Help...White Smoke, no boost, rear turbo grinding noise

[ArmyJeff]

OK So I finally got around to the turbos and the rear turbo was completely shot with a lot of shaft play. the smoke must have been from all the oil spewing into the exhaust. So I ordered 15Gs from IPS and just got done installing the rear one. Car runs great and holds boost perfectly. Still got a little smoke, not sure, but I will see if it clears up after I replace the front turbo.

[ArmyJeff]

No more smoke, but oil pressure looks low to me. it fluctuates with boost, but still seems low. Any advice?

[Hannibalzero]

Originally Posted by ArmyJeff

No more smoke, but oil pressure looks low to me. it fluctuates with boost, but still seems low. Any advice?

Are you using the stock guage or an aftermarket guage to determine oil pressure?

The block has large ventilation passage that allows any piston ring blowthough gasses to escape the crankcase. Boost should not affect your oil pressure noticeably. Are you sure the pressure fluctuations aren't RPM related?

[ArmyJeff]

Yes they are RPM related. Sorry I was confusing in my last post. Car boosts great and oil flows through both turbos (as seen from feed and new return lines) At idle the oil pressure sits at about 2-3 tick maks about the bottom. When RPM raises up from 3000 and above the oil pressure increases for a period of time. During normal highway driving it fluctuates around the first large tick from the bottom. I guess it seems as if it is reading low at idle. No oil pressure warning light so far. I am doing an oil change and replacing my PCV valve tomorrow. ANy other advice? Thanks

[Hannibalzero]

Originally Posted by ArmyJeff

Yes they are RPM related. Sorry I was confusing in my last post. Car boosts great and oil flows through both turbos (as seen from feed and new return lines) At idle the oil pressure sits at about 2-3 tick maks about the bottom. When RPM raises up from 3000 and above the oil pressure increases for a period of time. During normal highway driving it fluctuates around the first large tick from the bottom. I guess it seems as if it is reading low at idle. No oil pressure warning light so far. I am doing an oil change and replacing my PCV valve tomorrow. ANy other advice? Thanks

The oil pump is crank driven. When the crank spins faster, the oil pump gear spins faster, and thus pressure increases. It is perfectly normal for your oil pressure to fluctuate based on RPMs. If it didn't, there would be a problem.

Don't expect the stock oil pressure guage to give you an even remotely accurate reading. It is about as effective as that stock "boost" guage. (As in not accurate at all.) You're best bet is to get an aftermarket oil guage and see where your oil pressure really is.

What weight oil do you plan to use? If you are concerned about pressure, you may want to try a 10w40 or 20w50 synthetic. Also, the type of oil filter can affect pressire as well.

[ArmyJeff]

Im using 10W30 right now with a Fram (High Mileage additive) filter. I just put in a new PCV and no change either. I will do an oil change most likely this weekend. Otherwise, I am changing the front Turbo as well and the foil feed and return lines. I will let you kow what happens. Any advice? What should my guage read at idle/sitting in nuetral at a stop?

[Hannibalzero]

I have heard some bad things about Fram filters. I'd try using something else. I am pretty happy with Puralator Pure filters. Go for some 10w40 synthetic while you're at it.

I really couldn't tell you where the pressure guage should fall at a warm idle. It is so inaccurate that it really isn't helpful at measuring oil pressure anyway. Off the top of my head, I want to say that the service manual states that 11psi is the minimum oil pressure you should have. I believe normal oil pressure should fall between 15-17 psi. There really isn't any type of corralation between the stock guage and an actual pressure reading though. Hope that helps.

[ArmyJeff]

What would I need to check oil pressure? Where and how do I connect a different gauge? Thanks

[Hannibalzero]

Originally Posted by ArmyJeff

What would I need to check oil pressure? Where and how do I connect a different gauge? Thanks

There's a couple of methods. You could unscrew the stock sender and replace that with an aftermarket sending unit. The alternative is to buy an oil filter sandwhich plate - remove the oil filter, screw the plate into the oil filter housing, then screw the oil filter (new) onto the sandwhich plate threads. Once you have a pressure sender in place (in either location) run the wires into the cabin and mount the guage.

[Hannibalzero]

This pic will show you where the stock pressure sender is located...


And this is what the sandwhich plate would look like...


Installation instructions are here...
1995 3000GT: Defi Oil Pressure And Temperature Sensors Installation