Diesel Injection Pump Timing –Chapter 3

[stuzbot]

Wherein our humble author actually starts to get somewhere.

Those of you who followed my thrilling adventures in the hit threads Sigh! –Another Day of Frustration and Help With Using Pump Timing Tool? will know that my "I think I'll just go out and set the pump timing this afternoon" mission has turned into a right bloody saga, thanks to poorly manufactured tools, badly adjusted Cold Start Lever and an original pump lift setting so out of spec I was convinced I was doing something wrong to get such wacky readings.

Anyway, I left you on the edge of your seats at the end of the last thread, where I'd just loosened off the Cold Start Lever, adjusted the pump to spec and actually managed to get the engine to start, albeit for only a few seconds as I soon found out I'd knackered my injector Leak-Off Pipes, with all my thrashing about in the engine bay.

So, more delays and more thumb-twiddling, while I ordered some new Leak-Off tubing and waited for it to arrive.

It did so today and I *FINALLY!* got to run the engine and go for a short drive. What a difference. For the first time since I got the van at the end of last year, I actually got to properly enjoy driving it today, without the sound of those rattling injectors setting my teeth on end. It just makes such a difference having the van sound 'normal' and not like someone's put a bag of spanners in a tumble dryer.

I am officially "well chuffed"!

Of course, things are never completely straightforward with me and this van. As I half suspected, having previously had the pump set so far advanced, the idle is now a tad too low, with the pump retarded back to its normal lift setting. So, the first couple of times I started the engine, it died when I lifted my foot off the pedal.

"A quick twiddle of the Idle Setting Screw" I thought "and we'll be away"

But, as per usual, it wasn't so straightforward. Like the Cold Start Lever, the Idle Adjustment Screw is hidden down the blind side of the pump next to the engine and that valve thingy which sits on top of the pump [and whose name has completely escaped me at the minute!] is sitting right above it, so I can't get a spanner or screwdriver in there.

In the end I just decided to make a bit of a 'ghetto' solution for now, as I was itching to get the van out on the road and see how it ran with the new pump timing. So I loosened off the lever at the pump end and moved the wee section that connects to the throttle cable forward a bit, to give me a few more revs at idle. Not ideal as the section I moved has a hollow in the bottom which sits on top of a hump in the plate underneath. So, obviously the adjustment is not meant to be made here. But it'll do until I work out a way of trying to get in at the Idle Adjustment Screw without having to dismantle anything else.

Im also considering the fact that the choppy idling might have been caused by a bit of air in the system, after my working on the pump. So I'll set things back as they were before I start it next, now that I've been for a drive and purged the air in the system. That'll let me see if the idle really does need adjusting.

By the way. Typically, the screw for limiting the Max revs is beautifully out in the open on the clear side of the pump and couldn't be easier to get at. But you can guarantee if that had been the one I needed to adjust, it would have been hidden away like the other one.

Oh well. At least I'm getting there slowly but surely! :)
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Click to view image
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1992 VW LT35 2,4D [SOLD]
1993 VW LT35 2,4D [SOLD]
1992 VW T3 1,6TD Syncro [SOLD]
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[zuhandenheit]

I'm having trouble telling from your picture, but it looks like you're pointing to the screw that controls the lower limit of the throttle (opposite the max screw). Unless your pump is very different from the one's I've seen, that's NOT where you adjust idle! There's a lever on the back side of the pump, which would be connected to your cold start, if equipped. There are two screws-- one on each side. IIRC, one sets the idle with the cold start pulled, and the other without it.

It should be much easier to adjust these screws than the throttle stop screw you were, I think, trying to adjust!

Also, if you hooked your cold start back up, you could pull it to give you more RPMS at idle while you sort out the problem.

I bought a very lightly used Giles performance pump, which ran great except with a strangely low idle. Until I got around to making the necessary adjustments, I just pulled the cold start to raise the RPMS.

Anyway it's good to hear it's running better!

[?Waldo?]

After you have rotated the pump, you need to loosen the injector line unions at the pump and then re-tighten. If you don't then the added stress twisting on the lines from rotating the pump will cause them to crack and fail. It also looks like your metal lines are all bent to hell and missing the anti-vibration clamp. Without it, the lines will vibrate, work harden, and crack at the unions. I would recommend getting a new set of lines with the clamp and keeping your current lines as backups.

https://www.vw-t3-bus-shop.de/en/injection-line-kit-td

[?Waldo?]

[zuhandenheit]

Thanks for clarifying. I wasn't sure about 1.6td pumps and did an image search, which showed that at least some have the mechanism.

Anyway, sorry stuzbot for the at least largely unhelpful response!

[ZsZ]

You can reach the idle stop screw if you remove the out banjo bolt and move the return line
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Zoltan
1.9 MTdi 2wd Multivan (ex Caravelle)
Van since 2006, engine since 2008

[ALIKA T3]

Most likely your idle settings have not changed unless the screw came loose.

