Runaway Questions

Just had my TDI try to runaway on me. Highway driving, started spewing white smoke (it's -30*C here so hard to know what was coming out of the pipe)
Just filled the fuel tank, drove about 6 miles and it was running fine although I could swear I smelled raw diesel. Then turned onto the highway and had a hard time shifting into 3rd. By 5th gear it started pulling HARD. I used the brakes to slow it until it sounded like it was labouring real hard (and I was catching up to a semi) and used the ignition to shut it down. The engine hard locked like it was full of fuel or oil.
Do turbo's fail bad enough on these little engines to cause this?
Does the injection pump or an injector fail bad enough on these to cause this? I'm a HD tech, I know more about engines with turbos the size of this engine so I need advice. Waiting for it to warm a little outside then I'll push it into the garage for a diag...

Sounds like an issue with the injection pump. If it was running away on motor oil, killing the ignition switch probably wouldn't do much.

The 'shuttle launch' of white smoke billowing out the tail pipe, is a blown turbo... almost exclusively.

The easiest diagnosis is to pull the pipe from the intercooler and watch the oil pour out. It might have already poured out the tail pipe...

Also, remove the pipe from the air filter to the center of the turbo. It helps to buy a pair of cable driven spring clamp pliers. The spring clamps, which we prefer to use, are not all that easy to get to without the right tool. With the air pipe out of the way, you might just see a broken off compressor wheel with an inspection mirror. Otherwise, reach in with index and middle finger and see how much the shaft moves. If you can stall the wheel against the housing, or there is any lateral play in the shaft, remove and replace the turbo.

Whenever a runaway happens, there is a high risk of bending a rod. It is possible to defeat the oil feed line to the turbo ( think it's blown anyway), clean out the excess oil in the engine and see what compression you have. If #2 or #3 cylinder are very low, you are pulling the head and removing the bent rod.

I think the smell of diesel is a secondary issue. I'd be looking to see if there is fuel around the injection pump head or leaking from the Injection quantity device. Any runaway from the turbo can cause a secondary fuel leak, due to the unusual high rpm associated with a runaway.

Yup.

As part of the diagnostics you can remove the glowplugs and turn the engine over by hand (19mm socket on crankshaft sprocket bolt) to see how much oil comes out of each hole. Unfortunately it only takes a couple tablespoons of oil to bend a rod.

A bent rod will also generally make itself known via a compression test.

Well, you guys have all hurt my feelings. Lol.

I guess I'll just scrap the engine. I have another on a pallet, time to put it on a stand and prep it. Being a beetle it'll be a much nicer job of replacing the timing belt before installing it lol. Bearings and rings while I'm playing with it!

turbobrick240 said:

Sounds like an issue with the injection pump. If it was running away on motor oil, killing the ignition switch probably wouldn't do much.

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I had thought this as well. My guess though is that cutting off the fuel reduced the power enough that the brakes finally stalled it. But with both fuel and oil it was accelerating through

Franko6 said:

I think the smell of diesel is a secondary issue. I'd be looking to see if there is fuel around the injection pump head or leaking from the Injection quantity device. Any runaway from the turbo can cause a secondary fuel leak, due to the unusual high rpm associated with a runaway.

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I didn't over-rev it. It never went over 3500, as was able to kill it in advance (clutch in only after it locked up)

Eli.krahulec said:

I didn't over-rev it. It never went over 3500, as was able to kill it in advance (clutch in only after it locked up)

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That sounds like you were running on turbo oil. Great job controlling it as you did!
Pay particular attention to cyls 2 & 3. They tend to get the most in a turbo runaway.

Yeah, if it locked up hard, I'd just scrap it and toss in that spare motor.

A runaway causes black smoke, not white.

My guesses:
Pissing injector or fuel line restriction causing air in the fuel.

Have you tried to start the engine?

Did you check the EGR to see if it was partially closed? My experience with a faulty EGR resulted in loads of white smoke and raw diesel odor!

What is the oil level on the dipstick?
Take the serpentine belt off and try and rotate it by hand. Pull the glow pl lugs and rotate by hand.

