Vibration / Noise at low RPM

[ajd]

Alright, problem solved. Bringing this thread back just to close the book on it.

I ended up getting the time to do a big rebuild (Is been on my list, not for the vibration but for cracked head and leaking gasket). As one would expect the van runs way better all round. Hard to pin point what was the cause of the vibration because I rebuilt so much, but I'm pretty sure it was my injection timing. After the job, the engine was still pretty shaky at low rpm, then I noticed my injection pump was set to full advance! My pump has always been rotated over so much that it was crushing my upper rad hose, and I never knew why. After some research and reading old threads (thanks delica.ca!) I rotated the pump back to about 3/4 of the way to full advance. The vibration is at a much more comforting level now, and i'll probably get a more efficient burn on the highway too, although I have not tested.

Here is what I rebuilt:
New head + gasket
Front seals
cleaned manifolds
rebuilt turbo
new alternator
new timing system (including balance belt which on tear-down I found to be broken! aaah)
new accessory belts

[Growlerbearnz]

Yikes! Glad you found the ludicrous timing before it wrecked your new head and gasket!

Stock timing is about halfway in the range, so you may still be a little advanced. For the record mine ended up about 3/4 advanced, set by trial and error- (listening to the rattle, watching the exhaust temperature, feeling for power loss at high boost when the engine's hot).

Setting the timing to factory requires a dial gauge and special adapter though, which is a pain, and advancing it to get more power safely is best done on a dyno.

[ajd]

Good to know, thanks. I tried a few different settings, but I only listened to the idle and it seemed best at about 3/4. I'll continue to test and take some notes. But for now it's time to do some driving!