MK11 Toledo 1.9tdi Suspected Blown Turbo and Runaway

Hi,

I have a 1.9 TDI MK11 Toledo and when I bought the car the turbo was disconnected. I removed the manifold and turbo, cleaned and freed the vanes. Once back together I checked the actuator with a vacuum tester and it worked perfectly and arm moved freely.

I connected all of the vacuum pipes, checked the N75 valve was working and tested the vacuum pump.

All working fine. I took the car for a drive and you could really feel the "boost" when taking off from a standing start, i.e in the lower revs. That was never there before. So all good and I decided to test it up a hill. I did so but just after I started the hill I could hear what sounded like the turbo give a massive boost and a noise then the car went into runaway. I have had a car before where the car went into runaway from a failed turbo and it was a proper runaway. It kept going for minutes until it killed itself and you could not see the car cause of the smoke around it.

In this instance, I removed the key it ran away for about 10-15 seconds then stopped. It produced a good bit of smoke but nowhere near a proper runaway. Did the anti shudder valve kick in, how long before it kicks in normally?

Anyhow she wont start now and I know I should not to try to start her.

Its like she overboosted and blew the turbo and this caused oil to fire through and runaway? How can this happen if the N75 valve is working properly and vanes working properly?

And what damage will have been done?

Thanks

Barry

I am afraid to ask but would a replacement N75 be the issue? I got a secondhand one, same connections, fittings etc but a different model number.

Would this allow more air through? I presumed the ECU would still tell it to open and close when it wanted to and it should not make any difference?

Only thing that will stop a runaway is a prepaired driver and a good clutch and being in a gear and NOT shifting out of neutral, I'm assuming yours is an automatic? No possible way to stop one unless you install a reverse throttle body shutoff for such reasons.
In any situation of a runaway that revs out of control, the engine has a very high chance of being trashed. Bent rods, scorn crank, gacked cam, busted lifters, you name it, these engines cant handle revving past 6000k even for an instant let alone 15 seconds more more

Thanks for the response.

It is a manual.

I know the damage has to be assessed and no one can know till I take it apart.

I am more interested as to why it happened? I do not understand why.

I would say since you think it wasn’t a “proper runaway” that some oil had accumulated in the intercooler piping which of course is normal. With the turbo disconnected there was no longer enough pressure to blow the normal oil accumulation through the engine.

So when you hooked everything back up and didn’t clean the intercooler piping out what oil that was already pooled in the lower pipes because the turbo wasn’t being used blew through the engine and caused a “mild runaway” .

I agree with that.
OP. A runaway happens from 2 reasons, usually the first.
The turbo has what's called a journal bearing, in short it's normal for a small amount of oil to make it past and into the intercooler piping and gets consumed by the engine. When the bearing goes bad from wear it will push more oil into the system and feed the engine with an unmetered amount of (fuel) engine oil and cause this runaway that self feeds until the oil is lost like in your past proper runaway.

The 2nd is from ccv (crank case vent) from excessive blowby or just from not running with the turbo connected for a while. You can mitigate most of this with a proper catch can but under normal operational and even into performance setups it's not nessasary, it's a bandaid to solve a problem that should not exist.

Hi,

Thanks for the replies.

But why did I overboost, hence blowing the turbo?

Vanes ok, actuator ok.

Could the wrong n75/turbo control valve be a culprit?. Looked the exact same as the old one, same fittings etc etc but different model number.

Barry

Hello,

I need to check the oil seal on the turbo but I believe it has had the runaway from oil in the intercooler.

Anyhow I have started removing the oil pan, (not fully removed as a I need a swivel 10mm for the last two bolts) and I have completed a compression test. The tool is a cheap enough tool but it should perform the same across all cylinders;

#1 380
#2 300
#3 300
#4 200

So I assume from this cylinders 3-4 have issues?
If I had read 300 in #4 would the car have started?

Could I have three bent rods in 2-4 from a 10-15 second runaway or could this be something else?

The car will crank on the starter but when I try to turn the engine manually on the crank bolt I can get almost half a turn before it wont turn any more. ( I am not using a breaker bar as the engine should turn using a simple ratchet and a bit of force?)

Thanks

Barry

If oil was already pooled in the intercooler the engine sucked it out and burned it up till it was gone resulting in an overboost.

If the compression tester was accurate or close, based on those numbers you have 3 bent/damaged rods and maybe even all 4. The readings in each cylinder if they are similar to the North American models should be around 450.

A runaway may not have killed your turbo, you’ll have to check it to be sure, but it added to much oil into the cylinders causing the rods to bend.

In any case you’ll have to pull the head to check. This is what mine looked like after loosing 8” of teeth on my timing belt. Notice the shiny area where the valves hit the cylinder top?

j

380 is still borderline too low for that engine. Were talking 480 is about where it needs to be. Yea, with numbers that low, your rings are probably shot and or bent rods.

Thanks for the responses and pics.

I am relatively experienced with motors but this will be the first time I have had to pull a head. I am not stupid, will take my time and will ask questions if not sure. No access to machine shops etc.

Basic plan to get her running again is replace the bent rods and hope the pistons are ok to reuse.

Replace any shot piston rings. Any pics of damaged rings would be helpful.

I will check pistons for damage and check the bores.

If bores scraped or damaged that will be that and off to the scrapyard.

I was going to wait until the oil pan was off to look up and see what damage I could see to the rods but I suppose I should just go ahead and pull the head. No benefits to delaying?

Anything else I need to be aware of when doing this?

Thanks

Barry.

