Oil bypassing turbo seals

[whrdnsx]

I have the HP turbo kit with GT35R Ball Bearing turbo.
I have 2 restrictors fitted to the oil feed line. I have oil bypassing the seals in the turbo which ends up in the intercooler & inlet manifold. Originally with only one restrictor the oil would leak into the exhaust side of the turbo also. The turbo rebuilder claimed Ball bearing turbos do not like too much oil pressure, drain restrictons & crankcase pressure.
The turbo has been rebuilt & balanced & has less than 500 miles on it.
The turbo shop claims my breathers on the engine are not large enough (2 x dash 6 lines to catch tank)& therfore pressurising the engine causing the oil to leak pass the seals.
The Turbo shop recommends going to 2 x dash 12 lines. Which I thought was excessive since I'm only running 7psi. The engine is otherwise unmodified & in good health.
Just wondering if anyone else has had this problem.

 

[Elite]

I'm not sure what your crankcase pressure has to do with your turbo leaking oil? If you were having ring/blowby issues or something then sure. But your turbo issues are probably/possibly due to your oil return line. If you have the proper restrictors in the feed line, then you have to look at your entire return system.

BTW, -10 and -12 crankcase vents are all the rage in the Honda world these days. They work, but this probably isn't your turbo issue.

 

[angus]

If you were "over oiling" the turbo , then you may have damaged the "piston ring" seals in the turbo , also what size orifice are you using? it should be in the range of .030 , once the piston ring type seals in the turbo are distorted they will never seal .
If your crankcase pressure is too high , it is the same as restricting the drain, I have built so many turbo hondas over the years and I can tell you that every car seems different , you can put the exact same setup on ten cars and one will blow oil past the oil seals , you could also look at the oil tank from sos which allows the turbo oil to drain while being unaffected by crankcase pressure , maybe your car has broken ringlands causing more pressure?
This is why I actually prefer the oil pump for the return line.

you also mention two -6 breather lines, how / where are they plumbed? are you still using the stock PCV valve? is it funtioning 100% ? if it leaks even slightly under boost (the opposite way to how they are usually tested) then it will pressurize the crankcase.

 

[whrdnsx]

My breathers are from each cam cover into a Dali Coolant/catch tank. PCV has been removed.

Return line is dash 10 & although only a gradual decline to the sump, it seems to be draining fine. (no buildup of oil in the line) this may have been the issue originally as I changed the position into the sump to get a better run to the sump.

I hoped to avoid having to use a scavenge pump for the return, that was why I chose the HP kit.

 

[angus]

My breathers are from each cam cover into a Dali Coolant/catch tank. PCV has been removed.

Return line is dash 10 & although only a gradual decline to the sump, it seems to be draining fine. (no buildup of oil in the line) this may have been the issue originally as I changed the position into the sump to get a better run to the sump.

I hoped to avoid having to use a scavenge pump for the return, that was why I chose the HP kit.

Your problem is caused by the removal of the PCV valve , this is BAD.
Without a PCV valve your crankcase pressure is too high , causing the backpressure in the drain line , add the pcv back and within a few miles ,the oil should go away , unless you have damaged the oil seals again.

The PCV valve acts as a "vacuum" in your engine , sucking out the pressure in the crankcase under deceleration, with your current setup , the engine builds pressure and it cannot escape , causing your turbo to see pressure in the drain line.

 

[whrdnsx]

Your problem is caused by the removal of the PCV valve , this is BAD.
Without a PCV valve your crankcase pressure is too high , causing the backpressure in the drain line , add the pcv back and within a few miles ,the oil should go away , unless you have damaged the oil seals again.

The PCV valve acts as a "vacuum" in your engine , sucking out the pressure in the crankcase under deceleration, with your current setup , the engine builds pressure and it cannot escape , causing your turbo to see pressure in the drain line.

My catch tank is vented to the Atmosphere so there is no chance of building pressure in the crankcase.

I've also recently increased the size of the vent hole in the catch tank(now 9/16"), so i will check again to see if this may have contributed. as the hole was quite small (5/16")

 

[jdm monkey]

Hows the oil return line? Is there a kink or block on the line?

 

[whrdnsx]

This was my first concern as it was quite difficult to get a good run/decline back to the sump. I changed this 3 times before I was happy there would be no problems. Although there is only a gradual decline to the sump. upon inspection there has been no oil build up in the drain line. So I'm satisfied that the oil drain is not causing the problem.

 

[angus]

My catch tank is vented to the Atmosphere so there is no chance of building pressure in the crankcase.

