12HT oil in tailpipe & CT26 blown oil seal

Paco

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Nov 29, 2006
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292
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Oregon
Hey all 12HT and CT26 gurus - need some help with diagnosing turbo problems.

Background:
88 LHD stock HJ61 with 12HT and CT26 with 314,000 km
Turbo oil seal was blown - rebuilt in 2019 at 296,000 km
No boost or EGT gauges

After driving back from SAS this summer up some long hot grades pretty sure I ran some high temps and now the turbo is making a whining (non-turbo) noise under load. Also have excessive smoke (white/blue) and what seems like a slight loss of power. Stock temp gauge went slightly above the next to last mark but returned to mid-point pretty quickly.

I pulled off the air intake and the compressor blades all seem intact and no play in the bearings. Looked at the blades on the exhaust side and they are also all intact.

I have always had smoke on start-up until warm. No smoke on idle but visible smoke on acceleration - pretty common 12HT as far as what I have read. Currently going through a quart of oil about every 4 or 5 tanks.

Next steps:
Install boost gauge - done and showing a max boost of 7.5 psi
Install EGT gauge
Replace exhaust - Completed last weekend. Installed new 3" exhaust and dump pipe from Factory Direct 4x4 Exhaust. Fit was great!!
Rebuild CT26 again (ugh!) or replace with GTurbo vortex green.
Engine work???

Symptoms:
Oil dripping from bottom of turbo
Oil at inlet pipe/turbo connection
Oil in vacuum line on inlet side at boost gauge connection
Oil in tailpipe - after installing new exhaust drove 20 min and then wiped oil from tailpipe.
Smoke as mentioned above
Head gasket? - no milkshake oil on top or in dipstick and no noticeable loss of water.

Questions:
Is the oil pooling in the turbo from the blown turbo seal or something in the engine? Valve seals? Piston rings?
How long should a rebuilt CT26 last?
Would wear in the CT26 housing cause the oil seal to fail again after my last rebuild?
Is excessive crank case pressure blowing out the turbo oil seal? If so is a catch can a good idea? Seems like this does not address the root problem and would only be a temporary issue.
What is the best way to go about diagnosing what is going on with either the turbo or the engine?

I am leaning towards replacing the CT26 with a GTurbo, but if there are other issues causing the excessive oil would need to take care of those first.

Any and all thoughts would be greatly appreciated. @roma042987 I know you are very busy, but being the 12HT wizard that you are wondering if you have any ideas?

Cheers
 
Joined
May 15, 2005
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9,523
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Ladysmith
Check your head gasket. The crankcase vent into the air inlet if it hasn’t been cleaned causes oil to leak
from bottom of turbo. But the white smoke and high heat makes me think take a look at coolant,
ensure no oil. Drain oil, check for no coolant. Get a flashlight and looks all around the perimeter
of the head gasket.
 

Paco

SILVER Star
Joined
Nov 29, 2006
Messages
292
Location
Oregon
Thanks @cruiserpilot will check the crankcase vent - that makes a lot of sense given where I am seeing oil.
Per the FSM white smoke and excessive oil consumption are a sign of a faulty turbo seal. It also lists carbon deposits on the turbo wheel as well.

For reference here is a shot of the turbine wheel which looks pretty dark:

IMG_7316.JPG


For comparison here is the compressor side:

IMG_7245 (1).jpeg


And a shot of the oil dripping from the bottom:

IMG_7314.jpeg


After posting this I have been doing some more research on catch cans and they seem to solve the oil in the intake issue.
@cruiserpilot I know you are running one on your 12HT. Can you post pictures of your install?
HPD out of Australia is also highly rated (spendy) but it seems there are also less expensive options on Ebay.

I just checked coolant level again and it is full with no sign of any loss. Will check around the head gasket to see if there is anything there.

Thanks!
 
Joined
May 15, 2005
Messages
9,523
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Ladysmith
@cruiserpilot I know you are running one on your 12HT. Can you post pictures of your install?
Fairly simple. I went with clear tube just to keep an eye on the accumulation. The Provent 200 has its own
proprietary filters that have a fairly long replacement schedule. This was rated 1 or 2 on several comparison
reports I studied. I only just heard of the HPD, twice the price of the Provent but with no filters - cheaper
over the years. Decision of which to use is yours.
Heres a couple of install pics. I relocated my radiator overflow to the air cleaner housing. I can still
get by it to prime the fuel pump if needed.
All these catch cans are quite large, so amending locations to create real estate for it is a bit of a pain.
E322F2E6-A2E6-4696-A18B-961879AFD4B3.jpeg
7310EE3F-03DF-41CB-B593-CC23F54A0928.jpeg
 
Joined
Jun 10, 2007
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Kiwiland
That's what the turbo does when your engine has too much blowby. Do a compression test.

Where does your provent drain to? I had a provent suck oil out my sump and feed it into the engine. Blowing my head-gasket. IMO one of the worst purchases I've ever made. But I don't see too much oil pooling in those hoses.
 

Paco

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Joined
Nov 29, 2006
Messages
292
Location
Oregon
A compression check is in the works this week. Also pulled the trigger and ordered a catch can from HPD.
 

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