Sound the new style air dryer makes?

I just finished installing the new style air dryer on my M1078(A0). The old one made a loud "POP-RUSH" sound, and this new one makes a much softer "CREEK-HISS" sound. Is that how it's supposed to be? (I know, I know, trying to explain sounds in text, haha. But the previous sound was a loud pop and violent release of air in 1 second, and this new one is much more controlled and takes several seconds.)

Thanks!

Awesomeness said:

I just finished installing the new style air dryer on my M1078(A0). The old one made a loud "POP-RUSH" sound, and this new one makes a much softer "CREEK-HISS" sound. Is that how it's supposed to be? (I know, I know, trying to explain sounds in text, haha. But the previous sound was a loud pop and violent release of air in 1 second, and this new one is much more controlled and takes several seconds.)

Thanks!

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Which air dryer type did you install

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It's the "Haldex PURest". I didn't know there were more than the "old style" and "new style", sorry.

Your description of the sounds is accurate. The new style is not as loud and forceful sounding as the old model. I kept my old one as I like how it sounds and rebuild kits are inexpensive.

Awesomeness said:

It's the "Haldex PURest". I didn't know there were more than the "old style" and "new style", sorry.

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The haldex purest is a updated version of the haldex pure air plus. That did not come on LMTVs. There Is even a wabco air dryer that is the newest style to hit surplus. It's about 1/3 the size and weight of the purest dryer and around 60$ . It also has several different purge sounds it can make. The wabco dryer will even make a certain purge noise to indicate a leak in the air system or if it detects another abnormality in air flow thru it.

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I need to upgrade to the Haldex Purest. Looked in the SS Classifieds with no luck. Probably there somewhere but doing a search usually isn't easy! If you have one you can PM me. Thanks!

rd3war said:

Your description of the sounds is accurate. The new style is not as loud and forceful sounding as the old model. I kept my old one as I like how it sounds and rebuild kits are inexpensive.

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do you have a part number for the kit to rebuild the original dryer I kind of like it to

snowtrac nome said:

do you have a part number for the kit to rebuild the original dryer I kind of like it to

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RN60A is the midland/haldex number for the round "finned" style. around $40 on ebay.

While we're on the subject of air dryer purge sounds....I had about 2 tons on gravel in my M1078 last weekend driving along about 30 mph when my air dryer purged and simultaneously my park brakes partially applied creating a startling shuttering in the rear of the truck. Stopped the truck, inspected everything which looked fine and the very cautiously started driving again. Wondering if the air dryer purging was just a coincidence, I waited for the next release of air. It happened again, and again! It seems as though the park brakes are only momentarily affected by the purge but long enough to force a complete stop. Check valve? Load Sensing valve? Crazy!! I'm combing my schematics and could sure use some help on this one.

Went through the Tractor Protection valve last night and it seemed to be functioning properly.

thanks I will see if my napa traction store has it.

KGBruce said:

While we're on the subject of air dryer purge sounds....I had about 2 tons on gravel in my M1078 last weekend driving along about 30 mph when my air dryer purged and simultaneously my park brakes partially applied ....

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which air dryer? New or Old/Finned orrr?

Original "Finned" type. I neglected to disclose I was running the truck without the 90 degree dust cover (held in place with 3 small bolts) that covers the purge valve. I had recently removed and cleaned the purge valve because it had stuck open on an earlier occasion. I was leaving the cover off to monitor the valve.
Could the abscents of the cover allow enough of an increase in exhaust volume to drop the airline pressure enough to activate the low pressure switch?