Runaway? What next?

[benIV]

My 03 ALH sedan just had a runaway moment I think. I'm almost certain but I've never experienced one before and it was over so quick and it seems fine now so I'm not really sure if it was?

I was at a light and started off a lot faster than I ever normally do. I didn't stomp all the way down on the accelerator but i did go pretty hard on it, more than i ever usually do. When I hit third gear and let off the clutch is when I felt it go. It was like a huge boost so I let off the accelerator but then the engine just didn't stop and climbed real fast. It definitely got to the red line but I turned my attention to getting off the road so I wasn't sure how high it got to. As I pulled off the road and hit the brakes hard I remember seeing the tach dipping down almost to 0 as I came to a quick stop but then as I stopped it started running away again.

I think maybe it dropped because I had it in gear as I was stopping and then as I stopped and shifted to neutral it must've started back up again but I'm not entirely sure.

After coming to a stop I immediately dumped it into 1st and the engine shut down. I'd say at most 15-20 seconds elapsed from the first sign of runaway to shut down. I sat there for a minute and then tried to start it back. It didn't seem to want to start and sounded really weak. I tried once more and it started up with hesitation like it had a weak battery.

I drove it the mile or so home and it ran perfectly fine, through all the gears and all the stopping and starting at various the lights.. I didn't hear or feel anything different as I was driving home but I'm a bit concerned to drive it anymore until I can figure this all out and get it looked at and fix whatever caused this.

Is my engine done?How do I figure out the cause? What might it be? What do I do next?

 

[csstevej]

How much oil did you lose?

Take the bottom hose off the inter cooler and see if there’s anymore oil in there.

I‘d do a compression check to make sure you didn’t bend any rods from a partial hydro lock.

You could pull the valve cover and inspect the tops of the lifters for any spider web cracking ( probably won’t see anything, but doesn’t hurt to Look ).

If it all looks good and you didn’t lose more than a quart of oil I would run it and consider yourself lucky.
In the future don’t baby your car , you need to red line it once a week with a long pull to keep oil collecting on that lower boost pipe , either that or your turbo is starting to leak more than normal....... just my .02.

 

[ghohouston]

Make sure timing belt is still in tact before anything. If it is, next check the oil. Then turbo for oil in the intake or exhaust, and check for excessive shaft play. Beyond that, glow plugs need to be pulled, spin engine over a few revolutions (you can do it with the starter, just make sure to cut the fuel source, however you want to) or you can do it by hand. Many folks will say to do it by hand because it's safer, but I SERIOUSLY doubt anyone has ever bent a rod turning the engine over with the starter, with either glow plugs or injectors removed.The engine sounded weak when trying to crank back up because it was hydrolocking from ingesting oil into the cylinders. As quickly as you shut it down, the engine is probably okay, but a compression will tell you.

The turbo is probably trashed and caused this, although as csstevej stated, it could just be from accumulated oil in the c.a.c. and it was ingested.

 

[Jerry_T]

Is my engine done?How do I figure out the cause? What might it be? What do I do next?

Been here twice now, first time three bent rods and two valves. Compression check was well within spec but difficult cold starts with white smoke until it warmed up. Only found the bent rods after removing the head and measuring piston protrusion. Basic in frame rebuild.
Second time only one bent rod, turbo shaft broke causing this one. Waiting to be reassembled.

Unless there is a rod through the block, it is recoverable. All depends how much you are willing to do or pay.

To do the compression check you will need to pull the glow plugs. Once they are all out spin it over, if oil shoots out the holes then yes you had a hydro-lock incident. This happens when oil in the turbo passes by the mechanical seal, collects in the inner cooler and is blown into the engine under a high boost condition. If no oil shoots out, it passes the compression check and cold starts are ok, then drive it like you stole it, red line it regularly, and maybe this will not occur again. Would still be a good idea to check the turbo shaft play. A little axial movement is ok but no radial.

If you do need repairs and you do the work the repair should be manageable at $2 to $3k, depending on parts cost, new turbo vs used turbo and head repair. Pay someone else and it adds up to more than the cars value. Well book value, not sentimental value. I really like my little Golf!

 

[KLXD]

Oil blowing out doesn't necessarily mean it hydrolocked. It didn't stop so it didn't lock. Compression would have been higher than normal, maybe too high and things bent. Oil sloshing around in the cylinders could mess with the injection spray pattern and cause the difficult starting until it all burned or blew out.

Yes, you need to pull the plugs and spin the motor over until nothing comes out before a compression check. Oil sitting in the piston bowls will cause abnormally high compression and can mask a bent rod. Have to get it all out but since it seemed to run ok it's prolly already gone.

And next time or for other readers, to stall the engine you want it in a high gear but better to stand on the brakes in whatever gear it's in rather than waste time shifting to a higher gear and letting it rev up while trying to shift up.

 

[Nevada_TDI]

I had a situation kinda like yours...I didn't lose the turbo, thank God. It went into runaway so I shut it down and towed it home. A few days later I turned the key and started to turn over, and then it groaned and stopped. I pulled the injectors out, hit the key and the amount of oil that blew out of the cylinders really surprised me.
All was well after, and I was so grateful I learned from the people here what to do, and what not to do.

