Maybe on cold startup, that's it. Do you think he can get away with an oil that's 0/10W-20? Are you sure there's not something preventing the oil from draining back into the block fast enough?
Turbo restrictors and filters...
- Thread starter Supra
- Start date
Chris - Remember when I helped you with your IC system and how exceeding critical velocity would cause a pressure rise, restricting flow? Guess what?...air is a fluid just like oil 
He is exceeding the "critical velocity" of his oil system, and his turbo drain line based on the seal's ability to stop oil from pushing past it.
The big difference is density...air will compress, oil will not for all practical purpose. Changing grades of oil will help, but not enough in this case. That does assume there is nothing in the drain line slowing flow down.
He is exceeding the "critical velocity" of his oil system, and his turbo drain line based on the seal's ability to stop oil from pushing past it.
The big difference is density...air will compress, oil will not for all practical purpose. Changing grades of oil will help, but not enough in this case. That does assume there is nothing in the drain line slowing flow down.
I'm not a big fan of shimming the 7M oil pump that much...the motor was designed with a high volume, low pressure system. I know guys do it, but it can cause problems like this one and it's hard on the pump. Now that it's done, taking the shims out would be a royal PITA, but would be the best solution.
Personally, I think there are several things that can be done to help this problem without removing the pump.
1) Go to a full flow, thermostat controlled cooler circuit. The longer piping and a remote filter will reduce some of the pressure before it hits the motor.
2) Could install a bypass filter pre oil cooler on this circuit that will bleed off a small amount of oil, filter it, and dump back into the pan before it ever gets to the block. A full flow cooler/remote filter circuit will not use the stock cooler return on the pan...perfect for this. This will reduce some pressure too.
3) Don't use more than a 10W-30 weight oil...I would use a "true syn"
4) Use a -3 turbo oil feed line...if necessary, use a restrictor.
Personally, I think there are several things that can be done to help this problem without removing the pump.
1) Go to a full flow, thermostat controlled cooler circuit. The longer piping and a remote filter will reduce some of the pressure before it hits the motor.
2) Could install a bypass filter pre oil cooler on this circuit that will bleed off a small amount of oil, filter it, and dump back into the pan before it ever gets to the block. A full flow cooler/remote filter circuit will not use the stock cooler return on the pan...perfect for this. This will reduce some pressure too.
3) Don't use more than a 10W-30 weight oil...I would use a "true syn"
4) Use a -3 turbo oil feed line...if necessary, use a restrictor.
All of those involve putting some money into the car, some a lot more then others. Taking out the shims if fee! But like you said, a royal PITA. He may want to refer to the "redneck bearing fix" thread to get a good idea of how big of a PITA it is .
.jdub said:
After much discussion on the internet and phone I clearly have two problems. The oil pressure seems too high, and the turbo smokes. The first may be contributing to or causing the latter.
Since I discovered the oil pressure problem yesterday, I need to spend some time making sure the stock cooler system is working. If the stock cooler is not bleeding >40psi then fixing this may reduce oil pressure/volume enough to stop the smoking. Plus I have a tight tolerance motor + oil only cooled turbo. That's a recipe for lots of heat and not where to cool it. I will add an aftermarket cooler as soon as possible.
Consensus is that a restrictor/filter on an oil only cooled turbo isn't a great idea (you're restricting the only fluid cooling the turbo) so I'm going to focus on doing whatever it takes to get the turbo to drain and be happy. After talking to a few others, I will try to rotate the center section to have more of an angle to help promote better draining and triple check the drain line for debris and poor angle. I'm going to switch oil brands to Pennzoil and see if that makes any difference. I'm not going to switch oil weights.
If that doesn't work, I'll have to think up something else, or ship the turbo off and have it inspected.
Will know more later this week, after the snow hits and melts. Road salt FTMFL. :3d_frown:
starscream5000 said:All of those involve putting some money into the car, some a lot more then others. Taking out the shims if fee! But like you said, a royal PITA. He may want to refer to the "redneck bearing fix" thread to get a good idea of how big of a PITA it is
My budget is more generous than most and I have a fully equipped garage + do my own labor. Also keep in mind I have a bad tranny as well which will be swapped for a built R154 once I know the motor is solid. So if de-shimming the pump is what needs to be done, it's not much harder to pull the motor & tranny than to swap the tranny alone. Tomorrow I'll have a set of Eagle rods & ARP hardware itching to go in. Those are for the "spare motor" but if i do yank this one out early, I'll certainly be jack stand racing for a few months.
What's really frustrating me about the whole ordeal is that EVERY problem I used to have is gone. Now I have a slew of new little problems...
Per the previous post:
The relief valve on the filter housing could very well be a contributor...sounds like you've got a handle on the problem Rich.
Is the cooler warm after you run it?
BTW - I'm using a -3 line on my SP turbo...provides plenty of oil to the turbo (oil cooled only).
jdub said:
The relief valve on the filter housing could very well be a contributor...sounds like you've got a handle on the problem Rich.
Is the cooler warm after you run it?
BTW - I'm using a -3 line on my SP turbo...provides plenty of oil to the turbo (oil cooled only).
I was going to say ,a smaller line feeding the turbo will would be a little better than a restricter.