There are a few things that can lock up and engine from the outside.
If it was running as you stalled it out vs just shutting off you might not have bent or damaged anything.

If you can free it up aka turn it by hand, take the charge pipe off the turbo and start it up.

I'd say you have a really good chance of the engine being fine.
Also just for kicks what does your timing belt look like?

White smoke can be from over fuel but probably from the oil. Wish you had killed the ignition initially to verify fuel vs oil.

I haven't looked at it yet. It's still cold out, can't get my skidsteer started to push it inside. Borrowed a compression tester this afternoon, going to see what's left of it soon.

AndyBees said:

Have you tried to start the engine?

Did you check the EGR to see if it was partially closed? My experience with a faulty EGR resulted in loads of white smoke and raw diesel odor!

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I can guarantee it's not the Egr. Mine is, um, MIA.... lol.

As a mechanic, I hesitate "trying" anything until I have a better idea of what went wrong. I'll get it inside hopefully tonight and know more soon.

Thanks everyone for the help, I'll post the results!

Eli.krahulec said:

Just had my TDI try to runaway on me. Highway driving, started spewing white smoke (it's -30*C here so hard to know what was coming out of the pipe)

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NOT A RUNWAY. Burning oil is burning oil. Nothing more. (Even gasoline cars do burning oil. ). A runway would have zoomed to 5000 rpm even if you were off the throttle.!!! What you experienced was some burned oil (even gas cars have that),
Calm down and breathe

Forgive BeetlePD for he knows not what he sayeth.

BeetlePD said:

NOT A RUNWAY. Burning oil is burning oil. Nothing more. (Even gasoline cars do burning oil. ). A runway would have zoomed to 5000 rpm even if you were off the throttle.!!! What you experienced was some burned oil (even gas cars have that),
Calm down and breathe

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dude. gas engines will burn some oil mist but not nearly anything close to 20% of it and that's probably a high estimate. diesel fuel and motor oil have almost the same flash point. gas cars can't run away because it needs a spark, unless things got crazy im sure it could happen but i dont know of any gas car ever doing so.
i have had a runaway on me but i stopped it after almost a half mile of on the brakes in 5th gear. thats what i get for running 32PSI on a crazy setup. thank god for that SBCIII and Hawks pads or i dont think i could have stopped it.

you are the one who needs to calm down and breath, into a paper bag.

flee said:

Forgive BeetlePD for he knows not what he sayeth.

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I'm sure he does. he may just end up reaping what he sows.

He said there was white smoke, but the engine did Not goto redline, do itvwas not a runaway

.

Eli.krahulec said:

Just had my TDI try to runaway on me. Highway driving, started spewing white smoke (it's -30*C here so hard to know what was coming out of the pipe)
Just filled the fuel tank, drove about 6 miles and it was running fine although I could swear I smelled raw diesel. Then turned onto the highway and had a hard time shifting into 3rd. By 5th gear it started pulling HARD. I used the brakes to slow it until it sounded like it was labouring real hard (and I was catching up to a semi) and used the ignition to shut it down. The engine hard locked like it was full of fuel or oil.
Do turbo's fail bad enough on these little engines to cause this?
Does the injection pump or an injector fail bad enough on these to cause this? I'm a HD tech, I know more about engines with turbos the size of this engine so I need advice. Waiting for it to warm a little outside then I'll push it into the garage for a diag...

Click to expand...

BeetlePD:
This was a runaway that was (barely) caught in time and controlled.
Your opinions are uninformed and of little value to actually solving your problem(s).
Read more, opine less.

Well, finally got around to inspecting things. Oil filter housing is not attached to the engine any longer. Pieces hanging out of that hole.

Thanks for the help.

And BeetlePD read the remainder of the post. It did run away. But being a manual and in 5th gear I was still increasing in speed with the brakes applied

Eli.krahulec said:

It did run away. But being a manual and in 5th gear I was still increasing in speed with the brakes applied

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Yuppers. BTDT... an amazing amount of torque.

