Attempted pump repair and rebuild - page 1 - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.
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Attempted pump repair and rebuild by zuhandenheit on 05 Feb, 2018 22:13
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I'm going to attempt to fix the AAZ pump that broke last year. I don't want to get my hopes up, but I don't have much to lose. As I described elsewhere, after a partial reseal of the pump, the o-ring for the idle control lever was giving me trouble. I don't remember clearly what happened: I think I found that it was leaking and suspected that I had used the incorrect seal, or maybe the o-ring wasn't seated properly. In the course of my attempts to fix it without pulling the pump again, which involved a lot of fussing with the rod to which it attaches, a spring came loose inside the pump and wreaked havoc.
I didn't know there was a problem until I started the motor, which was blowing white smoke and making terrible, self-destructing metal noises.
I figured that was the end of the pump, and disassembled it just to see what had happened. I found a broken spring, coffee ground-like rubber bits, and a missing tooth on the governor.
I wasn't careful about disassembly, because I was really just curious and didn't plan to attempt a repair. But now I'd decided to at least take a closer look and see what exactly is damaged, and if possible to attempt to fix the pump.
I'm interested in the inner workings of the pump anyway, so it won't be a waste of time.
I'll document the process here.
First question: I'm thinking about how I can properly clean the parts. Would it make sense to get an ultrasound cleaner?
Is there a solution that I could use to soak parts to remove external rust that wouldn't etch or otherwise damage the internal surfaces? For instance, I was just considering the delivery valves (pictures forthcoming). If I weren't concerned about the finish on the internals, I'd put them in either a phosphoric acid or vinegar solution to dissolve the rust. But I am fairly certain that would be a bad idea, given that I don't want to etch the machined internal surfaces. -
#1 by zuhandenheit on 05 Feb, 2018 22:27
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Here's where I am currently:
See the rubber bits?
Up to this point, disassembly was pretty straightforward. Everything has been in baggies for over a year, when I last touched it. I'll take it the rest of the way apart tonight. -
#2 by zuhandenheit on 05 Feb, 2018 23:10
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Oh, sorry about the huge pictures! I'll fix it soon.
I've got the actuator pin loose, and am assuming that the roller carrier etc will now come out . . . ? -
#3 by zuhandenheit on 05 Feb, 2018 23:31
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Okay -- I got it apart -- never mind the request for help. I'll post pictures soon.
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#4 by zuhandenheit on 06 Feb, 2018 16:05
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I've got a lot of pictures, and it's much easier to just share an album than to embed everything here: https://imgur.com/a/HU2mH
You'll see there's a mess of rubber bits in everything. I have not found any damage aside from the missing tooth on the governor gear. Aside from the rubber, the pump seems very clean. I of course don't know what I'm doing, but I haven't seen any indications of oxidation or pitted surfaces. I'm thinking I'll clean everything, take apart my 1.6 pump for the gear, and then reassemble using Vaseline.
I have two big questions: I've got a reseal kit and will replace all the seals and copper washers etc. I understand that a 'rebuild' is more involve, and should involve calibration and so on. I of course don't have access to the equipment needed for calibration. So, aside from cleaning and resealing, is there anything I should do while I've got this apart? I think the input shaft bushing is in good condition . . .
Second question: As I said above, I took this pump apart out of curiosity without the goal of attempting a repair. Once I saw, after removing the head, the damaged gear, and spring and rubber bits, I kept going just to see what else what damaged but not imagining I'd attempt a repair. Thus, I didn't document the process or mark anything, but I also didn't mess with anything that I knew needed to be replaced in some specific orientation -- however, I learned later that I overlooked something in this regard.
I have not touched any of the adjustment screws on the head, and I'm not worried about the throttle lever (I have dealt with this before and didn't have much trouble getting the position right). And it may still be marked from before. I know how to orient the cam-plate.
But doesn't the 'governor shaft' (or something) in the head of the pump need to be oriented a certain way (which I should have marked)? If so, how much of a concern is this and what can I do?
I did at least try to keep the parts together such that various wear surfaces (like on the rollers) would all be positioned as they were originally.
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As for cleaning, my plan is to maybe use an ultrasound machine, and at least blast everything with WD40 and then compressed air. It will be a lot of trouble to be sure I've cleaned out all of the rubber.
By the way, if anyone happens to have a replacement for this damaged gear, I would prefer to buy a replacement than to tear down my 1.6 pump, just because the latter was working and I hate to ruin working parts, even if they're not worth much, or of any use to me! -
#5 by libbydiesel on 06 Feb, 2018 19:05
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That looks fairly easy to set right. Was the idle spring the culprit. What happened to the rest of it?
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#6 by ORCoaster on 06 Feb, 2018 21:57
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I didn't see the small spacer that goes in front of the fueling piston. It might still be stuck in place. That little bugger needs to be smeared with Vaseline to keep it in place as you insert the whole head and piston assembly. Those springs get the sticky stuff too.
Yeah lots of rubber bits to get out of there. You have a kit so you have replacements.
