Blowby and high revving! Help!

[jtanguay]

that looks like just a worn injector...  my car used to do that until hot... but then i got smog injectors and now all i see is black smoke, with a hint of blue-ish grey due to a possibly dying motor... oh well!

mess around with the timing though.  try 0.95mm and 1.05mm it can't hurt.



here's the "run away" smoke, not easy taking this pic with my foot on the pedal.



here's more idle smoke:



there i fixed that up for you!

[Doug]

How many km/miles have you got on the motor?

[vegfuel]

She's got 220,065 miles! Yeah she's a little worn out, but I was hoping to get another 80,000 if I did a rebuild. I guess I got suckered in to this car, for $400 you can't expect a much. I was just needed a vehicle for my high school biodiesel project.

[dieselsnowmobile]

I have 235,000 on my Rabbit engine and it still runs good.  Engine is practically untouch except for one head gasket and the fuel pump.  You should still have some pretty good life life in that engine if it was reasonably taken care of.  I would think you should be able to get atleast 80,000 before a rebuild.  Looking at the smoke, I still think your problem is with your timing.  That is the same smoke I had when my timing was retarded.  Read up on hill billy timing to advance your time.  Rotate the IP towards the head about 1/16 of an inch, and it should stop smoking.  Or do it the professional way like jtanguay said.

$400 is not too bad of a price.  Does not look like it has much rust on it.  It seems like whenever I get a car, it needs atleast a couple hundred dollars put in it.

[vegfuel]

Yeah, they outside is pretty nice. It's the inside that kinda bad. But who cares!

So you are saying to advance the timing? I could try that.

As for the "over revving" problem, I have found out something else, I know this is getting to be ridiculous but this could mean something:

What is the lever right under the throttle lever on the IP? When pressing on the throttle, THIS lever is not coming back!! It has to be pressed back and it feels like it's gummed up.

[jtanguay]

well Dr. Diesel just acquired a new, very cool toy!  damn!  if you could time your motor with that, i have no doubt that the smoke would go away.

because i do honestly believe that you have worn injector(s).  now if you have one really bad one, and 3 decent ones, that one injector will need to be changed.

come to think about it... that device could actually detect when an injector fires, and allow you to detect an injector that is firing at improper intervals.  SICK!  but then again... if you put a brand new one, you throw the rest out of sync.   If all of your injectors are worn evenly (rarely happens) then you can just increase timing to compensate.  the downside to this, is that if you have a leaky injector, you will be in for some severe damage (my pistons started melting at the edges... mind you i didnt really know much about egt at the time, and would be smoking everyone out  :lol:  engine still runs half decent though!)

IMO, get your injectors done, time it properly, and be happy.  if you run veg, i think people recommend increasing the timing, as the increased viscosity of the fuel will slow down injection time, so you compensate by increasing the start of injection.  there is even a place that sells special veg injectors (bigger nozzle to compensate for higher viscosity)

now if the car was spewing out black smoke (at idle) then you have compression issues.  we don't see that, so this car should easily do another 80'000 with you keeping the oil topped up.  I have personally seen a toyota truck with around 30-50 psi one one cyl, 100 on the next.. 140 on the next, and the last one had 300 or so.  the engine REALLY wanted to start! nice big puffs of black smoke out the tailpipe.  eventually it did run, at around 1500-1800 rpm.  bucked really bad.  but at that point, the motor is pretty much useless.  turns out that the po ran it too hard, and the exhaust manifold runs from front to back, and so the rear cyl got the heat from all 4 cyls and got cooked real nice.  :lol:

[dieselsnowmobile]

vegfuel - It just occured to me that your throttle might be sticking with the springs hanging it up.  I got my rebuilt pump put on and a few says later, it would not idle down very well.  I then realized that the actual throttle lever on the pump took a second to get to the idle position.  The new paint on the springs were hanging it up.  

Solution - hose down the throttle springs with WD-40.  It solved the problem and has not happened since.

[vegfuel]

dieselsnowmobile,

I have already tried oiling the springs on the throttle lever, there is vertually no resistance. I'm just wondering if it might be the governor spring inside the pump connected to the throttle shaft.

Another thing, you said you have a Rabbit diesel engine like mine, is there a lever located right beneath the throttle lever? I have this lever and it is connected to a spring as well but it is as sticky ever.

