turbocvette

My diy turbo is near the end!
I have a front mount turbo sitting low in front of the radiator with 10an drain about 8" long into a scavenge pump then down to 8an back into the valve cover. I am getting oil out of the exhaust side of the turbo. My question is I believe I need a check valve possibly 2?
Should i try 1 just after the scavenge? Or 1 before the scavenge?
I think what is happening when i shut the car off its all draining back down the return line up back into the turbo. I cant really get a good diagnosis on the best fix. Anyone have a proven setup with a check valve?

slow ride

If you are draining high to the valve cover then it probably is returning back. Your feed can bleed down at shutdown also. I'd run a small check at the turbo oil feed inlet and a large one in the oil return line.

What pump is it and is it at the turbo drain level or higher? I use a single check to feed both turbos from the oil sender location and one on the exa pump outlet, but mine does run to the pan so not quite so high. My oil pump is just a few inches higher than the turbo drains, but the turbos are tilted. I also run a 20-30 second timer relay on shutdown to clear the lines better.

turbocvette

I am a bit confused right now. I did a test and turned the pump on with the car off and it pumped out a quart of oil and did not stop! I have my feed line above the oil filter and the return on the same side valve cover. The pump if i remember correctly came from rb racing and it worked just fine the last time i used it on a turbo busa. I will give the check valves a try and see what happens. Its almost like i was pumping all the oil out of the motor? Pump is mounted below the turbo about 8"

slow ride

Well if the oil passages were primed in the engine the scavenging pump might be able to pull oil from the engine passages. I suppose it might even from the pan through the engine oil pump and pickup. It doesn't seem that weird to me. Just picture siphoning water out of something.

turbocvette

I am going to go ahead and do that run both and hope it solves the problem. Might have a blown seal as well but check valves needed anyway. Also just installed what seems to be a bad converter ptc brand new shaking like crazy! Kinda sucks was hoping to tune soon but looks like the trans has got to come back out.

stevieturbo

I'm sure it would take a lot of effort for the scavenge pump to draw oil from the pan through the oil galleries and pump etc. A LOT of effort

But if the pump is low and oil discharge into the engine high, a check valve mounted close to the pump on the discharge side would probably make sense.
or if it has a really light internal spring, it could go on the entry side to the pump.

Also, with a low mounted turbo, oil can syphon and drain into the turbo after shutdown which can saturate it. A check valve on the feed into turbo can sometimes help if that's the case. But that's a separate issue from the first although similar end result.

albrntout

Check valves, small ones 1-2psi; go back to 10 an unrestricted the whole way. Also make sure turbos are spinning engine idle during testing yes oil burning will happen, sump pumps won't suck much volume why You have 8an on push side , turbos still don't drain sitting still. In my case had a kn filter inline in my an-10 return using exapump too suck from outlet of turbos. Caused pressure to drop too much for exapump to overcome efficiently, filled filter with oil too slow pushing oil to valve cover. It built psi on return side of turbos which forced oil out exhaust side, and insult it would drain back into turbos as well. Ditched all restrictions on push side of pump was only solution for me. Guessing ditch 8an it'll solve it.

stevieturbo

I have no clue what you're trying to say there ?

albrntout

Sorry, I phone editing is a pita point being. If you don't have check valves you need one minimally, on feed to turbos, sometimes two one in and one out and they should be low psi check valves 1-2 psi, it's hard for a sucking pump to overcome restrictions, they have to prime. Any restrictions even a k&n an10 inline filter causes a problem (my own experience ). What you describe in your return has a similar problem as you are going to a larger volume hose (pooling area) then to the pump (which has a hard time priming, due to the Air in the line in that larger diamter hose run.) Pump loses battle can't extract air and prime (not acting as a pump now, instead acts as a barrier) oil pressure builds up, forces oil by seals. And or secondly you have it going to 8 an on pressure side of pump... you did that to increase pressure, but it decreases overall flow and slows pumps ability to scavange from suck side. So it's spraying oil harder into valve cover which doesn't help (think water hose, pinch it and it sprays water at faster rate). Then testing your system and saw it work.. With no check valves and sitting allowed oil in to fill cavity of larger hose (air bleeds back to highest point through pump) hence your test shows pump working it can now prime as pool was full of oil not air, pump works as a pump not barrier.. Second this is a possible issue, if you have a high volume high pressure oil pump feeding turbos. Turbos don't like tons of psi, in fact most want 15-25 psi, you may need a pressure bleed bypass type solution and your return is fine. Some ideas from experience of dry sumping rear mounts, and it feeding from turbo. Either your pump can't prime, the 8-an won't let it flow enough to keep up with turbo with pump working, or too much oil pressure at turbos to begin with. My monies on priming of pump and 8-an restriction