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RobVG
09-17-2010, 11:13 AM
C15 with a bendix compressor. Really slow to build up air. I was wondering if it could be something other than the compressor itself?

95zIV
09-17-2010, 11:16 AM
How old, and is it only the first time or anytime during the day?

RobVG
09-17-2010, 11:32 AM
It's a 2004 Kenworth with an AD-9 air dryer. Put a new compressor in 55,000 miles ago

It does it in the morning, I haven't asked the driver yet how it is during the day.

I't been sputtering when the dryer pops off

Rebuilt the purge valve. Still sputters

RobVG
09-17-2010, 11:52 AM
Quite a few edits to the post above.

Kgmz
09-18-2010, 01:42 PM
Have you checked the unloader and governor?

Tiny
09-18-2010, 02:20 PM
Soapy water and a paint brush will help LOL .....Little older so I see leaks with that before I hear them.Have had air tanks with pin holes due to water in the bottom .

Muffler Bearing
09-18-2010, 03:16 PM
Be sure to test the check valve under the dryer, when you pull the main line off the comp, air should only leak for a second or two then stop. The check valve looks like a big 90 degree fitting next to the purge valve, and it's tricky because it can blow all of it's guts out and just look like a regular elbow, but it needs a ball and spring inside it. And definately soapy water on the main line after it stops being braided metal line. It wont hiss but it will make a ton of foam if it's become porous. Good Luck, Tim

95zIV
09-18-2010, 05:34 PM
I had a airline collapse internally, the outside looked fine but the inside was blocked. It can be checked by pulling off the tank end of the hose and seeing how the flow through the hose is.

p.s. This was the line directly off the compressor to the first connection.

td25c
09-18-2010, 08:36 PM
About how long does the 2004 Kenworth take to build air RobVG ? I normally fire up my wreckers every saterday afternoon to make sure everything is operating normal.I thought about your thread today so I timed each truck setting at idle to build air at 120 psi.GMC with Detroit & hendrixson suspension took 4 minutes,so did my Peterbilt tractor.Now the W-900 wrecker took 8 1/2 minutes to air up,But it also has the 8 bag air ride suspension.I attribute the extra time to air up the bags.

RobVG
09-18-2010, 09:56 PM
About how long does the 2004 Kenworth take to build air...

I dont know. Holding it at a 1000, it got up to 90 in over 2 minutes and crept even slower after that. We have 6 other T-800's and they don't take nearly as long. At least with the suggestions I have some things to try on Monday.

(something I should of checked, is it starting from "0")

willie59
09-18-2010, 10:04 PM
Have you got a spare unloader governor you could put on it and see how its works? Usually one of the first things I do, they're typically rather cheap.

td25c
09-18-2010, 10:24 PM
Yup..check for air leaks & unloader valve as other members have stated.I started my trucks at "0" air.And with calls at odd hours in the day It takes me awile to build air & drink coffee before a run:D Keep us posted & good luck with it.

mitch504
09-19-2010, 03:53 AM
I had a airline collapse internally, the outside looked fine but the inside was blocked. It can be checked by pulling off the tank end of the hose and seeing how the flow through the hose is.

p.s. This was the line directly off the compressor to the first connection.

I had exactly the same problem with one of mine

tootalltimmy
09-19-2010, 03:03 PM
From the air brake pre-trip manual in B.C.

Check that air reservoir pressure builds from 50–90 p.s.i. (345–
620 kPa) within three minutes at a fast idle (1,000–1,200 r.p.m.).

ELROY521
09-19-2010, 08:41 PM
mine suppered when it let the air out for a year , finally had to get a over haul kit , check for leaks ,

DiamondLTruckin
09-23-2010, 01:31 PM
Check the purge valve. The deal that pops off air on the bottom side of the dryer. They can get gummed up if u let your filter go for a while.

RobVG
09-23-2010, 11:01 PM
Yeah, I put in a rebuild kit- new piston and orings. I think i'll bolt on a new govenor like ATCO said since it's cheep and easy and a good place to start. I've been buried latley and haven't got to it...

