M932a2. Air dryer blowing air

[SETOYOTA]

Picked up a truck on Monday. (M923a2) Went over it for the short 9 mile ride home. Everything seemed fine. Fluids, air pressure, tires, etc.

about halfway into the trip I start losing air pressure. By the the time I get home air pressure warning is on, both primary and secondary are going down but at different rates.

today I have a chance to look at for a bit. It will not build pressure . The air dryer is blowing air out the bottom and I'm fairly sure this is my problem .

is there some sort of relief valve in the air dryer?

Is there a rebuild kit for the dryer?


Any suggestions?

 

[Suprman]

It is a relief valve. It is supposed to vent at 150 psi. Napa had ones that size that vent at 165 psi. There was a guy selling surplus kits with the proper replacement valve and the haldex air dryer cartridge which you should replace anyways, for around 100 bucks. You can cheat and put a plug in place of it for now but watch your pressure big your ppv sticks you will blow a line or worse without that valve. I would be willing to bet your truck sat for some time with moisture in the air system. If you replace the haldex cartridge dump some air dryer alcohol in there when you have the cartridge off.

 

[Suprman]

There is also an expello valve in the center of the air dryer it is where the air dryer automatically vents moisture.

 

[SETOYOTA]

Is that what I need? The air is blowing out of the bottle top looking piece

http://www.amazon.com/Haldex-Midland-DQ6026-General-Service/dp/B00480MQTG

 

[quickfarms]

You could also have a bad air compressor governor or an air leak.

 

[Suprman]

That is the air dryer service kit and it is what you need. The little brass thing in the pic with the red bottom is the safety relief. They go bad and leak. The filter cartridge hand screws on if it is leaking from around there you can hand tighten it. The black plastic piece to the right in the pic covers the expello valve. It is at the bottom center of the air dryer. I believe the c pieces in the kit are for servicing this valve.

 

[SETOYOTA]

I will also look at the air governor . That's the valve on the firewall correct?

The air dryer is blowing air at avery high rate this has to be a major part of the problem .

Suprman I think you are correct in that the truck has sat for a while. However no moisture came out when opening the drain valves on the right side but now there is very little air to expel any moisture.

I'm not sure if the kit I posted is the exact one for my air dryer but it sure looks like it. I need to get the model number off the one on my truck.

 

[Suprman]

It should not be blowing air out from the air dryer. The safety vent should open if over pressure at 150 psi but will close again as pressure comes down below 150. The expello valve vents moisture when built up but not continuous. The governor is after the air dryer if air is coming out of the air dryer not caused by over pressure then the governor is not the issue. If you have an a2 with abs then that's your kit.

 

[SETOYOTA]

Yep a2 with abs.

 

[Suprman]

Order the kit. So is air coming out of the center expello valve or the brass pop off valve?

 

[SETOYOTA]

Not sure. But I think it the expello valve . You can feel the air by placing your hand over the black plastic cover with the bottle top looking opening on the bottom of the air dryer.

 

[Suprman]

I believe it can be taken apart there are 3 or 4 screws holding the cover on. I wonder if a bit of dirt or debris is stuck in this valve and it cannot seal closed properly. I would take it apart and clean that valve out. The air comes out of the compressor and into the air dryer then out to the tanks so proper air pressure is not making it to the tanks.

 

[SETOYOTA]

Think I will try that tomorrow. Thanks for the help. I will update with my results

 

[SETOYOTA]

Not exactly sure what I did. Took it apart cleaned it up and put back together. now builds to 120 psi and holds pressure.

i still plan to get the kit and service it.

thanks for the assistance . This is what is great about the forum.

 

[Suprman]

Great probably just a little dirt somewhere. I like to set my pressure around 135 if the ctis is filling air it gives you a little leeway the ctis will stop filling around 115psi and wait for pressure to come up again.

 

[SETOYOTA]

Still holding about 100 psi 8 hours after shut down. How do you set the pressure?

 

[quickfarms]

If you take the cap off the air compressor governor there is an adjustment there

 

[Suprman]

What do they go up to when driving?

 

[ichudov]

What do they go up to when driving?

Normally to 125 PSI.

 

[SETOYOTA]

Not quite to 125