 

[nicklockard]

I had a mild runaway on my 99.5 Tdi--about 15 seconds total run time like that. I killed it with brakes in gear, drained oil from intercooler, and it ran fine after that. Never found out the true root cause. That turbo continued to function fine. One theory of mine is: babying these things lets lots of oil build up in the intake system. If you suddenly accelerate, it gets a big gulp of oil, starts to runaway, and pulls more oil off the intake soot and turbo seals.

Moral of the story: don't baby these things. Drive the dogshit out of them frequently.

 

[Poor King]

Kind of a contradictory situation these runaways, defying the very basis of why tdi's exist: the glorious mpg. So what would be the proper habitual art of driving them, a fine line that prevents buildup while not losing at the pump... 3krpm shifts?

 

[jmodge]

Moral of the story: don't baby these things. Drive the dogshit out of them frequently.

That's it right there, I see no significant difference in fuel consumption running them medium hard. you are most likely to cause driveline and boost control maintenance/repair issues lugging them.

 

[MukGyver]

the IC kind of doubles as a pee-trap until it fills up enough to become the supplier of propellant into the airstream. I also imagine oil coating the inside of the IC is not doing cooling any favors. oil is a pretty good insulator and aluminum does better if it can remain uncoated.

I was looking just now at how low the bottom of the IC sits in the vehicle, seeing if I could put a run off reservoir, or some kind of loop trap upstream but there's not a lot of room under there.

edit: and anything like that would have to handle boost pressures to boot.

 

[WrEkkED]

If it was my car, I would decide what the car is worth to me. At the very least your looking at a new turbo and I would budget to replace the head - this is cheaper than retrofitting your used head with new valves/lifters etc. - so at this point your looking at ~$5000. I wouldn't even bother with a compression check and just pull the head. The valves in these cars are very weak (good thing), and at that point you can tell if you bent a rod. You can have perfect compression with bent rods and bent valves to replace the turbo and 1000 miles later have a valve drop and total the engine along with your new turbo anyways. Hope the head is fine and save some cash. my .02

 

[csstevej]

If it was my car, I would decide what the car is worth to me. At the very least your looking at a new turbo and I would budget to replace the head - this is cheaper than retrofitting your used head with new valves/lifters etc. - so at this point your looking at ~$5000. I wouldn't even bother with a compression check and just pull the head. The valves in these cars are very weak (good thing), and at that point you can tell if you bent a rod. You can have perfect compression with bent rods and bent valves to replace the turbo and 1000 miles later have a valve drop and total the engine along with your new turbo anyways. Hope the head is fine and save some cash. my .02

Why a turbo.....you don’t know if it’s a problem or if the PO babied the car and the intake may be partial blocked?

In my experience rarely is the head damaged from this and doesn’t need to be pulled unless you see an issue.

You will not have perfect compression with a bent rod, no way in hell.

The only way I’ve seen or heard of valve bending is by direct contact with a piston. I’ve had several motors apart for bent rods , damaged pistons and botched timing belts. I am by no means an expert , but this is what I’ve found on the ones I’ve worked on.....I have 5 of my own that have had various signs of abuse before I had gotten them. Just my .02

 

[IndigoBlueWagon]

Although you've already driven it post "event", and because of that any damage that might have occurred may be done, if it were my car I'd not start it again until you check it out, or have it checked out. I'd:

• Of course look for codes, although that my not be that helpful
• Check oil level and drain the intercooler
• Check timing with tools to make sure the belt hasn't moved a tooth or more
• If timing has changed pull the valve cover and inspect the followers for damage
• If timing is good, run a compression test: this will help identify any bent rods or valves

If that all checks out, drive the car, run some logs and make sure turbo is boosting properly, check injector balance. Pay close attention to actual versus required boost as a faulty actuator or vacuum system might have caused enough overboost to start the runaway condition.

Finally, check interooler piping for leaks and intake for clogging. As mentioned above, you may have simply accumulated oil in the system by driving gently for a while, or the turbo vanes might have been sicky, allowing overboost. Driving these cars hard once in a while or letting them get good and hot on a long highway run (by long I mean hundreds of miles) is good for them.

Good luck!

 

[WrEkkED]

I am far from an expert neither, that being said talking to lots of people who tracked their TDIs most of them ended up with slightly bent rods and never had any compression issues. It depends on the severity of the bend. That being said, you can most certainly bend a valve with a runaway not that that is the most common case - point in case post #4 above, but like I said in my opinion (opinions are like... LoL) not a risk I would personally take. I wrote about my timing belt skipping in another post here, but anyways once we reset timing compression was perfect, pulled the valve cover no signs of damage, even with a microscope. I said lets just replace the head. When I got it off 2 bent stems, 1 cracked.

As for the turbo, again depends on what the car is worth to you. Would you risk that maybe you were just too light footed only to have it run away on you again? What if this time you run someone over or hit another car, or it happens on the highway? For $700 to me it's a no brainer.