AHC Help PNW area

[ktmracer01]

Part numbers:

90301-70003 - Pump cover gasket (3 bolt)
90311-10001 - motor seal
48977- 60010 - Motor coupler (the link between motor and pump rotors)
90301- 06012 - o-ring between the internal pump and pump manifold (photo #2)
48901-60010 - internal pump (complete assembly)

 

[IndroCruise]

@suprarx7nut I had a chance to pull the pump apart earlier this week and was surprised by the following:

1. Very simple design and easy to disassemble. 10mm socket and 1 allen wrench for all hardware to pull it apart.
2. The amount of sludge and the gelatin-like gunk that was in it after most of the fluid had been drained and the number of times the system was flushed before it was removed. (at least a dozen times. @Eltestro can correct me if I'm wrong)
3. The internal pump gaskets are not easy to source <- this could just me being lazy.

I haven't been able to exactly identify the cause of the pump failure, but based on the gelatin nature of the sludge that was in there, I fully expect that to have played a major role in the pump not cycling fluid properly. I did a visual inspection of all the gaskets and I couldn't find any tears or obvious defects that would cause it to suck air. And, the pump wasn't leaking any fluid before pulling it from the truck.

After cleaning it up a little bit, there was evidence of wear on the motor coupler and also some light scratches on the inside of the pump cover. Some type of debris went through it, but I can't find anything that would have caused the scratches yet.

The gaskets that I ordered just arrived, but as I pulled it apart, I realized I didn't have a "full" rebuild kit ordered. As I pulled things apart more, I realized the internal pump assembly has five (5) additional o-rings/gaskets; one that looks a little like a house, and two small round o-rings, and also two (2) metallic gaskets that I haven't located on a parts diagram.

I was able to source the internal pump as a complete unit online and should arrive sometime in mid-August from partsouq. At this point, probably in this pump for around $200.00USD with all of the gaskets and internal pump.

I'm starting to suspect that this may be a leading factor to most people having issues with their AHC. If the system hasn't been flushed regularly, it would be very easy to have deposits build up in the pump. Also, the AHC fluid is hygroscopic (absorbs moisture), so if the vehicle sits for a long time or if it isn't flushed regularly, it will eventually absorb some moisture. Depending on the climate, that could be a little or a lot. Just my 2cents.

Seems like this would be a good place to start for people that are having AHC issues before committing to new globes, etc. Obviously depending on DTC's that present themselves.

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Here are a few more pics of the AHC Pump internals to add to your collection. Some of my pics at the links below also draw attention to the tiny strainers within the pump sub-assembly. The brass (?) ferrule marking the top of the strainers also is visible in some of your pics.

Post #67 by @BullElk at AHC pump out? - https://forum.ih8mud.com/threads/ahc-pump-out.1226629/page-4#post-13401098 shows pictures of a VERY clogged pump.

Posts #69 and #70 by @IndroCruise at AHC pump out? - https://forum.ih8mud.com/threads/ahc-pump-out.1226629/page-4#post-13407297 and onwards shows pictures of AHC Pump disassembly and also show the tiny filters (strainers) within the Pump. Pump disassembly and cleanup of the pump and easing out the pressed-in filters (strainers) with a pick and/or backwashing are all straightforward -- made easy when the motor/pump/tank assembly already is removed from the vehicle.

Even with the decision to replace the pump, disassembly of the existing pump is a good idea -- as you have done. It is better to know how much jelly-like 'gloop' is in the system (caused by very old fluid), particularly at the tiny internal strainers, when installing a new pump and risking another blockage.

The FSM diagrams also suggest that there is a similar strainer in the Return Valve after the Pump, before the pipe leading to the Control Valve Assembly. The Return Valve is within the milled metal block to which the Pump and Motor are attached on either side. There is a 8mm Allen head cover on the underside of this block which can be removed -- which I have done, but I have yet to figure out how to pull out the Return Valve and check its strainer (if there is one).

 

[ktmracer01]

@IndroCruise thanks for posting this. I had no idea there were other strainers in the system. That helps answer even more questions about what could have prevented the pump from cycling fluid properly.

I'm still confident that the goop build-up is at the heart of most of the AHC system failures, but not limited to AHC globes and height sensors.

 

[ktmracer01]

@Eltestro this sounds like your pump before we swapped it...

 

[Eltestro]

@Eltestro this sounds like your pump before we swapped it...

Exactly!