Turbo oil feed related problem!

[PshlosE30]

Hello guys I have an M50B20 nv engine and some days ago i completed my turbo project (Garrett T25, stainless steel/double OEM HG, Turbosmart 38mm external wastegate, Ecumaster DET3 piggyback, secondary fuel rail).
I used an ebay cast manifold (terrible choice for E30 M50 swapped) and turbo "sits" too low and much away from the oil pan. So return line was almost a 30cm pipe, parallel to ground. It was burning oil like MF during idle and on boost.
Found out that some subaru guys,use power steering pumps for low mount applications, which i did too. Used my old power steering pump from my E34 with success.No more burning oil during idle,boost or normal driving,unless you turn off the engine. Whenever turn off the engine and pump stops scavenging oil in pan, the oil that there is in feed line, travels down with the gravity fills the turbo cartridge and leaks in exhaust side.
When i start up the car,let it warm and boost it,it will smoke like MF again (it burns the oil that leaked on shut down phase) for 4-5 secs,then no smoke again until shut down.

Is there any valve that closes when no pressure in the oil feed to prevent drip? Found out that these types of valves called "rupture valves" and they use them in elevators or agricultural machines, but they work with hydraulic oil and no more than 80 celsius of temperature.

Also i fabricate a drip tank between turbo drain and pump,but it didn't help,because pump it above oil level in turbo drain,so the tank is all the time flooded with oil..


Thanks in advance!

[JehTehsus]

Could you use an oil pressure relief valve?

[PshlosE30]

Could you use an oil pressure relief valve?

Thanks for your reply mate! I searched for oil pressure relief valve with no luck,but found on an online store for Porsche parts,that they offer a ball type check valve to eliminate oil residuals in feed system,and to eliminate blue smoke on startup. It's kinda pricey (52 usd) for such a simple valve,I'll try to locate something similar locally. Would you think that a ball type check valve would do the job?

[JehTehsus]

Thanks for your reply mate! I searched for oil pressure relief valve with no luck,but found on an online store for Porsche parts,that they offer a ball type check valve to eliminate oil residuals in feed system,and to eliminate blue smoke on startup. It's kinda pricey (52 usd) for such a simple valve,I'll try to locate something similar locally. Would you think that a ball type check valve would do the job?

Just to make certain, you want a valve pre-turbo that closes when there is basically no oil pressure, so that when the motor is off you are not leaking any additional oil into the turbo/pump etc?

I don't know of any part numbers/specific valves off hand, but a quick google search shows you can get various inline oil pressure relief valves. Exactly what pressure they are set for depends; you want one with a very low pressure ideally (maybe like 10 PSI) so it is basically always open when the engine is running (you want fresh oil in that turbo cooling it ASAP) and making oil pressure but closes once it is off. What you may be able to do is find an existing valve and simply cut the internal spring and reassemble it such that it takes very little pressure to open, but ideally you can just find a pressure relief valve designed for lower pressure operation.

All that said I don't know if this will prevent the issue you are seeing, as there will still be some oil in the turbo when the valve closes. Maybe an electrical scavenge pump that you can run for a few moments after shutoff would be ideal (and no valve at all) that basically sucks all the oil out of the feed and dumps it into the pan?

[PshlosE30]

Exactly,i want a valve pre-turbo! Very clever that about spring cut, definitely I'll give it a try.. As for electric scavenge pump,it would be easier to mount and make circuit with relays etc but whatever pump i searched for,had a duty cycle.. I use this car as daily, sometimes for long trips too, and with Greece's hot weather during summer, i cant risk to idle in heavy traffic without oil scavenging. Belt driven pumps are more safe IMO.. Nvm, i ll try a pressure relief valve,hope it will do the trick! Thanks for your time mate!

[Northern]

Could you lower the pump so it doesn't flow back from the pump? does PS pump have any sort of check valve in it?

[PshlosE30]

Could you lower the pump so it doesn't flow back from the pump? does PS pump have any sort of check valve in it?

Hey mate,ps pump is for oil scavenging to oil pan,and yes,it has a check valve,it can't return the scavenged oil from pan,back to the pump. The problem is at the oil feed,i use a "T" on the stock oil pressure sensor, near the oil filter.. Because feed line it's higher than turbo cartridge, it's floods the turbo when ps pump it's not working. As JehTehsus said,an oil pressure relief valve with custom spring maybe do the job. Currently i work 7/7 and 12 hours a day and haven't time to test it,I've left the car in garage and use my father's VW t3 as daily :P hahaha I'll write a feedback when try that solution...