HELP! AHC Pump Issue After Reservoir Drain/Refill
- Thread starter Wes Gardner
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Sorry for the slow response, I’m sure you’ve found it by now but..the power plug for the ahc is on top of the frame rail right next to the spare tire. It’s pretty easy to drop the spare and slide under the rear bumper to get to it. It’s a surprisingly large plug, probably 2-3 long, light gray. There is a smaller plug next to it that also goes to the ahc. I did not find it necessary to unplug that one unless removing the pump from the truck. I would leave the pump in if possible, but there’s really just a couple bolts holding the tray to the frame(it’s bolted to the tray), and you’ll have to unscrew the hardline to the pump. If you do decide to remove the pump, you do not need to pull the bumper cover off. I was able to reach the 2 hard to reach bolts with long sleeves and a 1/4” socket.
- Thread starter
- #23
When your clog broke how did you know? Was there a change in pitch from the pump?
I've ran the pump in reverse and forward about a dozen times now and there isn't much of a change. I plugged the pump back into the truck harness and tried starting the truck and there is also no change there.
I can tell sometimes when I manually run the forward it sounds like something gets stuck and the pump is working harder. The wires to my test clips get hot from the amp pull and I let it go, as this doesn't seem like normal pump behavior
The cavitation stopped once it had cleared. My pump sounded normal when reversed, and would run normal for a few seconds when I then changed flow direction. I repeated this process until it functioned normally.
A word of caution here. Absolutely do not use tech stream to run the pump for more than 10-15 seconds if you think there’s a clog. I did this. The pressure in tech stream jumped past 30 and it raised the truck to the shock travel limit. I’m talking 10-12” between the top of the tire and the fender well. It looked cool and was very stupid. How I didn’t grenade something is still a mystery to me, but you do not want to stress the system with over pressure.
A word of caution here. Absolutely do not use tech stream to run the pump for more than 10-15 seconds if you think there’s a clog. I did this. The pressure in tech stream jumped past 30 and it raised the truck to the shock travel limit. I’m talking 10-12” between the top of the tire and the fender well. It looked cool and was very stupid. How I didn’t grenade something is still a mystery to me, but you do not want to stress the system with over pressure.
Separate but with the rash of similar issues, I almost wonder if this needs to be a PSA?
Specifically not to ever remove the inline filter for the possibility of introducing foreign contaminants or air? Possibly not to even siphon out fluid from the reservoir? I know we aim for better as enthusiasts but there's certain risks with some procedures.
- Thread starter
- #26
Got it. My pump sounds the same whether it's run in reverse or forward. To me that means there is a clog/s somewhere. Does that sound like a fair assessment?
Removing the pump will have to wait till tomorrow unfortunately
I second this. I followed another posts recommendation and switched to filling through the filter. I used a funnel zip tied to a ladder and a length of 3/8 hose for my subsequent fills. The amount of fluid mix between the old and new is pretty negligible once you do a few bleeds, and there’s much less to worry about. Air in the pump sounds worse than it probably is in the long run
The same thing (pump cavitating and not building pressure; AHC error code C1763) happened to me 2 month ago (July 2021) when I was changing the AHC fluid out on my 2013 LX. I end up taking out the AHC reservoir and pump to inspect and clean the small filters. I had a spare 12VDC battery so I was able to hook it to the AHC pump connector to test normal flow and reverse flow (reverse the polarity). This also allowed me to prime the pump. Make sure you bench test the pump prior to installing it back to make sure that the AHC fluids coming out do not have bubbles (aka cavitating). If bubbles/cavitation are present, you probably reverse installed the pump gear bearings (notch toward the wrong side). It turns out that my inlet filter (very small to find unless you take apart the pump) was partially clogged with small paper/fabric like debris. Once cleared, you need to make sure you install the two small pump gear bearings back properly. There is a little notch on the two pump gear bearings and I believe they have to be pointed toward the inlet side. My AHC pump cavitation issue went away and the pressure was able to build quickly. It took me about two weeks of troubleshooting with Techstream and reassembling the AHC pump twice to figure out that I installed the pump gear bearings in reverse. So take a note of the original position when you disassemble the pump gears/bearings.
There was a lot of research on why/how hydraulic pumps cavitate. I almost gave up and brought a new AHC pump/reservoir ($$$). If you run into frustration, just take a day or two off and think systematically to clear your mind. Once I did, I came to the conclusion that I need to find out what is causing the pump to cavitate. That led me to discover the clog and the reversed installation of my pump gear bearings (during my first disassembly). Hope this helps.
There was a lot of research on why/how hydraulic pumps cavitate. I almost gave up and brought a new AHC pump/reservoir ($$$). If you run into frustration, just take a day or two off and think systematically to clear your mind. Once I did, I came to the conclusion that I need to find out what is causing the pump to cavitate. That led me to discover the clog and the reversed installation of my pump gear bearings (during my first disassembly). Hope this helps.
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Awesome Post! Did you clean the filter with the cue tip without removing it? Just making sure since there was a post earlier where the person tore the filter trying to remove it.
