300tdi turbo - any hope of repair?

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julianf

julianf

Well-Known Member
Posts
2,305
Location
Devon, UK
Ok, so classic "running when last run" -

Disco was parked up for about 18 months. Vermin nested in the air filter. I assume they urinated down the inlet duct and now I have this -


IMG_20220608_163731303 (1).jpg


The engine still runs, just not above 2000rpm.

Is this a scrapper, or do things like this come back from the dead without me having to re-mortgage the house?

Thank you.
 
Best to strip it down and check if a new CHRA is an option first as depending how bad the corrosion is on the compressor housing, if its too corroded then it may as well be a whole new turbo
 
Right, so ive been, periodically, soaking this in GT85 (wd40-a-like) and put a socket on it today for the first time, and it freed up almost instantly. So little force that, initially, i figured the socket must not be in place.

The inlet vanes now spin without any friction. Almost (i cant see, so i cant be sure) feel like they carry on spinning after a bit of a flick.

So i revved it up, and....

intercooler to inlet manifold tube just collapses in on itself, just like before : (

...even with the air filter to turbo tube off the back of the turbo, so its not a restriction there.


Engine idles and drives fine, just as soon as it picks up revs, it collapses the tube to the inlet manifold.


So, whats happening here?

When people pull the turbos off these for series conversions, im guessing they make no real fuel adjusments? What i mean is, if the turbo wasnt on there at all (ie no boost, just naturally aspirated) then there would be no collapsing of the ducting. But then it wouldnt have the restriction of the intercooler and (possibly) non spinning turbo, i guess.

Or the exhaust side could be blocked?

I cant think that the (free spinning) inlet side has become detatched from the exhaust impeller. I assume the exhaust impeller is spinning, but maybe its not. Again, all feels frictionless by hand.

(i have another turbo that ive been dousing in a similar way that got left on an engine exposed to the rain - that one is also free, but has constant friction the whole way around - this one isnt a bit like that)

I dont really care too much about this setup, as its just a spare in a scrapper disco, but its irritating me that i cant work it out.



Im thinking -

take the turbo to intercooler pipe off and see what happens (to rule out intercooler heavy restriction) or maybe just the intercooler to manifold pipe, and see how it revs then
if its good, get a friend or mirror or somthing to look at the turbo and see if its actually spinning
and then go from there?

sound like a plan?
 
REKT said:
I'm wondering if the pipe itself has delaminated and it causing a blockage which it making it collapse, try inspecting the pipe first
Click to expand...

Anything could be the case, but the intercooler to manifold pipe should be at greater than atmospheric at that point, i think.

Ill take it off and have a look though - these things dont always make perfect sense!

Thank you.
 
Turbo does spin fine - if i spin it by hand, and lightly touch the centre as i release, i can feel it spinning down (ie it carries on with its own momentum for a bit, so there's certainly no excessive friction)

But, latest test, and results -

Took, off the intercooler to manifold hose at the manifild end, and swivelled it round so i could get my hand over the hose end and reach the IP at the same time.

If i build the revs, there is clear boost from the turbo, until a point. At that point, it makes some odd sound, not unlike a boy racers dump valve, and the boost drops to zero, even as the revs increase. (i know nothing at all about petrol engines btw)

Theres no real play in the impeller, but its as if the turbo operates fine, until a certain RPM, and then it binds up entirely.

Could this be somthing to do with the waste gate?

In driving, i guess its good for about 20mph, but nothing much more.

Its a hot day today, but the engine started on very first revolution - so the rest of the thing isnt in bad nick.
 
Had a 19J I replaced the turbo with a cheapy junk yard special. Had a very small piece broken on one vain in the turbo, freely spun in the housing, otherwise looked fine all around. At higher RPMs it dropped power, would not make speed. After carefully looking at the turbo again I could see a shinny spot where it might have been binding up inside the housing. I though it was a balance issue at high RPMs. Replaced the thing and all was well.. Maybe that rodent pee took some metal with it.
 
julianf said:
Turbo does spin fine - if i spin it by hand, and lightly touch the centre as i release, i can feel it spinning down (ie it carries on with its own momentum for a bit, so there's certainly no excessive friction)

But, latest test, and results -

Took, off the intercooler to manifold hose at the manifild end, and swivelled it round so i could get my hand over the hose end and reach the IP at the same time.

If i build the revs, there is clear boost from the turbo, until a point. At that point, it makes some odd sound, not unlike a boy racers dump valve, and the boost drops to zero, even as the revs increase. (i know nothing at all about petrol engines btw)

Theres no real play in the impeller, but its as if the turbo operates fine, until a certain RPM, and then it binds up entirely.

Could this be somthing to do with the waste gate?

In driving, i guess its good for about 20mph, but nothing much more.

Its a hot day today, but the engine started on very first revolution - so the rest of the thing isnt in bad nick.
Click to expand...


