Diesel Engine run away

[A Guy]

Hello group.  I'm a newbie to this group.  I was directed here from another VW group. As this one is diesel specific, I hope I can solve my delema.  
I have a 91 Golf with a 1.6L.  It just turned over 200 000Km.  It runs well and smoothly with only a small puff on start up.  
My problem occurs on the highway and so far only when in fifth gear.  Suddenly without much if any warning the car will take off and at the same time emit a massive cloud of smelly, thick smoke.  All I can do is take my foot off the gas and let it burn out.  The engine usually races for a second maybe two and then all returns to normal with the exception of the choking motorcyclist behind me :oops: .  I want to know why this happens and what I can do to fix it from happening.  Today it happened again on my way into work but this time it lasted a second longer than normal.  Any and all advice is greatly appreciated.
thank you in advance.
Greg

[fspGTD]

It's happening from oil getting into the combustion chambers and being burnt as fuel instead of the diesel.  If not addressed and it runs away without you catching it, the motor can over-revv which can cause expensive engine damage.

Easiest fix which might work (you could try) is improving the crankcase breather system.  This thread has some ideas along those lines:
http://www.vwdiesel.net/phpBB/viewtopic.php?t=1490

If the problem persists even if you've removed all blowby oil vapors from being introduced into the air intake (easy enough to try), the piston rings probably aren't scraping enough oil off of the cylinder walls and it's time for a piston re-ring, if not an engine rebuild.  Other possibilities of oil getting into the combustion chambers are bad intake valve seals, or bad turbocharger compressor seal (if you've got one of those.)

[A Guy]

Finally! now I feel like I'm getting somewhere.  thank you.  I noticed similarities from the pics the kid took of his dads mods but I'm lacking the turbo so theres way more room and way fewer pipes.  I'll have a look tonight and see what I can figure out.  Thanks again for the info.  

[VWRacer]

The kid? I think he's talking about you, Jake!  :mrgreen:

[A Guy]

No disrespect intended :oops:
I had a closer look last night and noticed I don't have the same hoses due to the fact I'm not running a turbo.  I have one hose that comes out of the top of the valve cover then runs down under the air box where it splits at a 'T' horizontally and drops down into the intake at two points side by side about 6" apart.  This is the only breather hose I have(from what I've noticed so far).  WHat can I do with this set up to eliminate the engine runaway?  I have already removed the hose and cleaned it out.  I have not removed the valve cover to see if the hole is blocked at the entrance point.  I continued to get runaway after I cleaned the hose.  
Thanks for the replies thus far.  
Greg

[fspGTD]

Hey now, just because I help my dad with his car doesn't make me a kid!  :lol:

Cleaning the hose won't do much.  If you really want to insure you aren't getting oil into the intake, remove that crankcase vent hose and block off the entrance points on your intake manifold.  You might want to route the hose carrying the crankcase vapors down low underneath the car as it will be emitting oily (and stinky) vapors, opposed to letting it spew oil vapors high in your engine compartment.  Then you can drive it on the freeway like that and see if it fixes your runaway problem.  If that helps, you could buy and rig up a better crankcase vent filter.

You can also add a crankcase vent hose to the side of the block, as shown in previous thread.

[A Guy]

"If you really want to insure you aren't getting oil into the intake, remove that crankcase vent hose and block off the entrance points on your intake manifold"

When you say "remove the hose at the crank" are you referring to the valve cover output or am I not looking in the right area :?:
Thanks
Greg[/quote]

[fatmobile]

He's talking about the valve cover hose that you described going to the intake.
 Block the intake holes and run that hose somewhere else. Take it for a drive and see if it still takes off on it's own.
 You probably still have the cam splash shield on yours right?
 Pull the valve cover cap and see if there is a piece of black plastic just under the valve cover.
 There are small restrictors inside those crankcase vent holes, in the intake. I've never heard of anyone having consistant runaway problems with a 1.6D. I thought these restrictors would limit the amount of crankcase gasses allowed into the intake.
 Normally the pressure inside the block becomes great enough to push oil out the dipstick, due to the restriction in the intake ports. I've drilled these restrictions out and got the oil to stop coming out the dipstick and still didn't get it to runaway.
 Anyway, pull that hose, plug the intake crackcase vent holes and let us know what happens. Remember to run the vent down low to limit the fumes coming out your hood when you come to a stop.
 How's your oil level? When the 1.5 was running away, I lost alot of oil as it was being used for fuel.
 How's your fuel filter? A bad fuel filter can let air into the pump and weird things can happen.
 When my car ran away, taking my foot off the gas didn't stop it, shutting the key off didn't help. I had to step hard on the brakes and bring the car to a complete stop. Then every time I started it, it would run away again ... till the oil in the intake was burned away. Then I could start it and drive on ... till I hit 60mph and it would happen again. I got quite a parade going all the way home from New Mexico and if I got going 60, it would take off and leave them all in a huge cloud of smoke. People pulling over, thinking I blew the engine but I would just wave them on, ha.

