RV Trip Planning Discussions

Go Back   iRV2 Forums > POWER TRAIN GARAGE FORUMS > Caterpillar Engine Forum
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
 
Thread Tools Search this Thread Display Modes
 
Old 11-29-2019, 12:33 PM   #1
Senior Member
 
lonfu's Avatar
 
Newmar Owners Club
Winnebago Owners Club
Freightliner Owners Club
Join Date: Mar 2016
Location: Kingman Az
Posts: 1,111
Brake Air Compressor

3126b cat on a FL chassis. Cat used a Midland 150-7638 air compressor with a serial # NT7028F 13 spline shaft with the hydraulic pump hanging off the back.

Looks like Hadex has bought out Midland now owned by the Fins. replaced air dryer and got oil and soot coming out out of the new dryer again.... Still getting plenty of air pressure but when it purges a huge mess on the toad....

Guessing the compressor seals have failed and the entire unit needs to be replaced. $2000. for the part. I can't even find a used unit to send off to a rebuilder.... anyone know a possible source for a used rebuildable unit???? anyone deal with this problem before?
__________________

__________________
May your black water hose never break!
lonfu is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 11-29-2019, 12:38 PM   #2
Senior Member


 
Join Date: Oct 2019
Location: Hoodsport Wa
Posts: 142
Try Brake and Clutch Supply in Seattle. Very knowledgable bunch of old timers work there. If they can't help you out, nobody can.

https://brakeandclutchsupply.com/locations.shtml
__________________

__________________
2000 Alpine 36 FDS #74058
"On the road to find out..."
Alpine36 is offline   Reply With Quote
Old 11-29-2019, 12:39 PM   #3
Senior Member
 
Join Date: Jun 2017
Location: Bryan Tx
Posts: 304
Lonfu, Didn’t I just see this unit on the classified for sale?
__________________
06 Beaver Patriot Thunder , 525 HP C13 Cat
MH 4000 Allison
42 ft Vicksburg, 4 slides
kenwyatt is offline   Reply With Quote
Old 11-29-2019, 04:14 PM   #4
Senior Member
 
lonfu's Avatar
 
Newmar Owners Club
Winnebago Owners Club
Freightliner Owners Club
Join Date: Mar 2016
Location: Kingman Az
Posts: 1,111
Quote:
Originally Posted by kenwyatt View Post
Lonfu, Didnt I just see this unit on the classified for sale?
yes, your correct, but i sold it in less than 12 days and it said the add expired in 14 days..... guess this is not true... marked it sold now...
__________________
May your black water hose never break!
lonfu is offline   Reply With Quote
Old 11-29-2019, 04:23 PM   #5
Senior Member
 
Join Date: Jul 2014
Posts: 19,671
How often does your air dryer purge. Frequent purging means the compressor is running to much and possable overheating. That causes oil blowing past the piston rings.

They have a 25% duty cycle.
twinboat is online now   Reply With Quote
Old 11-29-2019, 04:45 PM   #6
Senior Member
 
lonfu's Avatar
 
Newmar Owners Club
Winnebago Owners Club
Freightliner Owners Club
Join Date: Mar 2016
Location: Kingman Az
Posts: 1,111
Quote:
Originally Posted by twinboat View Post
How often does your air dryer purge. Frequent purging means the compressor is running to much and possable overheating. That causes oil blowing past the piston rings.

They have a 25% duty cycle.
My air compressor is splinned to the engine cam. It runs all the time, there is no clutch. The hydraulic pump that operates the fan and power steering is connected directly to the back of the pump and moves at the same speed as the pump. As the engine speeds up so do both the air compressor and hydraulic pumps. I've never timed the purge valve, but I did replace it when I replaced the air dryer and desicant filter.
__________________
May your black water hose never break!
lonfu is offline   Reply With Quote
Old 12-02-2019, 10:08 AM   #7
Senior Member
 
lonfu's Avatar
 
Newmar Owners Club
Winnebago Owners Club
Freightliner Owners Club
Join Date: Mar 2016
Location: Kingman Az
Posts: 1,111
Doesn't anybody have any info to help out with the brake air compressor???
__________________
May your black water hose never break!
lonfu is offline   Reply With Quote
Old 12-02-2019, 10:33 AM   #8
Senior Member
 
