AHC Pump Fun - Disassembly and Clean - Verbose Edition
- Thread starter chalice
- Start date
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bloc
SILVER Star
Great tech! One suggestion though.. please consider posting a dedicated thread titled specifically on the pump operation and images/video, and maybe some of the symptoms from this thread. Also consider just uploading the images here so they are more likely to stay up if imgur or whatever hosting has issues perhaps far in the future.
I know it’s work (trust me) but it makes this great stuff easier to find for people having these issues in the future. Plus others doing similar work and finding similar issues might be more likely to post in that thread vs in this one since it was your troubleshooting. Also can more directly be added to the indexes of tech/how-to/FAQ stuff.
Either way, thanks for posting and following up.
I know it’s work (trust me) but it makes this great stuff easier to find for people having these issues in the future. Plus others doing similar work and finding similar issues might be more likely to post in that thread vs in this one since it was your troubleshooting. Also can more directly be added to the indexes of tech/how-to/FAQ stuff.
Either way, thanks for posting and following up.
- Thread starter
- #24
Yep, I plan on a better thread for all this. I was very verbose here to make sure I didn't skip anything. I also had to do a lot of running around this forum to find data, something I want to prevent others from having to do.
Lots more data to add, as I didn't remove the bumper at all.
The saga continues though:
I'm an hour into a drive down to SD and just got an AHC error on the dash. So put away the champagne for now.
Now I get to sit in traffic and rack my brain haha.
Lots more data to add, as I didn't remove the bumper at all.
The saga continues though:
I'm an hour into a drive down to SD and just got an AHC error on the dash. So put away the champagne for now.
Now I get to sit in traffic and rack my brain haha.
bloc
SILVER Star
Do we want to start calling these pump issues the KDSS lean of AHC?
- Thread starter
- #26
It is pretty easy to drop the pump & assy. You can remove the guard without removing the bumper, but be warned that it is difficult getting the 2 bolts on the outboard side. I'm currently driving without the plastic guard to inspect easily.
How I dropped the pump [or would]:
- Remove spare tire [I didn't, made it hard lol]
- Remove plastic guard
- Get the jack under the pump mount
- Disconnect 12V + Sensor harness AND dismount them from frame clips [2x clips at the connector and 1x strap clip half way to the pump assy]. Be patient here, clips are stiff and full of road grime. This is further aft and faces the spare tire, you do not need to disconnect at the pump.
- Remove filler neck bolt, disconnect the vent hose from the top side of the filler neck mount. The smaller OD vent hose goes down to the motor and will stay on assy.
- The pump & assy is mounted to the frame via 3x12mm bolts, two are easy. One is a pain as the hardline to the pump is in the way. Use a swivel or ratcheting crescent.
- Once bolts are loose and everything else is ready, use a 10mm flare to loosen the hardline. If you emptied the reservoir, go ahead and pull the hardline out of the way. If you didn't empty the reservoir, have an oil tray and your finger ready to cover the port.
- The hardline needs to be pulled outboard while you lower the pump, use the jack or another set of hands. At the same time the filler neck can swivel and make sure you pull the sensor & 12v harness over the frame so it doesn't snag.
- And you're done!
Breaking down the pump takes 10 minutes and is straight forward. Granted, I have some experience in vacuum pumps and building engines. Once you get inside though, I spent probably 30 minutes figuring it out, inspecting, and trying to find the filters that were right in front of me hah.
- Thread starter
- #27
The one question I have on the whole pump assy is the pump attenuator. There is a very large hex in the bottom of the pump head case, and from my inspection I figured that was for the high pressure gas "thing". Love the tech notes on the attenuator, but it's kinda a mystery box on longevity and how to test it...unless there are more notes in the manual.
Also, @TeCKis300 I thought there weren't any pump head breakdown diagrams! But, it's nice to see my analysis of the flow/etc. was correct while cleaning.
Short drives I'm not getting any errors and it seems to function on the freeway as intended. After an hour of going above/below 60mph due to traffic I had AHC errors pop up twice. I'm thinking the 5th accumulator needs to be bled again, if not all the corners.
Also, @TeCKis300 I thought there weren't any pump head breakdown diagrams! But, it's nice to see my analysis of the flow/etc. was correct while cleaning.
Short drives I'm not getting any errors and it seems to function on the freeway as intended. After an hour of going above/below 60mph due to traffic I had AHC errors pop up twice. I'm thinking the 5th accumulator needs to be bled again, if not all the corners.
- Thread starter
- #28
@radman do you have a particular way/sequence of bleeding the 5th accumulator? Thought I read you're an avid fan somewhere. I've been starting in Normal height, opening bleeder until solid clean stream of fluid comes out, and then closing. Start the truck back up and go to High mode.
Very cool. There weren't any breakdown diagrams in the regular FSM. That's when I went digging for more and found the detail AHC documentation I posted in the other thread.
