Marcel Burkett

I already have my suspicions , but I want to know what you guys think . here's what happens , when I rev. the motor past about 6000 rpm when the car is at a standstill or moving and let off the gas , then go back on I get a fairly large amount of blue smoke from my exhaust and over time I actually loose oil from my sump. I suspected the turbo and had it checked and rebuilt (there was a "massive imbalance" on it which was causing the turbine side oil seal to wear out , so it was rebuilt) , after this the problems' still there , my oil feed oririce size is 3/32" , if it were too big I suppose it would cause a constant smoke problem .
The motor pulls strong past 9000rpm , idles well and starts quite easily if hot or cold , my plugs come out with a brown/grey deposit on them indicating "good" combustion , I am now thinking oil "cage " rings and / or the oil seal O rings but my builder assures me that those things never cause problems and this guy is the "tini Ito" and I know he knows what he's talking about. I don't want to pull my engine unless I have to ( you know how much fun that is ) . :cry:

setzep

Take a look inside your down pipe and take a look inside your manifold after a smoking episode, compare and draw conclusion from there.

RICE RACING

I think its your turbo still bro.

I mean if the engine does not smoke much when cold, and it is only doing this on a gear change I feel it is drawing in oil from somewhere in the turbo.......... I will think about it some more but this is what my "gut" says right now ?

On your stationary "smoke" test the amount of oil your are describing will leave easily visable (oil traces) on your ground portions of the body of the spark plug, If its a nice sooty apperance whatever colour then its the turbo still. this is a good one to do from cold start up once engine is warm enough to rev up to genrate the smoke signals .

If the plugs are oily then check the charge pipe of the turbo too, it may be drwing in oil from the compressor seal area. This will be shown by oil in the intake charge plumbing.

RETed

What size AN lines are you using for the oil feed line?
If the oil feed line is too large, the turbo sucks too much oil from the rest of the engine, and you're basically oil starving your engine. If you have an oil pressure gauge, it'll read significantly lower than normal.

-Ted

Marcel Burkett

The oil feed line is a -6an size connected to a nozzle in which I've placed a webber carb jet with a 3/32" hole , my return line is -12an (5/8") , the air feed pipe (compressor discharge ) is very clean , no trace of oil or any type of residue.to totally eliminate the compressor I removed the comp. housing and revved out with the same result.
I did a test that points arrows to the engine to , here is what I did , I capped off the turbos oil supply , held the wheel frop spinning and had a friend start and rev the motor , there was smoke , but not as much though , so now I am even more confused as I am not sure where its coming from. When the turbo was rebuilt and rebalanced on the VSR I expect that any oil leaks of that magnitude would have been detected ?.

setzep

You got some ***** holding the wheel while having a friend rev the engine!

Witch is it, -12 or 5/8? -12 is 3/4 and 5/8 is -10. Either -10 or 12 should do the job though if it doesn't have any upwards slopes.

Mine would only smoke on a long decel with hot oil temps while on the freeway. What is your oil temp when this is happening?

RETed

Yeah, the -6AN is overkill. -3 or -4 at the largest.


-Ted

setzep

Doesn't matter if it's -6 if he has the restrictor at the turbo, he could have a -20 and it woulden't make a damn diference

Marcel Burkett

"The symptoms sound exactly like what you get with worn oil control rings/seals. I have only seen one engine that was excessivly bad. It did exactly the same thing. When I pulled it apart the the oil rings/seals were completely stuffed. However, it was an old 12A which had been sitting around for a few years and the rubber o-rings were hard and brittle.

Could possibly be the turbo. Maybe the oil pressure is just getting high enough at high revs to make it blow past. Don't know about all this 3/32" **** (stupid imperial system), but my turbo seems fine with a 2mm restrictor (although most people seem to use around 1.5mm). It's a long shot. Like you said, I'd expect that if it was too big the turbo would leak all the time."
This was posted on the other forum in response to the same question and this is what I also suspect (and fear ) , I was running the car for a few months before this with everything as is with no smoke at all , why ould my oil supply and feed now be the problem ? , I am also leaning towards the oil control ring "O" ring seals because they aren't original MAZDA pieces , they were part of a so called FELPRO (?) kit which was being sold by a guy down here , the price was good so I bought it , now I know why .

RETed

Sure it does, but if you can't understand why, I'm wasting my time trying to explain it.


-Ted

setzep

Enlighten me Ted.

Maxthe7man

with a fixed size metering hole, fixed size flow rate, the only thing that would change the flow rate, is pressure, and viscosity, which the the feed line will have no effect on whatsoever, but where did you pull the restrictor sizing from... I had a discussion with a guy at a turbo rebuilder about restrictors, and they advised against any kind of restriction in the oil line, they said if you need a restrictor, something is wrong with the turbo shaft seal itself, and restricting the oil, is not the answer. I just use 3/8 hydraulic line on a garrett with no smoking problems...
From the bad turbos Rx_7turbo2 had, when they leak, they leak all the time, and basically fill the exhaust to the brim with oil...
Does the smoke smell like oil? are you premixing, or using the omp?...Max

RICE RACING

Same basically, I never used any type of restrictor even with 110psi reg or system pressure. Never had a smokey turbo

setzep

Damnit Max I wanted to hear an explanation from Ted oh well..
I guess I can see where there would be a difference if the line from the engine was very long because then you'd have more pressure drop through it than a 1.5' line that most of use have.

Maxthe7man

The only time a line would cause a problem is in oil starvation where as if it was more restrictive than the restrictor, however that is opposite of what was being said, but like you said, you could have an 8" pipe feeding oil to the turbo, with a restictor, the same amount of oil would go through it as -4 an line...Max

setzep

Yeah, if there was a measurable delta P from the inlet of the hose/line to the outlet of it then it would aid the restrictor.

Marcel Burkett

Yes I do run premix , I removed my omp a long time ago , I am still not 100% convinced its the engine , I plan to do some more checks as soon as I get some time.

j9fd3s

iTrader: (3)

ususally if you rev it to 4-5k rpms when its cold and hold it there, and it smokes then its the rotor oil seals. the o rings will usually cause smoke at cold start, although these do/will overlap a bit.

when the rotor oil seals get really bad it will smoke if you let off over 7k (seems to need at least that much rpm until they really get bad)

mike