KanzKran's Avatar
 
Join Date: Sep 2018
Posts: 567
Quote:
Originally Posted by lonfu View Post
My air compressor is splinned to the engine cam. It runs all the time, there is no clutch. The hydraulic pump that operates the fan and power steering is connected directly to the back of the pump and moves at the same speed as the pump. As the engine speeds up so do both the air compressor and hydraulic pumps. I've never timed the purge valve, but I did replace it when I replaced the air dryer and desicant filter.
That's pretty standard. We have many larger Caterpillar engines where the compressor has a through-drive to the injector pump (older units). Obviously, it has to run at cam speed or it won't run.

But the compressors have a governor and an unloader valve, which results in the intake valve being held open when compressed air is not needed. It just sort of 'breathes', which requires little input power, and makes little heat, though the compressor is probably liquid cooled anyway. So the compressor spins all the time, but only does work when it's required to.
__________________
Tom & Jeri
2018 Coachmen Galleria 24T Li3
KanzKran is online now   Reply With Quote
Old 12-03-2019, 03:59 AM   #9
Senior Member
 
lonfu's Avatar
 
Newmar Owners Club
Winnebago Owners Club
Freightliner Owners Club
Join Date: Mar 2016
Location: Kingman Az
Posts: 1,111
Quote:
Originally Posted by KanzKran View Post
That's pretty standard. We have many larger Caterpillar engines where the compressor has a through-drive to the injector pump (older units). Obviously, it has to run at cam speed or it won't run.

But the compressors have a governor and an unloader valve, which results in the intake valve being held open when compressed air is not needed. It just sort of 'breathes', which requires little input power, and makes little heat, though the compressor is probably liquid cooled anyway. So the compressor spins all the time, but only does work when it's required to.
Ok, so found the compressor pump at Brake Systems Inc. in Portland Oregon. Have ordered one for a discount price of $1760.00 incl. ship and tax delivered to my door. Ow!!!!!!

50Lb old one is only good for a $100. core at Brake Systems as the one ordered is brand new. $450. to rebuild old one. Shipping makes the core worthless, guess I'll try to rebuild it when I have some time to fool around... I've rebuilt engines and such so why not a compressor.

I've never heard of a compressor with a governor before like that. I'm interested to pull apart the old one to see what it looks like. My Haldex air dryer has a valve that is replaceable that vents when the pressure hits a certain pressure to blow the moisture and oil out of the air dryer filter and to manage the top end air pressure, or so I thought.

Now to get the old unit out, it sits right next to the frame and looks like PIA to get out. Got a call into a local shop but they seem to be dragging their feet about getting me a quote. Looks to me that the hydraulic pump and compressor need to come out at the same time. gotta be about 75 pounds or so at least....
http://www.irv2.com/forums/attachmen...1&d=1575367099

http://www.irv2.com/forums/attachmen...1&d=1575367099
Attached Thumbnails
Click image for larger version

Name:	100_5038.jpg
Views:	6
Size:	183.8 KB
ID:	268511   Click image for larger version

Name:	100_5037 (2).JPG
Views:	6
Size:	631.4 KB
ID:	268512  

__________________
May your black water hose never break!
lonfu is offline   Reply With Quote
Old 12-03-2019, 05:16 AM   #10
Senior Member
 
Join Date: Jul 2014
Posts: 19,671
All air compressors have a governor.

They control the purge of the air dryer and unloads the compressor by opening the intake valves at the same time.

A simple leak at the governor will cause the compressor to cycle frequently.

At idle, engine running, the air dryer shouldn't purge more often then every 10 minutes or so. And that's with some leaks.

Replacing the compressor may stop the oil discharge but not fix what caused it.