Sqeeky wheel get's the grease.:)

imbzcul8r
09-24-2010, 09:25 PM
I had one that was slow slow, put on a new compressor & still had the problem. It was the line between the compressor & wet tank under the cab, had a hole chafed but with engine running you couldn't hear it & as soon as you shut off the engine the check valve at the tank blocked flow back to the compressor & no leak to hear. Finally found it by putting shop air to the line out of the compressor & without the engine running it was obvious.

mitch504
09-25-2010, 08:54 PM
where did y'all get compressor rebuild kits or parts?

DiamondLTruckin
10-04-2010, 10:45 PM
make sure to clean out above where the purge valve goes it it can get pretty gummed up in there.

DirtHauler
10-16-2010, 03:16 AM
Did you figure it out?

RobVG
10-16-2010, 10:17 PM
Did you figure it out?

Well, we parked it since we have 2 spare trucks. I'll get to it later.

Funny thing happend Tuesday. Driver called and said there was something wrong with his truck and he was coming in. When he pulled in, his truck sounded like a toy machine gun. The pop off valve on the compressor was going off rapid fire. Must have been overpresuring but it goes off at 150 and the gauges said 130.

Replaced it and...same thing. Checked the line from the Govenor to the Unloader it was fine. Replaced govenor... no luck, same thing. Pulled the unloader out and found it was gummed up. Also the top 'o' ring was toast. Put in a new unloader and it works like a champ.

To be honest, I had to call Kenworth and pick their brains. But now I've got more knowledge to fix the other truck when I can get to it.

DirtHauler
10-17-2010, 05:21 PM
Well, we parked it since we have 2 spare trucks. I'll get to it later.

Funny thing happend Tuesday. Driver called and said there was something wrong with his truck and he was coming in. When he pulled in, his truck sounded like a toy machine gun. The pop off valve on the compressor was going off rapid fire. Must have been overpresuring but it goes off at 150 and the gauges said 130.

Replaced it and...same thing. Checked the line from the Govenor to the Unloader it was fine. Replaced govenor... no luck, same thing. Pulled the unloader out and found it was gummed up. Also the top 'o' ring was toast. Put in a new unloader and it works like a champ.

To be honest, I had to call Kenworth and pick their brains. But now I've got more knowledge to fix the other truck when I can get to it.

And more spare parts to swap out to troubleshoot. It works like that sometimes, when you put one thing off it comes full circle in a different way.

RobVG
11-13-2010, 12:07 AM
Finally got the truck in the shop today and I think I found at least part of the problem. The line from the govenor to the unloader had rubbed through under a clamp. Put 90psi and soapy water to it and it foamed pretty good. There was no audible leak.

RobVG
11-19-2010, 09:49 PM
I had one that was slow slow, put on a new compressor & still had the problem. It was the line between the compressor & wet tank under the cab, had a hole chafed but with engine running you couldn't hear it & as soon as you shut off the engine the check valve at the tank blocked flow back to the compressor & no leak to hear. Finally found it by putting shop air to the line out of the compressor & without the engine running it was obvious.

Between imbzcul8r, Tiny and Muffler Bearing, reading again what they were saying started to sink in.

It wasn't the governor or the unoader. When I realized if the line between the compressor and the air dryer is leaking, it won't have any pressure in it when you shut the truck off because of the check valve.

I left the truck running and crawled under it with my trusty spray bottle of soap and water. I foud a small leak between frame and tranny. I got up and went to the drivers side and leaned in behing the engine. I couldn't hear it but there was a pretty narly leak on the big hose going into the braided steel line. Lots of bubbles.

Long story short, the old hoses are laying on the shop floor waiting replacement.

I hope that's the only problem. We'll see

Thanks for all the help! :drinkup

Muffler Bearing
11-19-2010, 11:05 PM
yeah, nice job! I bet those old hoses were nice and stiff, like tree roots. And just think, when you're done with this, your compressor will last longer and you'll save fuel!

RobVG
11-20-2010, 12:24 AM
I bet those old hoses were nice and stiff, like tree roots.

:spongebob How did he know that!

:notworthy

RobVG
01-03-2011, 01:42 PM
Just wanted to follow up. Finally got around to putting it back together. It was the main airline from the comp to the airdryer.

It bubbled really good when sprayed with the soapy water but at 90psi I figure it should have been blowing out but those leaks were the problem. Thanks again for the help.