What I usually do after I re seal a pump and want to get the idle neat, is back off the idle screw, remove the accelerator lever (10mm wrench), start the van and set the accelerator shaft with your fingers where idle sounds good. Drop the lever onto the shaft where the cable is happy with tension. Stop the engine,mark the position and reassemble the spring for the lever. Pre tension it, use an electric wire to pull it tight and clip it in place after you have tightened the M6 nut.

No fooling around this way, then bring the idle screw in contact with the accelerator lever. Done
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Silicone Steering Boots and 930 Cv boots for sale in the classifieds.
Syncro transmission upgrade parts in the Classifieds.
Subaru EJ22+UN1 5 speed transmission
http://www.thesamba.com/vw/forum/viewtopic.php?t=416343
Syncro http://www.thesamba.com/vw/forum/viewtopic.php?t=4...num+gadget

[zuhandenheit]

On a few of my pumps, those accel lever stop screws were stuck. One wouldn't break loose no matter what I tried, and I resolved to use vice grips on the end (destroying the screw). But if it were stuck and not too rusty, I'd try screwing on another nut -- after backing off the existing one.

I'm thinking if you could get a second nut on the screw, tightened up against the existing nut (after it's been backed off), that could allow you to make adjustments using a wrench (ratcheting, ideally). Would it then be possible to get to it more easily and without removing anything?

[stuzbot]

[stuzbot]

Righty-Ho...

I took the van out on the weekly shopping mission today and ran into a bit of a snag.

Previously, when the pump timing was advanced to 1,6mm, the van would start first turn of the key when cold. But if I went somewhere and parked up for about half an hour [ie. to do some shopping] and came back, the van would be slightly less reluctant to start –sometimes needing to turn over 3 or 4 times before the engine caught. I didn't worry about it too much as it still started fairly easily, just not "on the button" as it did when cold.

Well, today when I got back in after doing the shopping [so 30 - 40 mins later] and tried to start, the van didn't seem to want to start at all. It was turning over OK on the starter, but not even sounding like it was trying to catch at all –even when I floored the accelerator [mindful of the fact the idle setting might still be too low].

In the end, after trying unsuccessfully to start about 4 or 5 times and, on a whim, I pulled the cold start lever and tried again and it roared into action first turn of the key, with a bit of a 'thump'

So, questions for you all:

1: Reasons for reluctance to start when warm? [obviously this is not a new thing as there was a hint of it before. But, on today's evidence, it's got a lot worse since correcting the pump timing]

2: Why does the engine start easily when cold but [apparently] needs the Cold Start Lever pulling, to start when hot? [That's just being contrary, if you ask me!]

Any suggestions?
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*****************************
Click to view image
*****************************
1992 VW LT35 2,4D [SOLD]
1993 VW LT35 2,4D [SOLD]
1992 VW T3 1,6TD Syncro [SOLD]
*****************************

[?Waldo?]

It could be an issue with the pump itself, stop solenoid, temp sensor for the glow plugs, the glow plug relay, the glow plugs, the starter, the battery, battery pos or ground cables, or compression.

It could certainly be an internal issue with the injection pump. I can think of more than one scenario where an internal issue with the pump would account for all of the issues (lots of diesel clack, high timing spec, hard hot starts, etc...). That's the worst case scenario so I'd make sure everything else is right before going there.

It is most likely not an issue with the glow plug system because if everything else is up to snuff then the glow plugs are not even needed when warm/hot.

Fast cranking is ALWAYS needed for easy starts hot or cold. The starter should whirrrrr. If it chug chug chugs, the cranking speed is too slow. The main contributors to slow cranking are the starter, battery, or cables.

I did not experience it myself but saw someone post how their warm/hot start issues were caused by a faulty stop solenoid that would work fine when cold.

Although tough starts are often blamed on poor compression, I haven't really found that to be the case. If everything else is up to snuff, even with compression below spec then engines will start easily unless the compression is really, really bad.

[stuzbot]

[?Waldo?]

Your RPM values all seem to have an extra zero. The big numbers on the gauge are thousands. It should idle ~800. If it idles low, then adjust the idle screw. Take the fuel lines off if you have trouble accessing the idle adjustment (put new ones on afterward...).

A little constant tension on the cold start lever is, IMO, a bad idea. Warning: overly complicated explanation follows. The cold start lever rotates a little camplate. That camplate pushes against a pin that is pressed into the end of the aluminum dynamic advance piston. That piston moves due to changes in pump internal pressure (which goes up with increased rpms). When the rpms come down, the dynamic advance piston goes back to stop either on the cold start pin or on that end of the plunger if the cold start is not rotated. Rotating the cold start only partially and running like that will result on the piston returning to hit the pin on the angled ramp of the cold start cam. That pounding on the side of the pin could loosen the pin and even cause it to fall out. That pin falling out of the piston is not common but also not unheard of. When it falls out, it can cause damage that will destroy the pump and even make it so it is not rebuildable.

[stuzbot]