Search out Midlands or Bendix compressor troubleshooting guide for causes if your problem.
twinboat is online now   Reply With Quote
Old 12-03-2019, 06:34 AM   #11
Senior Member
 
KanzKran's Avatar
 
Join Date: Sep 2018
Posts: 567
Quote:
Originally Posted by lonfu View Post
I've never heard of a compressor with a governor before like that. I'm interested to pull apart the old one to see what it looks like.
Compressors that stop spinning when air isn't needed don't have a governor, but they do have an unloader valve to bleed the air pressure off the cylinders for an 'unloaded' start when needed. But those that spin continuously, like on a truck engine, or larger stationary industrial compressors (piston and screw) use a governor that does what twinboat describes above, with some differences for stationary units. But same principle.
__________________
Tom & Jeri
2018 Coachmen Galleria 24T Li3
KanzKran is online now   Reply With Quote
Old 12-04-2019, 05:48 AM   #12
Senior Member
 
lonfu's Avatar
 
Newmar Owners Club
Winnebago Owners Club
Freightliner Owners Club
Join Date: Mar 2016
Location: Kingman Az
Posts: 1,111
Quote:
Originally Posted by twinboat View Post
All air compressors have a governor.

They control the purge of the air dryer and unloads the compressor by opening the intake valves at the same time.

A simple leak at the governor will cause the compressor to cycle frequently.

At idle, engine running, the air dryer shouldn't purge more often then every 10 minutes or so. And that's with some leaks.

Replacing the compressor may stop the oil discharge but not fix what caused it.

Search out Midlands or Bendix compressor troubleshooting guide for causes if your problem.
So, you must be talking about the little unit mounted on the side of the air compressor. looks to be about 2x5 inches and 2 air lines coming from it. I can see where this unit would "release air" good point, I'll look into it.

so, my air dryer fills up with oil and black soot. Black soot is most likely from the engine oil. The air dryer is doing it's job and purging every so often. I haven't timed it, but don't believe it is more often than you mention. I really notice it when I first start up, a big splatter of black goo and find it on my toad after just a couple of hundred miles.

When I looked at trouble shoot guides with my symptoms, they all pointed to the air compressor. As they age the seals leak and oil is drawn into the compression cylinders and blown into the air dryer and overwhelming it. Then the air dryer starts leaking the oil into the air tanks an so on down the line. I've replaced the air dryer and the "new $149 filter and desecant" unit is filled again with black goo after just a 600 mile trip.

My unit looks like the air compressor intake is taking the air directly from the crank case, I may be wrong about this can't seem to find any info that says other wise. It is possible that the air in the crank case could be contaminated so severely that it is ending up in my compressor but the engine has only 44k on it, so I tend to lean towards the compressor failure.

So, you are suggesting that somehow the air governor is causing the problem of oil getting into the air dryer? The air dryer is purging and the pressure gauges seem to be cycling 100 to 125 depending on the load of the brake and air bag system, I don't see how the air governor could be causing a problem.

Any one with some experience with this issue???
__________________
May your black water hose never break!
lonfu is offline   Reply With Quote
Old 12-04-2019, 06:15 AM   #13
Senior Member
 
Join Date: Jul 2014
Posts: 19,671
If its not purging often, the next checks are the intake and discharge lines.

The compressor intake should be running to the engine intake manifold, not crank case, where it draws in clean air from the engine air filter.
Any intake restriction will cause it to draw past the compressor piston rings.

Pull the compressor intake line off and it should be clean.

Next is the discharge line. When air is compressed it creates heat. That can cause a carbon build-up. That restriction causes the compressor to run hot.

The line could also be linked causing the same issues.

I'm not saying your compressor doesn't need to be replaced but you do want to find what caused it to fail.

44,000 miles is a short life for a compressor.
__________________

twinboat is online now   Reply With Quote
Reply

Tags
air, brake, compressor



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
AC compressor clutch issue, exam, & compressor replacement Civdiv99 Workhorse and Chevrolet Chassis Motorhome Forum 5 09-09-2018 02:01 PM
Air compressor Brake system el2pca Monaco Owner's Forum 5 02-25-2016 05:12 PM
Air brake compressor slow. frank1 Class A Motorhome Discussions 4 04-08-2013 06:17 AM
Brake Air Compressor Noise tiderv Class A Motorhome Discussions 4 11-18-2012 10:15 AM
Onboard Compressor vs portable compressor sgtjoe RV Systems & Appliances 26 12-18-2010 12:36 AM

» Featured Campgrounds

Reviews provided by


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 06:45 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
×