Rabbit Diesel 1981 not idling normally

[george_rabbit]

I have this VW Rabbit Diesel LS 81, it runs pretty good, though when driving, it won't go back to normal idling speed. It actually stays in the revs like when it is driving engaged (i.e.: in 4th gear, or any... .). The only way to take it back to normal idling, is pushing the brake pedal having the transmission engaged on 4th., before it stops... then push the clutch pedal so the engine can keep running. I first thought it could be a jammed or dirty accelerator cable, but it works ok, i even soaked it with WD-40, also did the same with the injection pump, with no results.
I wonder if this is a typical problem with the WV Rabbit Diesel's, and if there's any trick to solve this problem. I lowered down the idling speed from the adjusting screw on the injector pump, and works a little better, but still... I know if I keep on playing with the clutch pedal and brake pedal all the time to get the normal idling, I'll finally going to mess up the clutch press, and clutch system itself, rubber joints, etc... and I don't want that!

Thanks for your help!


George

[BlackTieTD]

i sent george over here from the dark side (whoretex) so y'all put on your thinkin caps  :roll:  

welcome to the VW diesel forum george.

[fspGTD]

How is oil consumption on the engine?  If it's got really worn rings, excessive blowby will shoot past the rings, causing an excessive volume of blowby (carrying with it, an excessive volume of oil droplets from the crankcase) to recirculate into the air intake.  The oil actually ignites and runs the motor, potentially leading to a destructive "runaway" condition!  To test if this might be the problem, try removing your blowby recirculation hose.  Rig it up so it blows into a catch-can of some sort, and plug the barb on the intake manifold.  Try running the motor with it like that... if the engine speed now returns to idle no problem, you have found your culprit.

If that's your problem, unfortuntely I don't know of an easy and effective system that completely removes the oil droplets from the blowby vapor.  I have tried a lot of things that don't work completely - they help but not completely effective.  A sure-fire way to fix the problem would be to rebuild the motor to reduce leakage past the cylinder rings.  DieselsRCool up here once had excessive oil in the blowby but his compression numbers were all in order.  He just replaced the oil scraper rings, leaving the other rings in tact, and reported that it reduced the blowby or oil quantity in the blowby.  His motor was I think freshly rebuilt, IE: I wouldn't count on that working unless all your compression numbers test to be good.  But that is another thing you could try that is cheaper than a full-engine rebuild.

There is another potential cause of this problem that I am aware of, but only if you have tweaked your fueling level on your injection pump to the max.  This I think would be really hard to do on a 1.6lNA.

Hope this helps... good luck

[dieseltech]

i had this problem too.  it turned out to be a bolt missing that supports the injection pump to the engine block. its the bolt under the inj, lines on the pump. at certain rpm's  the pump would vibrate and somehow keep the engine reved to about 2000 - 2500 rpm. new bolt and washer. no more "cruise control"