Hello,

Man, those last two oil pan bolts are *****es. Had to hammer a 3/8ths socket onto the bolt head and use a wobble extension. This was after a lot of trying with a normal 10mm socket. Ball end allen key had rounded the centre. Anyhow, onwards and the oil pan is now removed and I am looking at the oil pick up. There is a part of this, the extended plastic surrounding it that seems a bit loose but seems normal?

I need to move forward now and I assume that my next step is to remove the oil pick up, set the engine to tdc, lock it in place and remove the timing belt and then the head? i will remove the turbo and manifold before removing head.

Guidance appreciated,

Barry

Those last two bolts are frustrating for sure. Why do you feel the need to remove the oil pickup? TDC, belt, turbo, intake and head yes, if it will line up at TDC.

Hi,

I can't get at the connecting rod bolts cleanly with the oil pick up in the way.?


On tdc, I found it hard to turn the engine with a small ratchet. She turned between 90degrees and 180 degrees. The engine did turn fully on the key with the force of the starter. Am I ok to turn her around with a breaker bar?

Barry

If you had a runaway as you suspect, the most likely damage will be to the head, if you’re lucky it’ll be just the head. You can check piston protrusion to verify if there is any further damage as in bent rods. I wouldn’t remove the crank and rods if I didn’t have to. Check the protrusion before pulling the rods, even though with numbers like you have (300) you probably have 3 bent rods maybe 4.

As far as turning the engine to TDC, when you pull the head you’ll easily be able to get the engine to where it belongs. Get it as close as possible and go from there. With the head off TDC is easy to find on the crank. Get it close on the head and you’ll be good.

What damage do you suspect will be done to the head?

Sorry if the question shows a level of ignorance..

I should also say that the engine was still full of oil.

It seems what burned was oil that was blown in from the intercooler and when that was gone she stopped.

Bent valves, spider cracked lifters. Again you won’t know if you even had collision until you pull the head and see the marks left by the valves on the piston heads, and fully inspect the lifters for cracks or domes.

As far as the compression at 300 or so goes I suppose it is possible your tester could be faulty. It certainly wouldn’t be the first one to give a low reading.

Ok, so not damage to the physical head itself like warpage etc?

Probably not but as long as the head is off you should check. You’ll shoot yourself if you put it all back together and something like that crops up later.

I’m assuming you’re in England, here in the states we would normally get a completely redone head from Franko6, you may want to check with Frans in the Netherlands.

His contact info should be in this link. He could probably get you a head or even an entire engine if you need it.

http://forums.tdiclub.com/showthread.php?t=445228&highlight=Frans

As for why it did it, the previous owner disconnected the turbo, likely cause it's done it before and they needed to keep driving it (to sell?). I'd say nothing for it but a complete evaluation of, top and bottom.

I assume as I cannot get the engine to TDC manually and I am pulling the cam and head, there is no point in worrying about timing for now apart from pinning the IP sprocket?

barrymurphy said:

I assume as I cannot get the engine to TDC manually and I am pulling the cam and head, there is no point in worrying about timing for now apart from pinning the IP sprocket?

Click to expand...

Correct.

Appreciate the excellent assistance. Sometimes its a quick pointer here or there that makes all the difference.

I have the cam cover off so I will see if I can see anything obvious on the lifters.

I will now proceed to pin the IP, remove the TB, remove manifold, turbo and then the head.

I checked the lifters,(cam still on),and they look perfect. I will give them a closer look when the cam is removed but on seeing nothing wrong i ventured underneath.

The oil pan has been off a few days and most oil has dripped off the engine.

I can turn the crank manually maybe one to one and a half full turns either way and doing this backwards and forwards i was able to look at the rods.

Number 2 is bent, number three looks like it is also and four might be as well. (Four looks straight but I am looking side on from an awkward angle). I cannot see number one with the oil pick up in the way.

So head will be coming off anyway and will check valves.
Is there a possibility the valves got away with it? seems unlikely?
Anything I need to be aware of when removing oil pick up and is there a particular process for this?

Is there a process for rod replacement on an alh?
My engine is an asv and I believe the only difference between the two is that the asv pistons are different in that they have oil channels.

If the engine stayed in time (I'd check just to know) the valves should be ok.
I suppose they could get bent if there was enough oil drawn in during the runaway.
You can see if they hit the pistons when you get the head off.
In the US I would send my unbent rods to Franko6 to match up with correct ones.
Hopefully you have a similar specialist available in the UK.

anything in particular I need to be aware of when removing the oil pick up?

no once only bolts etc etc

I have been offered an ALH engine that is of no use to someone for £50!

I assume rods and valves will fit in an ASV engine? but the pistons will not transfer?

Also any guides on removing and reinstalling the oil chain and tensioner?
Reading about disasters if tensioners break or not installed properly.

barrymurphy said:

I have been offered an ALH engine that is of no use to someone for £50!
I assume rods and valves will fit in an ASV engine? but the pistons will not transfer?
Also any guides on removing and reinstalling the oil chain and tensioner?
Reading about disasters if tensioners break or not installed properly.

Click to expand...

I would try to use the complete ALH if it is still together and a runner.

Is the block and head on an asv the same size as an alh, with the same fittings? I think they might be. The second hand engine will have been stripped for some parts but block and head are intact. I have no guarantees with its state only a scrap yards word for it. And i do not know the reason the car ended up in the scrapyard, it could have had its own runaway!

i wont really know till i open it up.

And I know the compression on my asv was excellent pre runaway so would trust it more. provided pistons and rings have not been damaged, should I not transfer rods?

thanks

See head from alh and the asv that had the runaway. Firstly the asv lifters, approx 4 of them not working. No surface damage but the spring inside is dead. So I assume valves working at speed killed them? The asv head has two valves that looks like heat discolouration.? Pistons look ok? Pulling rods in a while.



Sorry, how do I post pictures,?