djseven

iTrader: (56)

What would be the symptoms of oil control ring failure if you had worn irons or just bad oil control rings. When would the car smoke, after boost when you let off throttle as the car is pulling a ton of vaccum, or would it smoke heavy at idle, under boost, high rpm? I have a car I am trying to diagnose at the moment and I think I have ruled the turbos out as they do not smoke underboost and the car doesnt really smoke on cold starts after sitting all night? Hoping someone with experience with this will chime in.

If I boost the car, then let off throttle it takes about 3-5 seconds before a big cloud of smoke comes barrelling out of the exhaust pipe. The car does not smoke under boost even during a long pull. It is only after throttle is released and still take about 3-5 seconds before the smoke appears. Every car I have ever had with blown twins would smoke while under boost?

Thanks in advance.

djseven

iTrader: (56)

Also note, that when you let off the throttle while at 30-40mph when not in boost, you will still get 23-25in of vaccum. When doing that it does not smoke, only after the car has been in boost, which makes me think its the turbos. However, I just swithched the turbos out for a "Known good set"(said by another forum member) and the car does the same exact same thing.

Has anyone else who had failing turbos only have them smoke after you let off the throttle after boosting?

Snack

i don't think its failing turbos... does the car have some sort of fuel management? it could be running rich because of a tune. ive seen many cars smoke after hitting boost because of rich tunes

djseven

iTrader: (56)

Its definately oil without a doubt. Im just trying to figure out for sure if it is the twins or the oil control rings/irons.

DaveW

Could the PCV system be causing this? Do you still have the stock setup?

djseven

iTrader: (56)

Full non-seq with everything deleted that can be.

DaveW

What do you have? An oil catch can, or what?

djseven

iTrader: (56)

Sorry I should have been more clear, i didnt pay attention to what you were asking. I still have the pcv valve in place and have replaced it with another known for sure good one.

dgeesaman

iTrader: (7)

Maybe looking for fuel dilution into the oil would tell something. Unfortunately I have no idea what you'd compare it against, since I'm sure there's no agreed 'normal' amount of fuel accumulation and you don't have past information.

Dave

Six Rotors

iTrader: (17)

Usually the O rings in the rotor oil seal age with heat etc.You see big smoke on cold start due to oil leaking down into the rotor housing,and depending how bad the O rings are,you would see constant smoke across the rev range.Oil consumption would be high.

Andrew.

iTrader: (4)

Smoke at high RPM's from what I've heard is a usual indicator of oil control rings starting to go out.

djseven

iTrader: (56)

Im pretty sure I have figured it out, I must have some type of restriction somewhere in the PCV setup. I removed the oil filler neck cap and the car doesnt seem to smoke anymore. However, it is dark and is difficult to judge using street lamps on back roads. I will update the thread tomorrow but I am somewhat confident it is in the PCV system. Thanks to DaveW for making me think to look back at that.

David

DaveW

Hope correcting the PCV function fixes it. That was just a guess based on some things I've seen in the past on other cars (not my FD).

Dave

djseven

iTrader: (56)

Ive never had a problem like this before in 50+fds so I really appreciate the idea you gave me. Im hoping I have it fixed now.

David

Herblenny

iTrader: (13)

David,

Here is what I've experienced regarding oil control ring..

I bought a car 3-4 years ago that smoked like hell! When I say smoked like hell, couple of mins after you crank the car, you couldn't see the car no more (i sound southern.. LOL!).

I was hoping it was the turbo but when I took the turbos off, there was ton of oil everywhere.. after I took the manifold off, I could see the oil inside the engine and all around the manifold. When the engine was pulled and broken down, it sure was the oil control rings...

fd0

iTrader: (8)

I had the same symptoms but opening the oil cap didn't help for me. It also didn't help that it was my first engine that I tried rebuilding too as well as not really looking at the turbos for any leaks.

Let us definitely know what comes with this, this would give me more peace of mind where I might have screwed my build up.

gracer7-rx7

iTrader: (16)

Dave,

Could you elaborate please?

Thanks.

Andrew.

iTrader: (4)

Oh, that reminds me. About 4 years ago or so I bought an engine from my friend that was excessively smoking (he even got a ticket, haha), when I tore it apart, the oil control ring SPRING was broken into about 3 pieces.

dgeesaman

iTrader: (7)

As I understand it, the so-called fuel dilution in the oil comes directly from combustion gasses / unburnt fuel pushing past the oil seals. So a bad oil seal would show much more rapid accumulation and viscosity loss than in a normal engine. A theory - that's all.

Dave

mono4lamar

iTrader: (32)

I know it may sound stupid but... are you sure you don't have the pcv valve in backwards? I did this and it smoked like a SOB on decel

djseven

iTrader: (56)

I deleted the PCV and routed the line back over to the Primary Turbo Inlet and capped the other nipple on teh oil filler neck. It solved the problems. Car no longer smokes at any time.

Thanks again to DaveW and everyone else who made suggestions.

DaveW

You're welcome. Glad I could help!

I had a Passat 1.8T that had a PCV problem. It had a bad check valve that was letting turbo pressure pressurize the crankcase, leading to all sorts of (mostly blown or leaking gaskets) problems, and I thought that might relate to your oil-smoke issue.

Dave

RotaryEvolution

iTrader: (30)

guess i'm too late, it definitely sounded like the added boost is forcing the PCV valve shut for too long and building up too much cranckase pressure. another solution is just to put an oil catch can on the engine though the FD doesn't have much room in the engine bay to place one if you have the P/S and A/C still.. i'm not a huge fan of the stock PCV system once you start pushing over 300WHP, after that point it's just hit or miss if you are going to have blowby issues or not.

fd0

iTrader: (8)

Great find. I'm definitely subscribing to this just in case this happens to me again(hopefully never but you never know).

grimple1

iTrader: (1)

I'm having similar problems. I'm hoping it's not oil control rings. I just had the stupid engine rebuilt. I thought it was leaky turbo but with a new turbo the problem remains.

I looked at my pcv setup and the line off the throttle body has been caped along with the top nipple on the oil filler neck with a catch can attached to the bottom nipple. The car has not been boosted since it's been rebuilt and never more than 3-4k rpms. Currently it's a N/A FD

PCV or am I in bigger trouble? Any help would be great.

Here's what's been "fixed"
Engine rebuild 2k ago (it's been doing it off and on the entire time)
New turbo w/ SS oil lines.

Any help?