[A Guy]

Thanks for the clairafication.  I don't know if the splash sheild is in place.  I'll look.  I get oil coming from the dip stick too.  I thought it was because of the runaway causing it to over rev thus more pressure...
I haven't checked the fuel filter.  I don't think I can inspect it.  I'll have a look and possiblty just change it but the car runs very well aside from the runaway.  At what frequency should i change the fuel filter for future reference.  
I completely hear you about the parade of cars and the stares.  I've gotten some very displeased looks as the finally catch up and pass me.  The truckers laugh as they seem to know what's going on.  The motorcyclists hate it!   :oops:
I'll have some time on sunday to do some work and I'll update.  Thank you for all the help.  
Greg

[fatmobile]

I put a vaccum gauge on the fuel line and when the pump starts pulling near 3" hg., I change the filter.
 No point changing a $10 (or more) filter till it needs it.
 When there is enough pressure to push oil out the dipstick, it can also push seals out. I saw the I-shaft seal pushed out on the engine previously mentioned and wondered why ... till I got the engine in and started.

[chrissev]

I put a vaccum gauge on the fuel line and when the pump starts pulling near 3" hg., I change the filter.
 No point changing a $10 (or more) filter till it needs it.
 When there is enough pressure to push oil out the dipstick, it can also push seals out. I saw the I-shaft seal pushed out on the engine previously mentioned and wondered why ... till I got the engine in and started.

he's lucky he's not running a turbo.  Blowby on turboed engines with worn out rings can be quite impressive.

[toomanycars]

You have to be brave to try this solution...

http://www.vwwatercooled.org.au/vwforum/viewtopic.php?t=325&sid=d6e7fa3912ee7408c391e888bba82e7f

[A Guy]

Ok so I ran the bypass and I have logged just shy of 300 Km  at speeeds between 110Km/h 125km/h.  No runaway.  This is good I think because it only happened around these speeds.  If I go this week (1500kms)with no runaway I will install the can with the steel wool that was posted previously.  
Also, I looked in the valve cover and there is a splash shield and I could see a small hole in line with the vent.  Is this what was drilled out?  Did it help the oil from coming through the dipstick?  
Thanks all!  Please keep you fingures crossed for me.  
Out!
Greg

[fatmobile]

I could see a small hole in line with the vent. Is this what was drilled out?

 I'm not sure where you saw a small hole.
 The restrictors I'm referring to are in the intake, where the crankcase vent line connects to the intake manifold. Comes from the valve cover, splits into 2 lines and enters the intake. Pull the hoses and look down the intake ports. You'll see that the gasses escaping the block are limited by restritions in these ports.
 Drilling out these restrictors in an '85 Jetta diesel engine I was messing with stopped the oil from coming out the dipstick. Take note that this engine did not have a runaway problem, like yours might. The engine I worked on lasted 2 more years before compression got too low to start. Yours might take off like a bat out of hell if you drill the restrictors out. I always wondered if these holes were used to limit crankcase gasses from entering the intake, preventing runaway. This might explain why your runaways were controlled. After drilling out the restrictors, I took the car for an 80mph drive to see if it would runaway ... it never did till the day it died (required a pull start).
 Since yours might have been actually running away, yours might take off uncontrolled if the resctrictions are drilled out. If it does, letting off the accelerator won't stop it.[/quote]

[A Guy]

Gotcha.  I had looked into the exhaust on top of the valve cover.  There is a plate directly below and there is a pencil sized hole in this plate.  I'll look in the holes in the intake on my next day off (when I'll do the fix) presuming my runaway problem stays solved.  
The car is running very well.  I'm over 400k (keeping with traffic) with no runaway.  
I'll keep an eye on the oil coming from the dipstick in the meantime.
Have a great day folks.
Greg