General turbo question: one for those who know about the oil system

Yes If oil is getting passed the valve stem seals it will get burned off by the turbo. Also did you prime the turbo before starting the engine

 

Thanks for your input. Have you seen an apparently 'clean' input (no visible oil on port walls) to the exhaust turbine and an exit that
is awash with oil on the outer wall surfaces?
Is a minor visible trace of oil on the exhaust valve stems normal, or a sign that the stems are leaking badly. On a NA engine I wouldnt expect
any wet signs of oil in an exhaust port, ever.
Looking like head off is possibly next
(On line research though suggests these engine are fundamentally good for 200K..)
Regards
Jon

 

Perhaps it's CHRA ? (Centre Housing Rotating Assembly)

 

I would recommend taking or sending the turbo to be tested/checked. Turbo Technics make the vibration sorting rigs/vibration sorting and flow rigs that the industry use so they would be my first choice after using them recently to sort my own issues with another turbo remanufacturers 'efforts'.

 

There was another thread with a 1.8t same oil on turbo exhaust and turned out to be excessive crankcase pressure(bad plumbing for crankcase breather).
https://www.clubgti.com/forums/index.php?threads/1-8-t-turbo.290446/#post-2491289

 

thanks guys.
job has hit the wall, so rather rashly, went out and bought another engine/turbo today.
collect tomorrow.
surely with that many interchangeable spares I should be able to find the root cause. (turbo/head/bottom end etc)
I want it back on the road by end of next week
great stuff
Jon

 

Crankcase pressure not allowing the oil to gravity drain to the sump, I hadn't thought of that.
Would that not blow the dipstick out?
More thinking (by me) needed
thanks
Jon

 

That's why I was saying about trying to run it with the drain into a jug

 

This is relating to the 1.8T again I found it on passatworld.

 

Thanks, Tristan. I understood. The practicalities aren't that easy.
It doesnt really smoke at idle, only under load, at speed, especially on the over run.
The oil feed is a quarter inch line, which at 30psi is a huge amount of oil.
Things could go bad, quick, empty sump blah blah
I do appreciate the theory, but the practical, ahhhh
Regards
Jon

 

Understand, and I agree

 

Is there a restrictor in the oil feed line?

 

No, and that's 'standard' for a plain bush turbo, from what I have read.
My GTIR has a fancy roller bearing jobby, and an inline 1mm orifice to limit flow.
Honestly I am a bit tempted to restrict the flow to give the sealing a better chance, but it would be a bit 'suck it and see'
Jon

 

I am certain your new core is faulty ! Seals don’t stop oil on exhaust side hence leaking and smoking on the exhaust manifold when gets hot. I would drive it a bit to burn oil residue in the exhaust system…takes time !

 

'new' engine partially stripped, noted a few things.
Firstly, the restrictor to oil flow is effectively done by the banjo bolt which feeds the flexi oil supply line.
Oil arrives in the centre of a five mm bore and leave the bajo on two off 3mm holes
So the outlet CSA is smaller than the supply.
Think I'm going to try the 'new' turbo assembly on next..
At least now I have a spare cylinder head etc etc etc
Jon

 

The sealing ring on the turbine side isn't meant to totally seal all the oil, also it uses the exhaust back pressure to stop the oil migrating through this ring. Excessive crankcase pressure will stop the oil returning to sump correctly and could push it through this "seal".

The compressor side normally has soke form of oil scraper.

The turbo is designed to drain as quickly as it's supplied.

Some people have fitted pumps to the drain side but that shouldn't be needed for stock turbo. Same again with enlarged drain tube back to sump.

 

Great stuff, its obvious I need help here. I have bought a replacement engine/turbo. Used from 'scrappies' so
expectantations are minimal. Fitted the alternate turbo today, will report on first fire and first drive
R
Jon

 

Fitted second turbo and its fixed. Cant believe a new turbo cartridge failed? But apparently it has. Anyway its returned to the recon shop. Meantime im out 30hrs and ive ive bought a whole engine, now un needed, oh well

 

But what have you learned?

 

Most Recon shops use poor quality Chinese chra’s in their rebuilds, hence why they don’t hold for too long ! Most adjust the stop screw on VNT turbos so they are laggy and produce boost late in the rev range thus prolonging slow death and agony on poor turbos and engines ! I would get your money back from the turbo shop and get in touch with Adam Davidson at Pioneering Performance for a quality rebuild of your original turbocharger…pity you had to spend money to troubleshoot smoking engine but this is how you learn !