[jtanguay]

dieselsnowmobile,

I have already tried oiling the springs on the throttle lever, there is vertually no resistance. I'm just wondering if it might be the governor spring inside the pump connected to the throttle shaft.

Another thing, you said you have a Rabbit diesel engine like mine, is there a lever located right beneath the throttle lever? I have this lever and it is connected to a spring as well but it is as sticky ever.

just try and spray some wd-40 on it.  just make sure to wipe up the excess when it's done.  can't hurt.  and maybe it will fix the problem.

maybe it is the accelerator cable itself??? i've had a golf gasser that had a really stiff one...  it wouldn't hang though...

[dieselsnowmobile]

Here is a picture of my newly rebuilt Rabbit pump.  I think that the lever you are talking about is the lever underneath the throttle lever that is against the high RPM limitor block but below the high RPM limitor bolt in this picture.  Unfortunately, I have no idea what that lever does nor if it suppose to be sticky.  The problem I had was when they rebuilt the pump, they hosed everything down with paint which added friction to the spring and eventually made the throttle hang up.  I also remember that on my old Rabbit, the throttle would sometimes take awhile to idle and I did the same thing there too.  Sorry I am not much help as to what that lever does, I am sure someone might know or you could read Bosch Training Manual on the pump and figure it out.

[rabbit_diesel]

is there a lever located right beneath the throttle lever? I have this lever and it is connected to a spring as well but it is as sticky ever.

Yes, that there lever is called the cold start lever (if I'm correct).  It increases fuel to the injectors for easier starting.  I don't really know if that can cause reving or not.  But, when I pull it on my Jetta, it seems that it just fires harder :roll: .

[saurkraut]

Geeze, some times this forum is a font, over flowing with miss information.

The cold start lever is on the back of the pump.

It is nowhere near the throttle lever.  

It has no effect on the throttle lever.

Its is hooked up to a solid wire cable that is attached to the cold start nob in the dash board.

When you pull out the knob, its advances the timing at idle rpm (I don't remember the RPM, but it pritty low).

It does not add fuel.

Above idle, it is disabled.

There is no detriment to driving around with the cold start activated.  It may screw up the idle emissions of a fully warmed up engine.  Ive never taken the time to hunt that one down.

Now, back to the smoking rabbit.  It appears we have two problems:  (1) A sticky throttle lever.  (2) marginal (shot) injectors.

First the throttle lever.  Get a can of WD 40.  A big can of it.  ENGINE OFF. Disconnect the trottle cable from the pump.  Work the trottle lever back and forth while spraying the the shaft with WD40. This may take alot of cycles.  The continous spray of WD40 will help wash out the crud that is binding the small lever.  Keep going untill the little arm snaps back with no resistence.  Continue to spay and cycle the arm a couple three dozen times more.  Put everything back togather and report back here.

[jtanguay]

well actually the cold start lever increases timing up till 1800 rpm.  his model might have the idle speed boost as well, which in fact does give more fuel?  :wink:


i almost think that maybe the pump internals are shot, or in need of cleansing... get some lubromoly diesel purge.

[saurkraut]

Its an '81.  Idle booste didn't exist then.  As a mater of fact, i haven't seen any idle boost on any US mechanical pumps.

The advance below 1800 may change the RPM slightly,  like a phemto RPM, but i can't detect it on any of my stuff.  i can hear a slight increase in "nailing" when I pull my cold start when the engine is warmed up.  no noticable increase in RPM though.  So, no, its not getting any more fuel.

What he is describing, the little lever below the big lever hanging up, is classic old corroded pump behavior.  It is really common on the 1.5 pumps.  Working it back and forth, while spraying WD40 on it has worked for me.  Befor we toss the pump, lets try somthing simple and proven.

[rabbit_diesel]

Ya, when I finish rebuilding my Jetta motor, I might need to do a little adjusting on my pump.  I noticed when I was running it, before its reduild, it was running sort of crappy like reving when I even touched the throttle.  That's why I was so confused about the fuel adjustment screw.  But after I get my new rings, bearings, and seals in i'm sure that nothing underneath would go wrong (I might need a new pump), no more worries.  So, the problem with vegfuel's rabbit is probably that either the pump or injectors are bad.  Sorry about the comment on the cold start, I didn't even know that it advances the timing :oops: .  Well at least I learned something too.