ALH issue

[oprn]

I had a runaway between gears on my beloved ALH TDI. I was gum booting it off the on ramp to get ahead of a string of big trucks and between shifts something stuck and the tach momentarily hit the top end. 3 seconds perhaps. Huge cloud of black smoke! Then everything seemed normal.

Now the engine knocks a bit and sometimes misses on cold startup for a minute or two. Once on the road it drives and sounds normal. Good power and smooth but something is not right.

I took the valve cover off last night looking for a cracked lifter... all good. The sound seems lower in the engine to me. If it were a rod bearing it should get louder as the oil warms up and thins out. It should also progress quickly but I have put about 700 km on the car since the incident.

Do I have a cracked piston, broken ring/ring land?
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[TDCTDI]

Excessive oil buildup in the intercooler, either due to never having been drained, or a turbocharger that suddenly shit a seal or shaft will cause this scenario.


High RPM/load caused enough air flow to pick up the oil & then deposit it into the cylinders. Oil in liquid form does not compress enough in the combustion chamber & usually results in bent connecting rods.


Remove the lower hose off the intercooler to see how much drains out. If full, check your oil level. If it’s low, this is a sign of turbo failure. (This can also happen if the oil level was significantly overfilled.)


If there is lots of oil in the intercooler, do a compression test, or remove the oil pan to check for bent rods.
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[oprn]

Yes there is plenty of oil in the intercooler. Always has been. In fact I have owned 4 TDIs now and the intercoolers have always been oily. I have been told that is normal. However I believe you are correct. This one is extra oily and the engine has been using more oil than usual the last while. And yes whenever I get aggressive on the throttle it did smoke for a second or two. I wondered about that.

So now I see what has happened. The extra oil in the intake caused a runaway which shifted more oil into the intake etc. the turbo is still spooling well and the engine still has good power but the turbo shaft seal is done. Now with a bent rod a cylinder or two is down on compression and slow to fire cold. That explains the miss on startup on cold mornings.

Is the rod going to be bent enough that it will be visible to the naked eye when I take the pan off?

Also, what part does that butterfly in the intake play in this whole fiasco? I believe it to be part of the EGR system but would it not hold a partial vacuum on the turbo at times and increase the load on the turbo shaft seal?
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We had the stone age, the bronze age, the industrial age and now we are in the age of mass deception and mind control for corporate profit. (The mass media age)

[TDCTDI]

Yes, a connecting rod bent enough to cause rough run should be visible.


My wife was accelerating up an entrance ramp when the turbo on her car failed, that engine stopped dead instantly. Upon tear down, all of the rods were bent into “S” shapes, two of them were bent so bad that the counter weights on the crank sheared them in half.


Oil accumulation is common, I always made it a habit to drain & mop out the bottom of the intercooler every so often.


The “anti-shudder” valve only actuates to block off air flow upon shut down… to ensure that the engine actually shuts off, or to keep it from running away. It doesn’t do anything while the ignition is on.
_________________
Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


GOFUNDYOURSELF, quit asking everyone to do it for you!


An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.

[oprn]

If I were to freshen this engine up for a few more miles can the turbo shaft seal be bought? Not sure what route I will take, just weighing my options.

I also have a spare engine but no history so no idea what condition it is in. If that seal is a weakness then it would make sense to renew it.
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We had the stone age, the bronze age, the industrial age and now we are in the age of mass deception and mind control for corporate profit. (The mass media age)

[TDCTDI]

The seals are not available separately, but you can buy a cartridge fairly cheap.



https://www.ebay.com/itm/314961161036?chn=ps&_...bXEALw_wcB


If the seals are bad, it’s likely due to failed/failing bearings or wallowed shaft. I wouldn’t trust it.


I have installed a few of those Chinese cartridges without issue.
_________________
Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


GOFUNDYOURSELF, quit asking everyone to do it for you!


An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.

[oprn]

I tried separating the cartridge from the exhaust manifold on the spare engine to see if the turbine side was coked up but it is seized in there hard. Any tips on breaking it loose?
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We had the stone age, the bronze age, the industrial age and now we are in the age of mass deception and mind control for corporate profit. (The mass media age)

[TDCTDI]

Eh, be careful, the stainless-ish bolts they use are substantially softer & more likely to shear than any other similar size hardware used on these cars.

Drop the turbo in some ATF or penetrant for a few days & let it soak.
_________________
Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


GOFUNDYOURSELF, quit asking everyone to do it for you!


An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.

[oprn]

The bolts came out just fine, I just can’t seem to separate the spool from the housing on the exhaust side. Afraid to get too rough for fear of cracking the cast iron exhaust manifold.

That Chinese cartridge is super cheap! I know you said you have installed a few but is it something you would have enough confidence in to keep and run yourself?
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We had the stone age, the bronze age, the industrial age and now we are in the age of mass deception and mind control for corporate profit. (The mass media age)

[halfassleatherworks]

Oprn, I know that my Big Cat and Cummins engines are much larger then yours, but they are the same. they hammer rod and main bearing's. we always rolled in new rod and mains at 500,000 miles as a precaution. as you say you had a runaway I would at lest put in new rod bearings.
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[TDCTDI]

[oprn]

Thanks! I will give that a try when we get home on Wednesday.
_________________
We had the stone age, the bronze age, the industrial age and now we are in the age of mass deception and mind control for corporate profit. (The mass media age)