Eli.krahulec said:

Well, finally got around to inspecting things. Oil filter housing is not attached to the engine any longer. Pieces hanging out of that hole.
Thanks for the help.
And BeetlePD read the remainder of the post. It did run away. But being a manual and in 5th gear I was still increasing in speed with the brakes applied

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Carnage pictures... id love to see them. Sorry for your loss. rip little engine.

Mongler98 said:

definition of a runaway
A Diesel engine that has had its ignition turned off and fuel from the tank and injectors stopped but the engine continues to run on the engine oil from the crankcase (usually increasing RPM's).

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He said he switched the ignition to off, and it stopped.

By your own definition, that is not runaway (else the car would keep running)

BeetlePD said:

He said he switched the ignition to off, and it stopped.

By your own definition, that is not runaway (else the car would keep running)

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With all due respect, I think you may have missed one of the tell tales of a runaway....

He did say " By 5th gear it started pulling HARD."

And if his ASV is working properly (I know it's rare, but not impossible), wouldnt it stop the engine from sucking oil when the key is turned off?

dont bother arguing with this bettle PD guy, he only choses to listen to mechanics who tell him things he wants to hear. he wont read your posts, he will go resurrect a 20 year old thread for his 20 year old tune

I was using Mongler’s definition which said “has ignition off.... but engine keeps running”.

i thought you only paid attention to mechanics, looks like you are just trying to start a fight, again. just let it go man. maybe you will be happier on another forum where you can rant and rave with others. not here. not cool.

BeetlePD said:

I was using Mongler’s definition which said “has ignition off.... but engine keeps running”.

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If you read his post it locked up as he turned the key off. very dangerous to kill the key (and risk locking the steering wheel) while going down the highway. he had it in 5th gear with (im assuming) both feet pressing as hard as he could on the brake trying to stall the engine. Who knows if his asv has been deleted. So shutting the key off may have done no good at all. Apon inspection he found physical damage to the engine. Proving some mechanical fault caused it to runaway. A broken injector can cause one to runaway.

Please, stop arguing and just accept that this motor ran away.
have you seen a runaway diesel in person? it is one of the most panic inducing things. Even if your prepared for it. I was the kid with the board by the intake while an old detroit was trying to get started. even with the board totally covering the intake it was still able to pull enough air to run. the fuel rail bar thing under the valve cover was stuck and didnt return on all cylinders. Granted its not a Real runaway because it wouldnt have gone past redline because it was still governed.

BeetlePD said:

I was using Mongler’s definition which said “has ignition off.... but engine keeps running”.

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You want to be litteral??? A Diesel engine runaway is a rare condition affecting diesel engines, in which the engine draws extra fuel from an unintended source and overspeeds at higher and higher RPM and producing up to 10 times the engine's rated output until destroyed by mechanical failure or bearing seizure through lack of lubrication.


Diesel engines can combust a large variety of fuels, including many sorts of oil, petrol, and combustible gasses. This means that if there is any type of leak or malfunction that increases the amount of oil or fuel unintentionally entering the combustion chamber, the quality of the air-fuel-mixture will increase, causing torque and rotational speed to increase.

Fuel and oil leaks causing engine runaways can have both internal and external causes. Broken seals or a broken turbocharger may cause large amounts of oil mist to enter the inlet manifold, whereas defective injection pumps may cause an unintentionally large amount of fuel to be injected directly into the combustion chamber. If a diesel engine is operated in an environment where combustible gasses are used, a gas leak may result in an engine runaway if the gas can enter the engine's inlet manifold.


Another way the engine can run uncontrollably is caused by wear and neglect. As piston rings wear, they allow a minute amount of oil into the combustion chamber, as with most internal combustion engines. But if the wear gets to the right level, and the diesel engine gets hot enough, it starts to vaporize the oil in the crankcase and it leaks passed the piston rings. Once in the cylinder and combustion chamber, the vaporized oil acts like diesel fuel and ignites under the extreme compression. Once this happens, the engine will go until the oil has been exhausted and/or it blows up, whichever comes first.