As you have stored the turbos where they have gotten wet, maybe they have corroded the casing internally, and when it warms up they expand and stall the turbine?

Boats have issues with seized turbos, even if they free up it never ends well.
 
I was chatting elsewhere about this also, and have been convinced to change the hoses. I don't know if it will make any difference at all, but we are talking a bit over a tenner for the set of three. I've ordered them but they're not here yet.

Someone suggested that if the one at the bottom of the intercooler was delaminating and there was a flap on the inside that blew shut like a valve that would give the symptoms. I'm not sure but I figured I'd give it a go.

Ill report back when I've changed them.

Thank you.

Ps. Having a proper look at the vanes involves taking the thing off. I've been using the selfie mode on my camera phone so far, but it's not ideal. I guess I could try with a mirror.
 
miktdish said:
I have a solution .....

View attachment 269940 View attachment 269941 View attachment 269942 View attachment 269943 View attachment 269944

Done less than 1200 miles as I replaced it with a VNT in November 2021
Set @ 16psi

View attachment 269945


Would like circa £285 .... inc delivery UK
Click to expand...
Wow, those pictures are great! That engine bay is soooo clean. I don't even own a 300Tdi but I want to blow those shots up for "Man Art" in my "Hookah and Booze drinking" section of the garage-cave. :) Good on you!
 
julianf said:
I have another known good turbo and manifold on the shelf. That's not the issue. The issue is that i want to fix the setup that's on the engine currently.
Click to expand...

Then you need to take it off, put it on the bench, dismantle it, check everythings OK and put it back together.
Seals etc are easy to get it's balancing the impellors and core thats the difficult bit. Then you'll need a way of measuring the uplift.
 
miktdish said:
@julianf How are you getting on ?
Click to expand...

Still waiting on parts. I'm only trying to fix this turbo issue as "somthing to do" as the engine is, basically, redundant / a spare (in a rough old disco that I've been keeping whilst getting my 110 sorted)

Sadly, whilst I'm in no rush for these bits, my 110 isn't going anywhere quick whilst it has no working lift pump (also in the same order).

I know I could steal the one off the disco, but, in my experience, you only have to look at them and they break, so I'd rather not mess with the one on the disco whilst it's still working!
 
Long overdue update to this -

I ordered all the hoses from the turbo to the intercooler then to the manifold, as someone suggested that delaminating would cause the issue, and they were cheap enough.

Changed them yesterday. No change in operation at all.

To recap -

If i have it setup as standard, it runs fine, up until a certain rev range, when the turbo makes an odd noise, and the old hoses would collapse, and the engine would hiccup and smoke.
If i disconnect the intercooler to maifold hose, so it runs naturally aspirated, the engine revs up fine, and the turbo seems to be shifting a fair bit of air, until the same point, where the turbo, again, makes the odd noise. But, in this case, the engine does not hiccup in the same way, as there is no restriction.

Someone else said that it would be the waste gate not closing, but wouldnt this cause overboost, rather than underboost?
 
julianf said:
Long overdue update to this -

I ordered all the hoses from the turbo to the intercooler then to the manifold, as someone suggested that delaminating would cause the issue, and they were cheap enough.

Changed them yesterday. No change in operation at all.

To recap -

If i have it setup as standard, it runs fine, up until a certain rev range, when the turbo makes an odd noise, and the old hoses would collapse, and the engine would hiccup and smoke.
If i disconnect the intercooler to maifold hose, so it runs naturally aspirated, the engine revs up fine, and the turbo seems to be shifting a fair bit of air, until the same point, where the turbo, again, makes the odd noise. But, in this case, the engine does not hiccup in the same way, as there is no restriction.

Someone else said that it would be the waste gate not closing, but wouldnt this cause overboost, rather than underboost?
Click to expand...

Waste gate not closing will cause under boost, have you set up the actuator properly.
Crankcase vent issue ??
 
kevstar said:
have you set up the actuator properly.
Click to expand...

Was running when last run... : )

So its going to be something jammed up or gnawed through rather than improperly set up.

I cant think its crank case vent? That would force oil through the turbo seals and it would get the whole "burning tyres" smell about it, which its not doing. Mind you, im not getting it hot, but, all the same, ive had that issue before, and i dont think this is the same.

kevstar said:
Waste gate not closing will cause under boost
Click to expand...

Let me get a grip on this... At low rpm the gate is, what, closed, so the flow is directed over the impeller? And then the actuator opens it, to bypass?

If its jammed up it would have done it in the "direct most over the vanes" mode (be that open or closed, i may have got my terminology wrong) and then as the rpm rises, someone said that, if the gate doesnt back off the flow, the turbo can go "supersonic" where its not actually then producing boost any more, even though its spinning real quick.

Does that make any sense?

If it was a bit more accessible, id just grab it and give it a wobble, but its hard to get a grip on the lever.
 
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