If you just put things back together with new seals and don't mess with any adjustments you might be fine. The one I would worry about is the pressure relief valve up front. Don't take it apart from the piece that keeps it in the body of the pump. Position on it is what gives you the initial internal pressure and what makes the advance do its thing.
If you follow a pictorial or U tube video of the pump assembly you should be fine. I think there might be something in the sticky section on pump assembly. Might be that the pictures are now messed up it if it was done with Photo Bucket initially.
If you didn't count the number of turns the governor shaft was held in with you might find that it will rev to high or low upon assembly. An easy fix once assembled. You just release the locknut and turn more or less depending what you need to get it to limit out at 5,000 or so. -
#7 by zuhandenheit on 07 Feb, 2018 04:05
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Thanks a lot for the replies.
Well, it was either the idle spring, or another small bit that I found which appears to be the carrier for the spring -- the hook on the lever. So, minimally I'll need to replace the spring and the lever. The 1.6 pump would most likely not have these parts, since it doesn't have the cold start mechanism for raising the idle, so the design will be different. I haven't looked at that pump in awhile and don't recall whether it has anything like this lever.
As for the remains of the spring -- I removed most of it when I first took apart the pump last year. The little bits that you see here are what I didn't get the first time.
ORCoaster - I think I remember that washer. Iirc, I placed it somewhere so that I could keep the original orientation (I stuck it to something). I don't know how important it is to keep wear surfaces together, so I'm trying to be careful about this sort of thing.
I removed the pressure relief valve but didn't take it apart.
One of my concerns is getting the rubber out of the high pressure head (or whatever it's called). Between the inlet and the delivery valves, there are lots of bits, and it appears that no further disassembly is possible. Can I just blow through the holes on both sides (into the ports for the valves and from the other side, into the inlet)?
I would have thoroughly cleaned the exterior of the pump if I'd been planning this repair. The aluminum will clean up nicely enough with degreaser. It would be nice to also remove oxidation from the iron and steel parts, but I'm not sure how to best go about this. As I said before, if I weren't concerned about the inner surfaces, I would for instance toss the valves into a phos acid solution -- but won't, because I don't want to etch the inside. Any suggestions for things like this? -
#8 by zuhandenheit on 07 Feb, 2018 04:06
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Oh, and I meant to ask: The first picture of my album shows the cold start piston still in the bore. I don't know how to remove it. Suggestions?
Thanks again for the help. Even with the guides I've found online, there's no way I'd attempt this without you guys looking over my shoulder! -
#9 by sgnimj96 on 07 Feb, 2018 05:37
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the big pin the goes from the roller assembly into the timer piston needs to be slid back out of the timer piston. I may be stiff with crud and corrosion, but all that stuff is supposed to move - that's how the timing advance works.
https://youtu.be/pLSefeFnF4w?t=1030
The timer piston gets it the worst with the crud and rust, since it's at the bottom of the pump. -
#10 by ORCoaster on 07 Feb, 2018 22:50
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Not sure the link will help all that much. You can't see what the guy is doing with his big meaty hands between the camera and the little clips and pins he is removing. Watch it a few times and compare what it looks like before he starts taking stuff out and then when he is done. There are actions he is doing that are not shown but I think you can figure it out with a few views and having a pump handy to spot on.
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#11 by zuhandenheit on 27 Feb, 2018 05:54
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Thanks for all the help. I had to take a break, but I'll soon be getting back to work on this and will post updates as I go along.
I'm thinking I'll tear down my old 1.6D pump for replacement parts. I'm not sure how I'll replace the spring that cause the damaged, however! I'd rather not sacrifice another pump just for the spring, but we'll see. -
#12 by sgnimj96 on 27 Feb, 2018 14:30
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#13 by zuhandenheit on 08 Mar, 2018 09:47
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That's awesome -- thanks!
I've been running a pump that I bought from a forum member recently. It was rebuilt very recently, but from the time I got my hands on it, I had a bad feeling. (I posted about this in another thread.) And I got maybe 300 miles out of it before it began to leak like hell from the input shaft. I pulled the pump and found that there is a ton of play in the shaft. I bet it was run with the timing belt too tight and began leaking from the input shaft and was rebuilt for that reason, and then the rebuilder neglected to replace the bushing and just resealed it. So of course it very quickly blew the seal.
I bought that core -- I can use it for this ***ty rebuilt pump to fix the input shaft (hopefully, or in any case it's worth a risk).
Meanwhile, I bought this:
https://www.ebay.com/itm/vw-aaz-Giles-tuned-diesel-injector-pump-/152912362718?item=152912362718&ViewItem=&nma=true&si=DfNuvnASh3e4%252FxYTJWvDF0SMaD8%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557
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#14 by libbydiesel on 08 Mar, 2018 10:47
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That is the later AAZ pump style that uses the hub/sprocket setup and so has the larger hole in the pump bracket. Do you currently have that style of pump? If not then you will also need the later AAZ pump bracket and when installing it, will need to adjust the timing belt tracking.