M923A1 Questions ???

[ShermHook]

Recently sold my M813 and with the fried battery replaced, the loose battery terminal adequately tightened, and decent weather this weekend I decided to make the delivery to the new owner. Since I need a little more seat time in a newly acquired 923A1 I had number 1 son drive the 813 and I provided chase in the 923A1. The delivery round trip was a little over 100 miles.

This trip reminded me of a few things - I have an air leak at the wiper switch and the passenger wiper motor and the horn did not work but I had been focusing on getting the 813 healthy and road ready for the last few months. It also reminded me how much different the 923A1 on super singles with the Allison drives compared to the good ole 813. Plenty of the Allison slamming from 1st-2nd, 2nd-3rd, and the real doozy down shifting from 2nd-1st. Many threads on adjustments here so I plan to study up this week. The trip was a success and the new owner of the 813 is as happy as a kid on Christmas.

So today I decided to get started trouble shooting the horn and wipers. The problem is I could not even get 10lbs of pressure to build up in the air system and the transmission would not shift into gear. Any chance these are related ? I could get some pressure to build up when I would rev the engine and then I think I heard an air release but since I had no helper with me it was impossible to determine the source. I have looked through the TM's and searched posts here and it seems like a good dose of trial and error is in order to find the source of the air problem. Not sure about the transmission just yet but one thing at a time unless somehow related. Any suggestions where to start ??

Kind Regards...

 

[Artisan]

If you make a way to pressurized the air system w/o the engine
running you can sometimes do said and hear a leak because the
engine is not running. I added a 1/2" brass tee at a PRV that is
before my Air Dryer, adding in a shrader valve so I can just
connect a shop air line to the truck and pressurize it w/o
the engine running so I can listen for a leak(s).

Others have suggested just pumping backwards from the right
rear Emergency gladhand but I believe a check valve will prevent
you from engizing it all.

If you KNOW you have some leaks FIX THEM NOW. Many small
leaks can = one bigger leak.

Pump the system up w/ shop air and engine off and listen...fix ALL leaks, that truck is NOT
safe to drive till you have it handled.

Make sure your gladhands are all holding air and their valves are OFF...
Make sure all your drain down ports on the PS are CLOSED.
Make sure all your valves under the truck are OPEN.
Make sure the E-Brake button on the dash is it the NORMAL posistion.

Get a CDL and Learn how to do a COLA test.

Govenor Cut In
Govenor Cut Out
1 Minute leak down test
Low Air warning light.

Do not listen to me... Bring it to a Certified Air brake mechanic.

 

[ShermHook]

Artisan,

No worries here about rolling unsafe. I always hit the COLA before I hit the road. Problem is, of course, without air pressure I can only do the "A". I like the brass tee and shrader idea. I could probably do a solo air trouble shooting job with that set up. Any insights into the transmission question? Somehow related or no?

Thanks!

 

[Artisan]

I think I would try to make it stop before go...

but;

The TC is not in NEUTRAL correct?

The trans has oil in it correct?

 

[Monkeyboyarmy]

Was it could outside today? Sometimes the valve on the bottom of the air dryer sticks open. With the truck running and all safety devices in place like wheel chalks, go underneath the truck and put your hand under the exhaust port of the air dryer. If air is leaking out, reach into the exhaust port with a small rod and push the valve back up to close it. Should build pressure. Also check trans fluid level.

 

[ShermHook]

Monkeyboyarmy you hit it out of the park on the air dryer valve. Valve closed = 120 psi. Probably time to change the desiccant filter.

The 10W trans fluid level was in the low end operating range. On a flier I decided to change the trans filter and replace the 10W with Dex III. I must say that made quite a difference. The combination of the old filter being partially occluded with crud and the marginal fluid level was probably enough to keep the transmission from shifting. I guess the road trip must have stirred up some gunk in there.

I took a drive around the compound and the shifts appear smoother. I need to get the air leak at the horn and passenger side wiper fixed first, but I can't wait to get it out on the road and see how it shifts 1-5, 5-1.

Thanks to Monkeyboyarmy and Artisan for the help!

 

[Stein12501]

ShermHook I too had the same problem and pulled the Haldex air drier and replaced the desiccant filter the collessing filter the dump valve and pressure relief cleaned it up and reinstalled it and it works fine. I ordered all my parts from Ryder Truck. Not a bad job for the weekend. Best of Luck.

 

[ARYankee]

ShermHook I too had the same problem and pulled the Haldex air drier and replaced the desiccant filter the collessing filter the dump valve and pressure relief cleaned it up and reinstalled it and it works fine. I ordered all my parts from Ryder Truck. Not a bad job for the weekend. Best of Luck.

I have the same issue but just haven't gotten around to fixing it plus I wanted to do some research into what I was tearing into first. I'll have to look through the -24p and see if it has a diagram of taking it apart. You don't happen to have a part number for the air dryer. I want to see if I can find some literature about it online so I can repair mine.

 

[Stein12501]

ARYankee if you search "Haldex Pure Air" you can get all of the .pdf files on the drier. If not let me know and I will scan them and send them to you. Their not real through but it will get you through it. If not they sell a factory rebuilt and you send them the old core. Good Luck!!!

 

[ARYankee]

ARYankee if you search "Haldex Pure Air" you can get all of the .pdf files on the drier. If not let me know and I will scan them and send them to you. Their not real through but it will get you through it. If not they sell a factory rebuilt and you send them the old core. Good Luck!!!

Ok. I'll try the search that you suggested and if I can't find anything, I'll let you know. I appreciate the info.