Here's the link again - http://gershon.ucoz.com/TOYOTA/landcruiser200/AHCS/m_ch_0114.pdf
Do you know what AHC error you're getting on the freeway? The lowering function at freeway speeds (~62mph) is likely using the 5th accumulator in some manner to support this function. You might have licked the priming function and just need to bleed the accumulator to fix a slightly separate issue.
- Thread starter
- #30
Unfortunately I didn't have my laptop with me when I got the errors.
And yep, that's my assumption on the 5th being used on fwy. I did one full bleed [all 5] post pump install, but wouldn't be surprised if I need to again.
- Thread starter
- #31
Couple more notes so I don't forget:
- I had ZERO AHC problems prior to a flush from Normal height. Front struts had been replaced, and I have bled the system previously without issue from Low height.
- Easy access was on often and we routinely go to L or H modes.
- The front driver corner is ~.5 inch lower than front pass corner.
- This occurred after the front struts were replaced, I was bleeding to prep for leveling and an upcoming Tahoe trip. Glad I gave myself an extra week!
- The passenger side looks perfect. I need to get the driver side to match.
- Reviewing the AHC Suspension manual, this kinda makes sense as the front height control assy and valving is on the passenger side?
- Do not pass go. Do not collect 200 dollars. Do not remove the filter when filling the AHC reservoir.
- I think we might need to find a go-to transfer pump and assorted fittings/tubing to facilitate easy, fast, and CLEAN filling of the res.
- Source high quality tubing without plasticizer?
- I always kept a dedicated AHC fluid pump and hose in a sealed bag - I also ran a pump of fluid through the line prior to filling the res.
- The vent on the reservoir is for releasing pressure, I couldn't get air coming in the line to break suction.
- Doing a high volume bleed/flush this might pose a problem as my pump started to cavitate under suction.
- This same suction might have been the start of my problem. Suction causing debris/dust in the res to head to the pump head inlet filter.
- Something that wouldn't happen without suction in res?
- The reservoir is going to get debris/dust in it no matter what due to design, the filler neck cap isn't a crazy tight or solid seal. Behind the rear tires is a very dusty/dirty environment on and off road.
- How do we find out the service life of the attenuator, or how do we test it?
- Do our brethern in EMEA with AHC equipped LC200s have experience in this realm?
- More dust, more dune romping, and more AHC?
Hit that 5th one first. It’s driver’s side (midline of the truck). It won’t refill until you initiate a lift from N to
Hi.
I go ahead and start the rig and let it do it’s thing after every bleeder (out of paranoia). There’s a summary in the link below.
Post in thread 'The Big Bad Rad Dad LX Build'
Builds - The Big Bad Rad Dad LX Build - https://forum.ih8mud.com/threads/the-big-bad-rad-dad-lx-build.1208847/post-13083196
- Thread starter
- #33
Yeah I hit the 5th first each time, can get to all 3 heatshield bolts without looking now hah. Wanted to confirm that it refills only when you go from N to H.
Also agree that restarting after every bleeder should be SOP. Thanks for the reply!
Very good points! Especially concerning filling tubes and dust ingress. Going to be extra paranoid on my next flush (as if I wasn't already). Now trying to decide if I want to make a pump tear down part of my 120K service too. Can't help but think there may be a "little" gunk in there.
Great notes. I think this point deserves extra highlighting.
I not quite following on the suction points you're describing? Are you describing flushing with the reservoir cap on creating a vacuum?
He is referring to the reservoir filter. It has a check valve allowing egress, not ingress (I did not realize this). After a bleed, it can create a lot of negative pressure pulling in the new fluid.
- Thread starter
- #37
Yes, bled from Normal height on all corners and filled the reservoir all the way to the filler neck. When the pump kicked on it took a lot of fluid from the reservoir without make up air, creating the suction.
Cracking open the cap gave a very audible suction relief. Pump went from high pitched whine back to normal operating sound.
- Thread starter
- #38
I'm not sure I'd be paranoid, but more confident in what to do if problems arise down the road.
I also am thinking more and more that this could have been avoided if the reservoir wasn't under suction. Just unplug the vent line, which is what I did when priming and bleeding post pump reinstall.
Updated thread title, I'll definitely create a new thread once I'm more confident in total performance. But, I do recommend NOT removing the filter while filling, and only doing one corner at a time if you bleed from Normal height or the 5th.
@chalice Sounds like you bled all four at the same time? Is this the case? If so, I think that's the main mistake many make causing this behavior. Bleeding all four corners w/o refilling between bleeds drops the level so far it increases the odds of pulling in bottom sediment and clogging the filter.
Just curious.
Just curious.
Stumbled on this thread that is a few years old. It has pictures of the filters removed from the pump housing. Sounds like the OP destroyed the filter trying to remove. So i guess if you don't have replacements, i wouldn't try removing.
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LX570 AHC pump filter
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