle freightliner
Liberty - Spartan Solid Axle
Roadmaster 88RS (still a solid front axle)
Freightliner IFS
Startan IFS

YES --- I AM TEMPORARILY HIGHJACKING MY OWN THREAD -- that is life.
I will get back to dryer when it arrives

talk soon --- Dale

my IFS has 1 height control on front and 2 in back.

FYI I see no governor in that pic. If its not on compressor its remote mounted. Follow small lines back from dryer to find. My rig is rear rad ISL and governor is mounted on compressor 1/2 hidden by frame rail. If I ever replace I will remote mount.

If I were you I would do the same.

[Dale70]

Wild Card --- what RV do you have that you are talking about?

[Wild Card]

Originally Posted by Dale70

Wild Card --- what RV do you have that you are talking about?

2009 Itasca Horizon Freight Shaker XCL chassis

[1doodadd]

Just my 2 cents. Driven rigs for over 45 years and had the same thing happen to me on the road. Turned out to be the dryer going bad allowing oil and sediment from the dryer to flow downstream the dryer to a One Way Air Valve before tank plugging it and not allowing but very minimal air to pass. That was a Very Expensive check valve repair

[Dale70]

Well the new Haldex dryer is installed and I am pleased to report all is working well. Got home with the dryer at about 2:30 and by 3:30 I was ready to fire it up, check that it was working in the driveway, then go for a test drive. I think transfering a few fittings from old to new dryer took as long as the installation,

Dryer purges at about 135 and comes back on at about 95-105
it takes only about a minute and a half to go from the alarm (70PSI) to purge.

I am very happy that it was not the (hiddden within the bowels of the beast) governor.

I do have a small leak at the front ride height controller that I will have to eventually fix --- but that is very minor compared to not being able to move the RV as it wouldn't build up enough pressure to overcome the spring brakes.

Very pleased.

Once again thanks for the guidance and direction as I was ruminating a course of action.

thanks again --- Dale

[Gordon Dewald]

Happy it worked out fairly easily it appears.

[RRBattani]

See if you can seat the purge valve with a screwdriver. The rebuild kit is somewhat inexpensive, and easy to do.

[GORD CURRIE]

DALE 70,
YOUR GOVERNOR,
Is most likely the problem and they are cheap about $20 or $30 bucks. bolts onto the Air-compressor and any Semi Truck dealer parts department will have them. Look for the model of your Air compressor or take your old one off to get one same bolt pattern with AIR PORTS AND LINE PORTS SAME SIDES. Most likely a Bendix Westing House Compressor & Governor. The Governor has an internal leak which is opening up the compressor Valves to soon which won't allow the Compressor to build Air to proper pressure. I assume you have been draining your Air Tanks to get rid of Water which happens to build up at nights from cool down causing water condensation to happen and does so on all Air Tanks on all Air systems. The Air dryer works for the wet Tank or first Tank Air is pumped into from the Air compressor but does not work on the other 2 or 4 tanks depending on Air Bag suspension or spring suspension. Those other Tanks if optioned will have water spitters on them to get rid of water but should also have drain valves my Travel Supreme has cables to pull and drain air. WHEN YOU DRAIN YOU CAN TELL BY SOUND HOW MUCH MOISTURE YOU HAVE IN THE TANK. Most often No Air [FAULTY GOVERNOR] I carry a spare governor with me always learned in my early Trucking years.

[twinboat]

Originally Posted by RRBattani

See if you can seat the purge valve with a screwdriver. The rebuild kit is somewhat inexpensive, and easy to do.

He fixed it.

[twinboat]

Originally Posted by GORD CURRIE

DALE 70,
YOUR GOVERNOR,
Is most likely the problem and they are cheap about $20 or $30 bucks. bolts onto the Air-compressor and any Semi Truck dealer parts department will have them. Look for the model of your Air compressor or take your old one off to get one same bolt pattern with AIR PORTS AND LINE PORTS SAME SIDES. Most likely a Bendix Westing House Compressor & Governor. The Governor has an internal leak which is opening up the compressor Valves to soon which won't allow the Compressor to build Air to proper pressure. I assume you have been draining your Air Tanks to get rid of Water which happens to build up at nights from cool down causing water condensation to happen and does so on all Air Tanks on all Air systems. The Air dryer works for the wet Tank or first Tank Air is pumped into from the Air compressor but does not work on the other 2 or 4 tanks depending on Air Bag suspension or spring suspension. Those other Tanks if optioned will have water spitters on them to get rid of water but should also have drain valves my Travel Supreme has cables to pull and drain air. WHEN YOU DRAIN YOU CAN TELL BY SOUND HOW MUCH MOISTURE YOU HAVE IN THE TANK. Most often No Air [FAULTY GOVERNOR] I carry a spare governor with me always learned in my early Trucking years.

It was the dryer purge valve, fixed.

Read some of the posts past the first one.