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Yes. Very carefully clean it so you don't damage the filter. I wasn't comfortable removing the filter since it is very easy to damage. Those are not standard size cue tip. The cue tips in the photo are the small ones you find in Japanese stores (or maybe some pharmacy). The heads are about half to 1/3 the size of a regular cue tip.
- Thread starter
- #31
In the process of dropping the pump/reservoir now.
Dumb question... after I've cleaned the inlet and discharge filters and bench tested the pump in my test environment and I know everything is back in working order... do I re-install the pump/reservoir with fluid in the reservoir? Or install it dry and fill it up? I know that sounds like a stupid question but I feel I've already made some rookie mistakes, so...
Dumb question... after I've cleaned the inlet and discharge filters and bench tested the pump in my test environment and I know everything is back in working order... do I re-install the pump/reservoir with fluid in the reservoir? Or install it dry and fill it up? I know that sounds like a stupid question but I feel I've already made some rookie mistakes, so...
As a side note, the AHC pump is a simple and pretty robust design. I think I ran it over and over probably over 100 times during the two week of troubleshooting. Sometimes I ran it for approx 1 minute when I manually connected it to the battery. Then I let it cool down and also so I don't fry my electrical cords to the battery. I thought I was going to damage it but when I took the pump apart, everything looked clean and no signs of damage.
With the AHC pump/reservoir removed from the vehicle, I installed the reservoir dry first. Then fill the reservoir with enough AHC fluid to cover the inlet/suction port. Afterward, connect the discharge port to a drain/collector. Then power the AHC pump manually from the battery to check flow (no bubbles). This also prime the pump. with the remaining fluid in the reservoir(to cover the inlet port), disconnect the discharge port and plug it with a rubber cap. Install AHC pump back on vehicle. Remove discharge port rubber cap and connect hardline.
- Thread starter
- #34
So this is how the pump runs after removing the reservoir and cleaning the pump from the outside with carb cleaner. I have not taken the pump apart yet to clean the filters.
After you clean the filters, install a clear PVC tubing on the discharge port and connect it to a bottle. Submerge the other exit end in the bottle with AHC fluid so no air get sucked back in. Watch the flow and look for bubbles. This will tell you if you are still cavitating.
Here is the link to my AHC pump bench test.
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- Thread starter
- #36
Pretty sure I found my culprit...
I cleaned the pump and it is/was operating as it should. Awesome! So I re-installed the pump/reservoir and began refilling the reservoir, but this time WITH THE FILTER.
Then I noticed this moving through the tube...
So I stopped and pulled the filter in the filler neck. It was filthy with some kind of jelly-like substance. I cleaned the filter (see clean filter pic below) and started refilling the reservoir again. After what was maybe less than a cup of fluid I pulled the filter again (see nasty filter pic).
Poured what was left of the bottle into an empty water bottle.
This was from a brand new sealed AHC bottle purchased from a Toyota dealership.
Not sure where to go from here. The filter in the filler neck seems to be filtering this crap out but I'm not sure if I want to put another bottle of this in my reservoir (right now it's lower than max)
I cleaned the pump and it is/was operating as it should. Awesome! So I re-installed the pump/reservoir and began refilling the reservoir, but this time WITH THE FILTER.
Then I noticed this moving through the tube...
So I stopped and pulled the filter in the filler neck. It was filthy with some kind of jelly-like substance. I cleaned the filter (see clean filter pic below) and started refilling the reservoir again. After what was maybe less than a cup of fluid I pulled the filter again (see nasty filter pic).
Poured what was left of the bottle into an empty water bottle.
This was from a brand new sealed AHC bottle purchased from a Toyota dealership.
Not sure where to go from here. The filter in the filler neck seems to be filtering this crap out but I'm not sure if I want to put another bottle of this in my reservoir (right now it's lower than max)
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OMFG. So sorry you had to go through that. What a waste of time and effort to find Toyota's **** up. Definitely validates the recent reports with the rash of issues, possibly many related to contaminated AHC fluid.
@CHAOTIC
forum.ih8mud.com
@CHAOTIC
New Member Intro - 2013 LX570 - Also an AHC Alert!!!
I just wanted to drop in and introduce myself, as I recently purchased a 90k mile 2013 LX570 in Starfire Pearl White, and have been constantly browsing over the wealth of information that this forum has to offer for a few months now in preparation of that purchase. I'm new to this forum, but not...
forum.ih8mud.com
Yep I remember seeing this post back in July. I brought my AHC fluids back in early June 2021 from my local Toyota dealership and when I poured it through the neck filter, I didn't have the gel looking stuff building up in the filter. They told me it is the last 5 bottles that they have and will need to restock after I purchase them. I think I got lucky and got them before the bad batch got shipped.OMFG. So sorry you had to go through that. What a waste of time and effort to find Toyota's **** up. Definitely validates the recent reports with the rash of issues, possibly many related to contaminated AHC fluid.
@CHAOTIC
New Member Intro - 2013 LX570 - Also an AHC Alert!!!
I just wanted to drop in and introduce myself, as I recently purchased a 90k mile 2013 LX570 in Starfire Pearl White, and have been constantly browsing over the wealth of information that this forum has to offer for a few months now in preparation of that purchase. I'm new to this forum, but not...
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Holy crap. I wonder how many pumps have been trashed by that.
