1.6TD jerks and shudders at certain RPM / throttle

[anzee]

Hello, new guy on this forum.

My 1.6TD in my VW T3 doka (engine is from golf 2 i assume) started behaving a bit strange.
During easy acceleration or steady cruising, around 2000rpm and ~10% throttle the engine starts jerking. If I accelerate at that point, the engine stabilizes and accelerates normally. Engine also starts without problems and it also gives out its normal power during full load.

I tried to manually operate the throttle and slowly bring up the rpms - at certain rpms you can feel a "click" of some sort and the engine hesitates and jerks. I can make a video if that would be any help.

I am guessing there should be something wrong with the throttle / governor combo, or am I seeing it false?

regards,
Anze

[ORCoaster]

Well, that is an odd one.  Not sure what to suggest here. If it does it sitting still I might be inclined to think something with the governor was the cause.

[fatmobile]

Check the injection pump mounting bolts.
 Also the bolts holding the bracket to the block.
Or maybe the governor mod.

[anzee]

Hey!


I made a video of the problem... you can see it clearly at 0:40 - 0:48 and at 1:07. (sadly i cannot post youtube link, if anyone is interested i can send it via pm)


I checked the bolts of the bracket and found something funny.
Should here be two bolts in the bracket? I have only right one, it was a bit loose..


I unscrewed it and examined. 10,8, one large shim which is a bit bent and a bushing of some sort.


What do you think about this?

[ORCoaster]

I think you just found your problem.  Someone probably broke the other bolt off in the block.  Pull the pump off and tap it out and put another proper bolt and washer in there.  I bet your problem goes bye-bye.


Oh as for the bolt you have I am willing to bet it is too long and they put the bushing on to keep it from going too far into the block and breaking something. Get a shorter one, make that two when you get to the hardware store. 
 

[fatmobile]

 Yep, called that one.
 If it was a Rabbit you'd also have felt the peddle vibrate.

 Yep that bolt is too long.
 Doesn't look 8M1.25/metric either.
 You might need to do some helicoil stuff too.
 When you put the bolts in use blue locktite.
I've had them vibrate out before.

[anzee]

This really was the problem! Thanks everyone for help!

It looks like the left bolt was broken, but luckily the tread was just filled with debris. I cleaned it out with cotton buds and brake cleaner. Got two shorter screws, bolted them right in with loctite and yeah, it runs smoothly now!

[scrounger]

Good simple repair. I was thinking that maybe the cam belt tensioner was loose but this is surely better.