Oil control rings shot?
 

My FC is giving off an oil smoke screen under certain conditions, and I suspect the oil control rings may be the culprit. Before I even consider cracking open the keg, I wanted to get some confirmation from the forum. Here’s the pertinent info about the car, symptoms and what I’ve tested so far to draw my conclusions:

Basic facts:
• ’89 T2, running a Hayes rotary crate rebuild motor that I installed in 1999, that now has almost 60K miles on it. Runs very strong, good compression & starts every time. Not a daily driver, but weather permitting I’ll take it for a romp every weekend.

• Turbo is a BNR Stage 1 rebuild, that I installed in early 2011, it now has about 5~6K miles on it.

• Installed the RA-OMP adapter to run premix thru the stock OMP system last winter, have about 3000 miles with that setup.

Symptoms:
• While accelerating moderately hard, I’ve seen smoke out my rear view mirror start to become noticeable at around 5K RPMs and up. It’s definitely oil smoke - bluish in color with that acrid stink. If I abruptly let off the gas, while keeping the car in same gear to keep the revs up, the smoke cloud gets VERY dense. So the smoking seems to get worse while decelerating or holding a steady speed at a high RPM (off boost) that it is while accelerating/boosting.

• If the car sits for more than a few days between starts, on the next startup I’ll get a short lived cloud of oil smoke as the car idles. Smoke is gone in less than 10~30 seconds, a bit longer if the car hasn’t been run in weeks. I think this particular symptom has something to do with my RA-OMP adapter setup, as I’ve noticed the level in my premix tank drops slightly even when the car just sits in the garage unused for a few weeks – I think some premix is gravity feeds itself into the keg, and that oil gets burnt up on 1st start.

Things I’ve tested/checked out so far:
• Had a friend follow me on a few runs to confirm what I was seeing out the rearview mirror – no doubts there, symptoms above are confirmed.

• Opened up the intercooler piping to look for evidence of oil. IC piping & rubber elbows had some oily film, but no pooling of oil anywhere. Not enough here in my judgment to convince me that oil is getting sucked in via the turbo compressor side, given how long it’s been since I last cracked open the IC piping and the # of miles I put on it since then.

• No visible leaks anywhere, oil or otherwise.

• Tested the Purge Valve/PCV per the FSM procedures, and it is working properly.

• Ran the test on Ted’s FC3SPro website where you rev the car up to 3~4K RPMs in neutral and hold it at that RPM for 10~15 seconds or so to see if it smokes. I had no smoke visible up to 4K RPMs, even after holding it there for 30+ seconds. No smoke when I let off the gas either. Repeated this same test, but with incrementally higher RPMs each time, and held it there for about 15 seconds. Starting at about 5200 RPMs, the smoke came back after about 10~15 seconds of holding it at that RPM. At higher RPMs, the smoke cloud just gets thicker, and it becomes visible earlier in the “hold” period.

So what do you guys think? Anything I missed here?

Pull the spark plugs...
Does the plugs look like excessive oil?

If it doesn't, it sounds like turbo turbine seal is bad...


-Ted

Good idea. I'm taking off work starting Wed, so I'll pull the plugs then and take a look/snap some pictures. IIRC, plugs last went in last spring before DGRR, so they have about 3~4K miles on them now.

Try pulling your downpipe and check the color of the turbine. Brown/tan is normal, an off white is indicative of oil burning from the turbine seals.

Increased smoke on deceleration is a classic symptom of blown oil control rings. I'm not very knowledgeable in regards to turbos though, so there may be something related to that whole system.

If it is the oil control rings, you can get very good results with Lucas Heavy Duty Oil Stabilizer. My old 12a was leaving a smoke screen, which was 95% alleviated by running a quart of the Lucas in the oil. Put about 30k miles on that motor until it coughed up an apex seal at 213,000 miles.

I still use Lucas in my current motor just as a preventive measure...



.

Well here's a picture of the plugs. No evidence of wet oil anywhere when I pulled them. Probably hard to tell in these pictures, but color of deposits is a black to brownish and have a sooty texture to them - running my finger over them it feels like 1000 grit sandpaper, and some of the carbon residue transfers easily to my fingers. What do you guys think? Probably should pull the DP to take a peek at the turbo turbine wheel next.

http://www.rotarycarclub.com/rotary_...1&d=1353515572

Spark plugs looks pretty good...

Blame is starting to shift toward the turbo turbine section.

Just to eliminate the easy stuff...
Stock turbo drain assembly?
If it's been replaced, what size fittings and hose?
Relocated drain point back into sump?

PCV system still intact?


-Ted

That's what I thought about the plugs too, pretty normal wear & tear.
PCV is fully intact and verified to work per FSM procedure. I did have to modify the stock turbo drain to solve an interference problem with my RA OMP adapter. It uses -10 hose & fittings, retains the stock return point on the front cover and is routed almost the same as stock. Compared to stock, it takes a bit of an arc away from the block, but the plumbing has a downward slope the whole way back to the front cover. This thread has a photo of it, see post #6

http://www.rotarycarclub.com/rotary_...ad.php?t=14945

Resurrecting my old post. Those of you who were behind me a DGRR this year were treated to the smoke screen. I finally got around to pulling the DP and taking a look at the turbine wheel...

Here's some pictures, I'm thinking shot turbine seals now, what do you guys think? Definitely white/off-white color deposits.

http://www.rotarycarclub.com/rotary_...1&d=1372715987

http://www.rotarycarclub.com/rotary_...1&d=1372715987

http://www.rotarycarclub.com/rotary_...1&d=1372715987

nm, clipped wheel and angle made it look odd.

check the shaft for thrust play and excessive side to side play indicating worn shaft bearings and/or worn thrust plate.

Bryan also removes the oil restrictor to the compressor assembly which sometimes causes blowby issues even in the turbine section. you can run a restrictor to the oil feed if you have any oil pressure modifications or lacking crankcase breathers.

Sorry for the crappy pictures, was tough to get a good focused shot from laying on my back under the car. I checked the shaft for play by hand, no thrust (end-to-end) or side-to-side play that I can feel, but the shaft rotates freely without any binding.

Didn't know Bryan removes the oil restrictor; would that be an issue with a stock oil system? I have no oil pressure mods. Also, the car is using the stock crankcase ventilation system, which was tested per the FSM and found to be working.

the stock crankcase vent system is fine for stock boost levels, beyond 10 psi even on a hybrid i would recommend opening it up to vent to atmosphere via a breather tank.

I still have the stock ECU (w/Rtek 2.x mod) controlling boost, so boost pressures are limited to S5T2 stock levels - I never see more than 8~8.5 psi in the Rtek data logs or on the boost gauge. And with the BNR waste gate porting, this setup is well controlled, it never spikes or creeps upward beyond those levels.

Given that, I'm not sure what benefit I'd get from switching to a catch can/breather tank crankcase vent, other than keeping a little oil film out of the intake plumbing & IC.

There's no reason to be running some catchment system on a street car, no matter how much power or boost you're running.
You just can't run the car hard enough on the street to see an advantage to such system.
Catch cans can cause more mess in the engine bay due to it's design...

The pics of the turbine wheel aren't detailed enough to show any obvious problems...
The color is actually right for a normally running engine.
Maybe you can get some black crud to fall out of the turbine housing by tapping on it with a hammer?
Most likely you have blow-by from the turbine compression ring, but it may not be obvious until you pull the entire turbo apart...


-Ted

Yeah, I agree.

Wish I thought of the tapping it with a hammer trick while the DP was still off :banghead: