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dodges1515 · 06-17-2016, **(Subject: Primary air tank won't build air )**

Which air dryer assembly do you have? If it is a AD-IS it has a built in manifold that directs compressed air to different locations on truck and the holes are quite small,(like 1/4 inch)if your hose/line from compressor has internal issues of breaking down it can plug these holes.It is fairly easy to take apart for inspection.Seen this several times.
Also it really doesn't take much of a air leak along with a marginal compressor to get behind on any particular tank psi.
Bendix online has all the specs on what your compressor should perform at and also an exploded view of your dryer assembly.

Post your dryer type and also compressor type it will help a lot,many people on forum have lots of experience in this area that can help.

Good Luck!

jesse20 · 06-17-2016, **(Subject: Primary air tank won't build air )**

(06-17-2016 )Rawze Wrote: I had a bad leak on the solenoid block in the frame next to the transmission that would only leak until it got down to 90 psi once. The entire solenoid block backplane was cracked.

are you talking about this one? when i bought the truck at 495,000 miles and it had a slow air leak i put a zip tie and ran fine, ill will double check

Rawze · 06-17-2016, **(Subject: Primary air tank won't build air )**

(06-17-2016 )jesse20 Wrote: are you talking about this one? when i bought the truck at 495,000 miles and it had a slow air leak i put a zip tie and ran fine, ill will double check

Yup, that ne. Mine was cracked. I think ice formed in it one cold winter and cracked it.

trucklogger2 · 06-28-2016, **(Subject: Primary air tank won't build air )**

(06-17-2016 )in2trux Wrote: Sounds like the compressor itself, sticky unloader. You could try wd40 in the intake of the compressor but you have to open the intake line at the compressor head.
I would also check the purge valve on the drier while it's building air. I've had them stick open and not be able to build air. Leveler valves for the airbags can also bleed off allot of air but they should be on the secondary.

I was thinking about this, but where does the shi#t go if you do this and then run the truck..... That's a little scary. Wouldn't it be better to remove the head and then clean the gunk off? There could be a scary amount of shi#t. That shi#t is like coal. Maybe I'm missing it, but thanks for any answer.

Rawze · 06-28-2016, **(Subject: Primary air tank won't build air )**

(06-28-2016 )trucklogger2 Wrote:
(06-17-2016 )in2trux Wrote: Sounds like the compressor itself, sticky unloader. You could try wd40 in the intake of the compressor but you have to open the intake line at the compressor head.
I would also check the purge valve on the drier while it's building air. I've had them stick open and not be able to build air. Leveler valves for the airbags can also bleed off allot of air but they should be on the secondary.

I was thinking about this, but where does the shi#t go if you do this and then run the truck..... That's a little scary. Wouldn't it be better to remove the head and then clean the gunk off? There could be a scary amount of shi#t. That shi#t is like coal. Maybe I'm missing it, but thanks for any answer.

Actually I think you are supposed to remove BOTH lines, intake and output, while doing this. I could swear I read a cummins procedure for it too a long time ago, if memory serves me right.

trucklogger2 · 06-28-2016, **(Subject: Primary air tank won't build air )**

(06-28-2016 )Rawze Wrote:
(06-28-2016 )trucklogger2 Wrote:
(06-17-2016 )in2trux Wrote: Sounds like the compressor itself, sticky unloader. You could try wd40 in the intake of the compressor but you have to open the intake line at the compressor head.
I would also check the purge valve on the drier while it's building air. I've had them stick open and not be able to build air. Leveler valves for the airbags can also bleed off allot of air but they should be on the secondary.

I was thinking about this, but where does the shi#t go if you do this and then run the truck..... That's a little scary. Wouldn't it be better to remove the head and then clean the gunk off? There could be a scary amount of shi#t. That shi#t is like coal. Maybe I'm missing it, but thanks for any answer.

Actually I think you are supposed to remove BOTH lines, intake and output, while doing this. I could swear I read a cummins procedure for it too a long time ago, if memory serves me right.

Thanks,i'll look for it on troubleshooting tree maybe.

Nilao · 06-29-2016, **(Subject: Primary air tank won't build air )**

I used marvel mystery oil to help dissolve the carbon on a sticky unloaded valve. Got my friend up and running and he didn't have another issue for over a year. It started sticking again so he opted to replace it with a reman compressor at 870k miles.

PS I did remove both the intake and exhaust ports of the compressor and ran it till no more oil came out. The filter will remove residual oil but it can be saturated if hit with large quantities at one time.

dbl overdrive · 06-29-2016, **(Subject: Primary air tank won't build air )**

(06-17-2016 )in2trux Wrote: Sounds like the compressor itself, sticky unloader. You could try wd40 in the intake of the compressor but you have to open the intake line at the compressor head.
I would also check the purge valve on the drier while it's building air. I've had them stick open and not be able to build air. Leveler valves for the airbags can also bleed off allot of air but they should be on the secondary.

This works, Cummins actually has a service bulletin on this very situation only they uSe tran fluid. Wd 40 works good to.
As part of the egr tune up, I do it on every truck. Also on de mandated trucks as well.