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medarwin · 12-09-2021, 05:42 AM

Hello all,

I recently did a complete rebuild on my air dryer (Haldex). After the rebuild, I continued to see working pressures between 112-120 PSI. The blow off was working as it should. This was just during system testing in the driveway. On the first trip out (1500 miles) working air pressures jumped to 131 a few hours in. They have stayed there and do not fluctuate except when air brakes are applied, then move right back up. I am also not hearing the blow off valve open to release pressure and expel moisture.

My question is, what should the working system pressure be? Is it possible that I need to dismantle the air dryer and look for a problem gain?

Any help is appreciated. Thank you.

twinboat · 12-09-2021, 06:13 AM

Quote:

Originally Posted by medarwin

Hello all,

I recently did a complete rebuild on my air dryer (Haldex). After the rebuild, I continued to see working pressures between 112-120 PSI. The blow off was working as it should. This was just during system testing in the driveway. On the first trip out (1500 miles) working air pressures jumped to 131 a few hours in. They have stayed there and do not fluctuate except when air brakes are applied, then move right back up. I am also not hearing the blow off valve open to release pressure and expel moisture.

My question is, what should the working system pressure be? Is it possible that I need to dismantle the air dryer and look for a problem gain?

Any help is appreciated. Thank you.

You should be looking at the small line on the air dryer.

If leaking, it won't purge and mess with the pressures.

bpu699 · 12-09-2021, 06:42 AM

My 2000 goes to 130 psi when I first turn it on, and vents pressure. As brakes are applied, it falls to 105 psi or so after 2-3 brake applications then quickly shoots back up to 130 psi or so...

medarwin · 12-09-2021, 04:10 PM

Thanks, I checked for leaks after the rebuild and there were none. However, OTR, I heard leaking air from that vicinity when stopped but it stopped quickly each time. I will crawl under again tomorrow and check that line.