81 rabbit runaway

[newbugdude]

81 rabbit with 60k hydraulic motor. I recently replaced the IP with a rebuilt one from "Prothe" (I should have done my homework on this dude) and since have had nothing but trouble. What I thought to be sticky throttle was not, it was the feared "runaway" happening to me while on my way home from work. Managed to get motor to calm down after about what seamed to be a 1 minute battle (probably 30 seconds) to forcefully stall the engine. However, things just arent the same after that. Basically I managed to limp it home and now I cant get it stareted unless i tow it. Any suggestions will be greatly appreciated. Im not sure where to start. Thank You!

[Quantum TD]

Well, runaways are usually caused by bad compression rings/worn bores which lead to the engine running off crankcase oil, rather than the fuel.

But, since you bought your pump from prothe, I'd venture to say you got one of his classic (profanity removed by moderator) pumps. By all accounts, some of his stuff is bearable, but he claims to be able to build pumps, but has (more profanity removed) no idea what he's doing. You're not the first in this boat.

Sticking pump internals can cause a runaway. It's less frequent, but if someone screwed with the internals, and/or the internals have rust issues, it's more likely to occur than under normal circumstances.

My first questions would be:

Why did you replace the pump in the first place? Was the old pump not working at all, or was it just leaking? If it was simply leaking, how did the car run otherwise before you installed the prothe pump?

When the car is running, pull the intake hose off the valve cover. Are there plumes of white smoke puffing out? If so, it could mean your bottom end is the problem. Generally, the hydro motors have better casting material, and tend to have bore/ring issues less frequently than the earlier Brazilian blocks used in the Rabbits. In my non-scientific research on the topic, runaways from worn rings/bores happens alot more frequently on the earlier mechanical-lifter blocks (especially on the 11mm blocks). But, that's just perception, experience, and observation of others experiences talking here.

In general, give us all the history you know about the vehicle, and we'll go from there.

[82vdub]

You may also want to check the glow plugs. I've read (no experiece with it) that after a severe case of runaway, the glow plugs can be completely melted away, thus hard starts. However, if you do try to start the car, be prepared for some means for shutting it off, either by cutting off the fuel (if it's IP related), or killing the air source (will always work).

[bscutt]

Check timing to make sure it did not jump a tooth when in runaway. You can jump one tooth without damage in my experience although maybe not at 10,000 rpm!

[Fatmobile]

Yep, glow plugs tips are probably burnt off,..
and the injection pump timing can jump a tooth without hurting anything.

Pump probably didn't cause the problem.

[davidpa28140]

I once had a pump rebuilt by a bosch pump shop in Clearfield PA . It took them 3 months to do it and it suffered this same problem. It was on an engine with low miles and was for sure a pump problem. When it ran away it made a more black smoke than the classic "oil burning" runaway does. I got it stalled out before it went postal but it is still alarming. I agree with the other guys you should check out the glow plugs. Also, I have to agree with the other guys that the oil burn runaway is far more common, check and see how much oil is on your air filter, if it's wet I would lean towards worn rings.

I ended up buying an off the shelf unit from Jack and had no further problems.

[hagar]

newbugdude : Why do I hagar enter this Fur-Ball called Run-Away discussion ? Think "Prius" and "Rabbit" .

Nothing but Nothing tickles my funny bone more than memories of a VW 1980 Rabbit "Run-Away" . .Was it dangerous and irresponsible of me to drive that thing home from the muffler shop ? I plead guilty.

After I get a feel for the numbers of members who wants to read that tale , I may write it again.

READ MY LIPS it can be dangerous , you may kill some innocent bystander. SO ? do your homework.

hagar.

[newbugdude]

Thank you all so much for your posts on this. I am now ready to humbly share with you the actual findings and solutions to this matter.

Ok for starters I decided to buy new (rebuilt) bosch injectors and new duraterm glow plugs. I had chinese prothe injectors that I may have failed to mention. Anyway, I figured I can look for damages and signs of what caused the problem as I installed these new parts.

So the first huge sign was on the first thing i took off. The air filter; it was soaked with oil. Now I have read enough on this forum to know that my motor will run off that oil soaked filter (and it was). Next I remembered reading about crank vent block off plates and NOT much to my suprise mine was "blocked". I installed a vent plate and hose up to the air box and all is well.

Now time for injectors...yes i had chinese, no i wouldnt again, but the biggest problem was that I installed the heat shields upside down when i put them in. Yes and there were only 1 1/2 pieces left. Say what? Yes I did! Basically the spray discintegrated them. From what I've read and inspection on the remains.

Working from top to bottom and because it just makes sense it was now time for new glow plug install. What I found was that the "runaway" event left my glow plugs "plugless"...meaning all the ceramic electrodes were totally gone. Thats why it wouldnt start. Plus the injector spray pattern was wacked out because of the heat shields being upside down and gone and just not right because of me.

Now to bring it all together. I correctly installed all the above mention parts and the same prothe pump (which I must now humbly admit works great) and my bunny's jump'n again. Seriously the best its ever run.

BTW "runaway" is no joke!!! Very dangerous...I was on 15 fwy in CA during commute hours when this happened. Everybody behind me was stopping (including semi trucks) and pulling to the side of the road because they couldnt see through all the black smoke. I stopped the fwy. It was a minute of shear adrenaline "man vs. rabbit" power struggle that I never want to do again. But thankfully everything is ok and i'm wiser because of it.

Thanks Again Everybody!!!

[82vdub]

Thanks for taking the time to post your findings and results. This will surely help someone else in the future.

[hagar]

Yes it sounds like you had a genuine RUN-AWAY just a few comments.

No it did not run on oil on Filter , it ran on oil from the Crank case.. Amazing the HP a little engine like that will produce EH ?

Top rings are usually the problem. .. Stop remove cv line and drive home. , Simple EH ?.

hagar.

PS : the sicko.

[newbugdude]

Thank You Mr. Hagar for pointing that out. You are absolutely correct about the motor not runing off the oil in the filter but rather from the engine. Very good catch on that.

I will add to that with this: The oil soaked filter was merely a clue which i used to resonably deduct that the engine was running off the motor oil and thus leading me to start thinking "vent" or lack there of...I won't quit my day job just yet!

BTW I would like to hear your "runaway" story.
Thank You!
Newbugdude