Haldex Purest Air Dryer install on M35A2 - questions about wiring, etc

clinto

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So I have a Haldex N50011H, which I believe is original equipment for MRAP and perhaps M939 series trucks.
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I'll be installing this on my '87 M35A2C.

After reading up on various threads (https://www.steelsoldiers.com/threads/air-dryer-for-an-m35a2.65682/), I have questions:

A. I looked all over the web and don't see a Haldex wiring connector out there. I'd like to build a jumper harness to get power to the heater. Are they out there? Image of my connector below.
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B. Does the heater on this dryer cycle thermostatically on it's own, or do I need to put a thermostatic relay in line? I see people here on SS saying if the heater is on all the time, it'll burn up quickly.

C, Jeepsinker did an excellent video on installation of a Haldex Purest on his A2 on his YouTube channel and he added a pressure relief valve. My unit has what looks like a pressure relief valve already on it. Is that what I'm seeing and if so, I assume that means I don't need a pressure relief valve plumbed in?
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Much thanks
 

Jeepsinker

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Looks like you got the hookup on a connector. You do need a pressure relief valve between the dryer and the compressor discharge. The relief valve on the case will only vent excess pressure in the case downstream of the dessicant package. The upstream relief valve apparently was an MWO on the A3 trucks to address rupturing issues when dessicant becomes compromised or falls apart and plugs the air path. At least, that's what I recall.
 

Jeepsinker

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Since this is opened back up...why put a big dryer on a deuce? They don't seem to have much air useage.
In my opinion, any vehicle that uses air in the braking system should have clean, dry air for that system. It's only sensible that the air pack will last longer and be less susceptible to failure if provided with good air.
 

MrMikey4026

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Your check wallet light will come on when you buy a cartridge for that thing!
I have a Pure Air sitting here waiting to install, the price of the cartridge made me think about it awhile!
Anyone have an inexpensive one?
Mike
 

simp5782

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Your check wallet light will come on when you buy a cartridge for that thing!
I have a Pure Air sitting here waiting to install, the price of the cartridge made me think about it awhile!
Anyone have an inexpensive one?
Mike
DQ6050 is the only filter for the unit.

Air dryer filters are under the replacement table of 24 months or 200,000 miles for light use trucks, 18 months for medium use or 12 months for heavy use like buses.

. If you have an air system that the compressor runs to compensate for leaks then it will be less time.

so the cost of the filter isnt that bad considering when it needs to be replaced time wise. probably longer with the use of the truck being low. watch ebay for good deals on them. I paid $40 for each filter i have.
 

clinto

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Looks like you got the hookup on a connector. You do need a pressure relief valve between the dryer and the compressor discharge. The relief valve on the case will only vent excess pressure in the case downstream of the dessicant package. The upstream relief valve apparently was an MWO on the A3 trucks to address rupturing issues when dessicant becomes compromised or falls apart and plugs the air path. At least, that's what I recall.
Thanks for the update. Yes, Simp went above and beyond helping me out on this. You have a recommendation for an inline PRV? I'm going to use all DOT air brake tubing when I do this.

Since this is opened back up...why put a big dryer on a deuce? They don't seem to have much air useage.
1. Airpacks are expensive and the cans are always shot because of the moisture
2. My USAF truck takes 2 airpacks
3. I think my airpacks are worn out, I'll be replacing them. With NOS. And I don't want water in my NOS airpacks.
 

tobyS

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I have to admit not spending much time on m35a3 air system and will have to before long ( in rebuild and 4x4). I guess I'll have 2 brake air packs and air assist steering. I'll. Be putting on an auxiliary tank for some tools too. Do you have any idea on the quantity of air or would that depend on brake use?
 

clinto

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Was able to grab the same air dryer I believe
Where were you able to find the haldex connector? Did you follow jeepsinkers mounting or do something else?
I got a takeoff connector from Wes and I am copying Jeepsinker's mounting plan. In the process now.
 

clinto

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Cool
Mine comes next week so hoping to do the same
Worth just cutting off the connector and putting packard on it?
Sure. I do that on most of my modifications to keep everything uniform.

The other choice is something modern like a GM weatherpack connector.
 

Dunkeye11

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Have you ordered your air lines? I was on McMaster looking at sizes and was assuming I should pick the push to connect style lines in 1/2 for supply and 3/8s for signal? Anyone already know the style and size of connectors I need?
 

simp5782

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Have you ordered your air lines? I was on McMaster looking at sizes and was assuming I should pick the push to connect style lines in 1/2 for supply and 3/8s for signal? Anyone already know the style and size of connectors I need?
You need to use steel jacket parker 919 or copper. Heat from the compressor discharge will melt and make the nylon line weak and it will blow.
 

Jeepsinker

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Use this discharge line from the compressor to the frame. You can use 1/2" plastic air line from there back to the dryer, and from the dryer to the tanks. Signal line only needs to be 1/4" from the governor to the compressor and from the governor to the unloader on the dryer. Use 3/8" everywhere else.
 

Jeepsinker

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I was following your video connecting to the copper line that enters the air tanks from the compresser with a plastic line
I don't recall that. May have been a repair I was doing before the swap. All my lines are plastic now except the fuel supply line from the tank to the primary fuel filter.
 
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