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TDI Power Enhancements Discussions about increasing the power of your TDI engine. i.e. chips, injectors, powerboxes, clutches, etc. Handling, suspensions, wheels, type discussion should be put into the "Upgrades (non TDI Engine related)" forum. Non TDI vehicle related postings will be moved or removed. Please note the Performance Disclaimer.

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Old June 18th, 2003, 21:51   #1
RogueTDI
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Default Soot, Hot Shutdowns, and Turbo Bearing Coking

Well, I started using a good synthetic oil in part for the increased resistance to turbo bearing coking and failure.

Just did a really hot shutdown, and I just realized - wouldnt the soot in the oil of our TDIs coke bearings up just as well as the deposits left behind by conventional oil?

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Old June 19th, 2003, 05:57   #2
GoFaster
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Default Soot, Hot Shutdowns, and Turbo Bearing Coking

No. It's not the soot that does the coking - it's breakdown of the oil itself. No worries. I've never heard of a TDI coking its turbo as long as synthetic oil was being used.
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Old June 19th, 2003, 09:13   #3
runonbeer
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Default Soot, Hot Shutdowns, and Turbo Bearing Coking

KERMA reported that he was going to use mickey's VNT 17 but had to replace the bearing due to coking. mickey runs amsoil. he also lives in the mountains (steep hills) at high altitude (thin air).
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Old June 19th, 2003, 14:10   #4
RogueTDI
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Default Soot, Hot Shutdowns, and Turbo Bearing Coking

Quote:
No. It's not the soot that does the coking - it's breakdown of the oil itself. No worries. I've never heard of a TDI coking its turbo as long as synthetic oil was being used.
Well, what is the residue composed of anyway? I imagine that even if all of the constituents in a high quality synthetic oil were boiled away on a red-hot turbo shut down, the soot might still bond to the bearing metals. I am sure the coking process is different with a conventional oil, but why wouldnt the soot bond to the metals under high temp conditions? I'm no expert, just thinking of possibilities.
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Old June 19th, 2003, 20:15   #5
KERMA
 
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Default Soot, Hot Shutdowns, and Turbo Bearing Coking

Quote:
KERMA reported that he was going to use mickey's VNT 17 but had to replace the bearing due to coking. mickey runs amsoil. he also lives in the mountains (steep hills) at high altitude (thin air).
Yes you are correct.

The oil seal was bad, so I sent the turbo to its daddy in Texas (Robert at Forced Performance) so he could go through it. He said the bearing was so coked that the shaft hardly turned at all, and the shaft itself is discolored from the rubbing. Stupid Amsoil!

Talked with Mickey later, he said he ROUTINELY pegged his EGT gage for MILES going up Parley's at 100+ on his commute. That's 1650F plus, folks. His oil temps exceeded 280 for extended intervals also. So it's not Amsoil fault after all, I don't think it was designed to be boiled... I tell ya, that guy should get a job testing stuff trying to break it, he sure is good at it! If Mickey can't break it, then, hell, it's probably over-engineered anyway, too expensive to produce.

Remember 10% soot levels before he re-torque his racewares, too. Probably didn't help.
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Old June 21st, 2003, 12:43   #6
RogueTDI
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Default Soot, Hot Shutdowns, and Turbo Bearing Coking

So, KERMA. I am assuming that the Amsoil is not causing the coking. Would I be wrong? Whether you like it or hate it, I am pretty sure Amsoil is a true synthetic and would probably not leave coking residues in high temperature use. I could be wrong, but if we could rule out the oil, then there is nothing left BUT the soot.
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Old June 21st, 2003, 15:54   #7
weedeater
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Default Soot, Hot Shutdowns, and Turbo Bearing Coking

Excuse me, 1650F????

That'll coke anything!!
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Old June 21st, 2003, 17:20   #8
RogueTDI
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Default Soot, Hot Shutdowns, and Turbo Bearing Coking

So, maybe I just dont know my stuff here.

Will a good synthetic leave residues when boiled away? Will it become chemically unstable and react at temps of 1650F?

Gasser turbos run hotter than that I am guessing, and synthetic is supposed to help them with bearing coking issues. I wouldnt think that 1650F will "coke anything."

BTW, that temp seems a little hard to believe. I am guessing he has lots of mods to get those temps out of a diesel engine.
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Old June 22nd, 2003, 05:18   #9
therabbittree
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Default Soot, Hot Shutdowns, and Turbo Bearing Coking

the part that is really bad is not so much the egt temp but the fact that he held it at 1650 plus for MILES!!!! normally your right foot controls your egts ..if you see the gauge hit 1300-1500 or so you let off a little and definately don't hold it for more then say 20secs...and this is with a pre turbo egt setup....no matter what oil you use you should wait to shut the engine off untill the egts come down to 300 degrees...above that is a little too hot to let the turbo sit with out oil pumping through it to cool it...coking can happen with any oil snythetic or mineral.. just much less protection or safety window if you don't use synthetic etc...
later
Deo
\x/ hillfolk!
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