gio64

iTrader: (1)

Hi everyone.
I have changed my twins because the secondary was soaked with oil.
The used set I installed seems to be fine.

The car is still using too much oil however the car doesn't seem to smoke under boost any longer. There is just a bit of smoke at startup when dead cold, but it fades away within a minute. I really don't see how this would cause the car to ingest so much oil.
I read about the check valves in the vacuum lines going into the primary intake elbow and the possible failure leading to boost putting oil back in the turbos...
I have a question: would it be OK to simply disconnect the two vacuum lines for testing purposes and drive like that for a few days?
I understand that these lines are supposed to get filtered air, to the OMP injectors (I hope I got this right) but I was wondering if this would cause a problem in case I try to troubleshoot for a short time.
Also, forgive my non expert question, are the valves inside of the vacuum lines (in case I need to replace), or are they located elsewhere?
Please help,
Giovanni

DaleClark

iTrader: (55)

The check valves are built into the oil injectors themselves. I'm really not sure what happens if those check valves are bad.

The vacuum lines from the check valves run to the primary turbo inlet, which is never under vacuum or boost. It's basically just after the air filter. Mazda ran it like that since you can't vent anything to atmosphere that could potentially have oil or gas vapors.

Running it open to atmosphere should be no problem, short term or long term.

Next place to check is the PCV valve. Stock, most FD's have a plastic PCV valve between the top nipple on the oil fill neck and the upper intake manifold. In '95, they redesigned it - cap off the one nipple on the oil fill neck and the nipple on the intake manifold. Not only does this make the car far easier to work on, but eliminates a frequent point of failure, and it's a Mazda-approved method as the '95s are like this. The nipple on the oil fill neck that points down needs to remain hooked up - it goes to the rat's nest then to the primary turbo inlet.

Dale

dgeesaman

iTrader: (7)

I would add premix if you're going to try anything like that. It can't hurt.

Another option is to make up some really simple catch cans and connect them in-line. Then if oil is running through the lines you'll see it collecting in the can.

Dave

gio64

iTrader: (1)

Thanks guys,
I appreciate it.

I was reading a thread and it said that if the check valves are bad, under boost they pressurize those lines and the oil gets blown back into the intake tract as the valve is allowing flow both ways.

I asked the question because if I can simply disconnect them without causing any trouble, I can quickly find out whether or not they are a problem, without taking anything apart.

I read that some people (especially those with single turbo setups) remove them and use unfiltered air. I also read that this is however not good, as it causes in the long run dirty air to go where it is not supposed to go.

As for the pcv valve, Dale, thank you for the suggestion, however that was the first thing I severed when I started to track down this problem. It is capped while the other line you mention is still intact. If I understood this properly, there needs to be some negative pressure in there to help the flow of the oil back in (please don't flame me if this is not the case). At that time, I read that if the PCV valve goes bad, it allows boost to pressurize the oil, hence the blowing back to the intake. In any case, the PCV line is capped at the oil filler neck.
Thank you, and if anyone else wants to chip in, I appreciate all the insight
Giovanni

gio64

iTrader: (1)

Hi again.
After re-reading some stuff, I realized that driving with those vacuum lines open won't keep the oil from coming out in the wrong place, if that's indeed what the problem is.
However, if I were to check the vacuum lines going into the intake elbow and find oil in them, I guess that would be the answer I'm looking for, right?
Please pitch in anybody?
Giovanni

gio64

iTrader: (1)

...Any takers???

dgeesaman

iTrader: (7)

I think you'll see some oil in them always unless your turbos have very tight seals and your intake is absolutely dry of oil.

If I were you I'd simply take a Mityvac and check these valves by disconnecting at the primary turbo inlet connection.

Dave