M-TDI Vanagon Suddenly Blowing Huge Clouds of White smoke

[daltonhawk]

Chris at T3technique got the input shaft here quickly and I finished putting the van back together tonight. Due to USPS issues, I actually got all the DMF/clutch parts before I got all the engine parts. My lifters are still in postal limbo so I ended up getting some from Napa.

Everything went pretty well. My first valve hand lapping experience went well I think. I quickly got a complete scratch pattern on the head and valve bevel and called it good (less than 1 minute per valve.) The valve stem heights ended up very close to the starting heights.

I made a TDC mark on the DMF that's 34 teeth from the factory mark. I read online that it should be 37 teeth but my measurements (dial gauge/water tube) got me to 34. I'm not sure if 37 is wrong, there are manufacturing tolerances that effect it a little or if I just wasn't precise enough.

A few possible clues about the original issue:
-The new timing belt is much tighter than the old one was now. I never noticed the pointer position on the old tensioner but I remember it being looser.
-Cleaning the the cam nose/sprocket with brake fluid got some grime off.
-When I timed the pump the starting lift was only ~0.2mm. I had to turn the pump quite a bit to get it to 1mm which is where it was running well before.

So tonight I started it up for the first time in over 6 months. It took a while to prime but now it runs, but it's loud and barley idles. Lots of diesel knock especially when it almost dies at idle and I touch the pedal to keep it running.

I'm thinking of backing off the pump to maybe 0.75mm to see if it makes a difference. I'm not sure why it would be different now.

[old_man]

[MarkWard]

I recall suggesting you make your own TDC mark while the head was off. Oh well.
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[daltonhawk]

[MarkWard]

All you can do then is trust your mark and move on from there. I don’t know enough about this setup to be of more help. It’s likely the original problem exists still. Getting the head refreshed and the timing correct improved it some.
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[daltonhawk]

Yeah. Also, I put the engine together and set the cam and pump timing while it was on the stand using the mark I made after measuring TDC with the dial gauge.

Now, in the van and using the newly punched dmf mark, I measure the same 0.039” of lift so it seems like all my measurements are reconciled and the problem is elsewhere. It does start now and it wouldn’t start before so it has improved but maybe there were multiple problems as suggested.

[MarkWard]

What about adding a little more lift to the pump? Doing the conversion. .039 x 25.4 = .99

The last mechanical TDI that came to us, had an aftermarket pump without any details for checking pump timing running like arse. It seemed to run best at 1.5 / 25.4 = .059 " You shouldn't hurt anything by trying this.
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[daltonhawk]

Ok, I’ll try moving the pump in both directions to see how it changes and report back.

[old_man]

[MarkWard]

I wouldn't just move the pump, I'd measure what you are doing. Less lift is likely not to help I'd start with increasing the lift. Maybe .050" to start. Sorry, my dial indicator is metric, so I'm calculating the conversion to match your dial indicator readings.
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[daltonhawk]

[daltonhawk]

[?Waldo?]

As others have said, 1.00mm is insufficient plunger lift for virtually all properly built mTDI injection pumps. I would advance from there.

I haven't ever counted the teeth for making a timing mark. I have used the method of running a tube from the #1 cylinder into liquid and watched for the bubble/reversal of the fluid. That method is quite accurate and repeatable.

[daltonhawk]

Well, no clarity yet. It seems to run all right with 0.25mm of lift.

At 1.5mm I got more smoke than fire. It's possible I gave up too soon. To get the dial gauge mounted I have to undo two lines at the pump which introduces air in the system so maybe it would have smoothed out if I let it run longer but it didn't' seem like it.

I should get a new set of lines. With no spare set I'm not brave enough to try bending them to fit the gauge. I can see there's a little arc that was supposed to provide clearance but it's not centered.

[daltonhawk]

I got brave and bent the fuel line a little to allow dial gauge access and tried various settings. It still likes 0.25mm. I drove it a little on my driveway just in 1st gear and I think it seems really similar to when it was running well before, although I haven’t given it much throttle. It holds and idle without smoking.

So, I think the pump might be suspect. I measured the total lift at 3mm again so my measurements keep coming in repeatable.

I bought the van from someone who wasn’t mechanically savvy and had bought it already converted so I don’t know anything about the pump. It came with a large recipient from North Westy that I thought was for the conversion but I talked to them and they just did a new exhaust, work on the carrier bars, a serpentine belt conversion and put in an air to liquid intercooler all back in 2014. The fact that these items weren’t taken care off originally doesn’t give me much confidence in the pump, although after I did some suspension work, it cruised at 70MPH without breaking a sweat and got close to 30Mpg.

North Westy put in a very nice exhaust but hung it from the body and the carrier bars needed some more work since they were in contact with both sides of the rubber on the engine mounts making it pretty loud inside before I modified it yet again. I guess nobody is perfect.

Anyway, about all I know about the pump is that I’ve been told that it looks like an aaz on the outside.

[daltonhawk]

I was just thinking of when I was first getting to know the van and I decided to check the injection timing. First I found that I didn't have a good TDC mark in the correct location (which I recently discovered was due to the pressure plate being installed with missing roll pins and rotated by one screw hole.) Then when I measured to find TDC and checked the lift, it was at 0.25mm. At the time I changed it to 1mm and found surprisingly little difference. I thought it might be slightly quitter. So now I'm back to the original 0.25mm and it's starting to seem like I don't have a correctly built injection pump.

[MarkWard]

You lost me. You said .039” lift and now you are talking .25 mm. Something does not compute.
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[daltonhawk]

Sorry for the confusion.

I tried 1mm(0.039"), 1.5mm and 0.25mm and it seems to run best at 0.25mm which doesn't seem right.

[old_man]

[?Waldo?]

To be clear I wasn't saying it was a bad idea, just that I hadn't personally done it and couldn't confirm or refute the correct #.