A1R - Haldex PURest™ Air Dryer.... turbo protection valve?!?

[GeneralDisorder]

I have serviced the dryer cartridge on my truck.

In my reading and travels I come across this "turbo protection valve".

I can't find much in the way of information related to this.

The usual scumbags and others list this part:

Turbo Protection Valve Kit for PURest Air Dryer

Shop the Turbo Protection Valve Kit for PUREst Air Dryer at Midwest Military Equipment. Ensure optimal performance and protection for your turbocharger with this high-quality kit.

midwestmilitaryequipment.com

What's the story with this valve?

Rick

 

[MRAP DREAM GIRL]

Rick have you figured out where that goes do I need one maybe for my truck. I'm assuming it may be he's not one of your favorite places

 

[GeneralDisorder]

Rick have you figured out where that goes do I need one maybe for my truck. I'm assuming it may be he's not one of your favorite places

Part of the problem is I'm not sure exactly what the valve does - it seems to be there to shut off the inlet port during a purge signal from the governor. I'm not entirely clear on the mechanics of why blocking off the inlet to the dryer during a purge is desirable..... the compressor is already unloaded and not pumping any air so I'm not visualizing what effect this has....

I do believe your AD-9 has something similar - seems to be integral to the purge valve piston:

Rick

 

[Castle Bravo]

A few years ago when I was rebuilding my M916 air dryer, I came across a mention of a turbo protection valve and similarly wondered what that was all about. Here is what I recall - It is a valve to prevent the intake charge in the intercooler from being used as the air to purge the desiccant pack of moisture. The idea behind this is to not have a reduction in engine power (by evacuating the intake charge/boost pressure) during the air dryer purge.

 

[Castle Bravo]

Rick have you figured out where that goes do I need one maybe for my truck. I'm assuming it may be he's not one of your favorite places

It's a component of the air dryer, within it in all the examples I've seen.

 

[Castle Bravo]

A few years ago when I was rebuilding my M916 air dryer, I came across a mention of a turbo protection valve and similarly wondered what that was all about. Here is what I recall - It is a valve to prevent the intake charge in the intercooler from being used as the air to purge the desiccant pack of moisture. The idea behind this is to not have a reduction in engine power (by evacuating the intake charge/boost pressure) during the air dryer purge.

The part I left out is the path from turbo to air dryer. The condition that the turbo protection valve prevents happens when the air path from the turbocharger all the way to the air dryer is open, through the air compressor. On a vehicle where the air compressor intake is not fed from the engine intake manifold/intercooler, or is not turbocharged, the turbo protection valve is unnecessary, though probably present, usually being a component of an off the shelf air dryer.

 

[Ronmar]

Well that IS the purge valve core. The significance comes into play if the compressor inlet is connected into the engine air intake system between the turbo and manifold. This config makes the air system more efficient when the engine is loaded as it delivers pre-charged air(20+ PSI) from the turbo to the compressor. But when the compressor unloads and the dryer is purging this opens an escape path for turbocharged air to escape thru the dryer, reducing engine performance… This valve design seals that escape path during a purge.

The LMTV pulls the compressor air from between filter and turbo so it doesn’t serve any real purpose on this config…

 

[Ronmar]

Also of note in that video(and most air system diagrams) is that 100% of the dryer output air passes thru the supply/wet tank To reach the service tanks. The purpose of this is that dryers fail, so hopefully you will find water in the wet tank BEFORE it gets to the service tanks to contaminate the rest of the brake system.

They did NOT do this on the A0 LMTV. They appear to have fixed it either on the A1 or A1R. On the A0 the dryer outlet flows to a T fitting on the wet tank and the other leg of that T flows on to the service tank Check valves Like in this first pic. So during a charge cycle, you are charging all 3 tanks simultaneously. With the smaller size of the supply/wet tank, I would say less than 1/4 of the air consumed by the brake system ever sees the inside of the wet tank… I believe S&S did this in error as it flys in the face of common sense… The A1Rs I have seen appear to be plumbed correctly.




On an A0 it is easy enough to fix as seen in this second pic…

 

[GeneralDisorder]

On my A1R the compressor is fed air from the manifold which is after the turbo and intercooler. Don't know if this was a change to the A1 or the A1R but definitely the compressor is post turbo.

 

[Ronmar]

Interesting… The A0 is pre turbo, I havn’t played with the A1R too much and hadn’t noticed that “feature” It appears that they did the same thing with the A1… So, go turbo protection valve!

 

[GeneralDisorder]

I haven't noticed any power loss.... but then when it's under boost I can't hear the compressor so..... for the price of them it's probably worth just replacing it if I'm taking it apart to inspect.