I've also recently increased the size of the vent hole in the catch tank(now 9/16"), so i will check again to see if this may have contributed. as the hole was quite small (5/16")

What you seem to be missing , is that although your catch can is vented to the atmosphere , your PCV ( POSITIVE CRANKCASE VENTILATION) valve is missing, hence the pressure in your crankcase, and the leaking turbo.

The original factory setup allows the one valve cover to be evacuated by the venturi affect of the intake tube being tapped so that under acceleration it creates a vacuum in the crankcase. In addition to this the PCV valve creates vacuum on decel.

The larger lines to your catch can will do nothing to create a vacuum in your crankcase , which is what you need and what honda intended when they designed the PCV system .
I have dealt with this problem pretty extensively in honda engines , and venting the motor to the atmosphere doesn't usually work very well , you can add a catch can , but the original PCV valve should be used in the original hole in the valve cover.

 

[Devin@AEM]

whrdnsx - it is highly unlikely that removing your PCV will have anything to do with the turbo oiling issue. I've run this way for years and haven't had any oiling issues or excessive crankcase pressure. Adding a PCV back into my system would likely increase crankcase pressure at high loads (would prevent the front valve cover from breathing under boost).

My current setup uses 2 x -8AN lines (one from each valve cover) to a catch can and breather.

 

[Cody@LoveFab]

We are approaching 40 NSX kits and have run the engines vented to the atmosphere (using breathers and/or catch cans) as well as utilizing the factory PCV valve setup. We have yet to notice any smoking problems with the turbo and haven’t enlarged the factory valve cover vent sizes. These results are from both gravity and oil pump drained turbo setups.

I would contact HP to find out what they suggest as it is their system after all. IIRC, Scorp965 had turbo issues out of the box - perhaps you received a bad turbo as well.

Do you have any pictures of your oil drain? Perhaps you are overlooking something that is easily resolved by posting a few pictures.

 

[whrdnsx]

We are approaching 40 NSX kits and have run the engines vented to the atmosphere (using breathers and/or catch cans) as well as utilizing the factory PCV valve setup. We have yet to notice any smoking problems with the turbo and haven’t enlarged the factory valve cover vent sizes. These results are from both gravity and oil pump drained turbo setups.

I would contact HP to find out what they suggest as it is their system after all. IIRC, Scorp965 had turbo issues out of the box - perhaps you received a bad turbo as well.

Do you have any pictures of your oil drain? Perhaps you are overlooking something that is easily resolved by posting a few pictures.

Yes, That's what I thought. I only purchased the Hotside parts from HP. It was trouble enough just with those parts.
I think I have a dodgy front seal in my turbo. I think I have addressed everything that could possibly cause this problem.

My Turbo has a Garrett bearing Housing but has been modified somehow to Run Ceramic bearings by "Mr Turbo" in Australia.

My problem seemed to be reduced when I added an extra oil feed restrictor. I have one on the Turbo (about 30thou) & another on the oil filter housing. Is there somewhere on the engine that would have less oil pressure? (cyl head perhaps) "Mr Turbo" claimed that he experienced a similar problem on another engine with high Oil Pressure (1000HP supra engine) it was cured by running 3 restrictors & -3 line. I have yet to try this but seems extreme considering my mild setup.

I will post some pictures of my setup when I return from Holidays for comments.

Thanks

 

[Keen]

I also have been battling oil leakage into the intake/exhaust through the turbo. I believe my issues are different than whrdnsx's.

My original return system composed of a tilton / mocal pump from summit and reservoir. This worked for about 1.5 years; however, here are the issues I was having with it:

• the pump is big and heavy
• the pump was rattling itself to pieces
• it is loud
• it requires a reservoir
• this pump is a diaphragm pump and may not be meant to handle hot oil

So I changed to the standard pump (2.6 gpm) from here:

http://www.rbracing-rsr.com/oilsystems.htm

This site gives a lot of info about different oil pumps and shows a simple way of testing a return pump by having the turbo drain into a bucket while the pump removes the oil from the bucket. I tried this out up to 5000rpm and it works great (it sucks the bucket empty with constant engine rpm).
The things I like about it are:

• it is a gear pump that is made to handle hot oil
• it is compact
• it is quiet
• it does not require a reservoir

However, I get oil in my intake if I park with the nose of the car pointed up a hill. It appears the oil is making its way backward from the oil pan, through the return lines and pump and some how getting past the turbo seals. Or, the oil is continuing to flow into the turbo after the engine is turned off. Or, something is going on that I'm not thinking about. Any ideas?

My -8 oil return line enters the back side of the oil pan at 1.2" from the top of the pan (the lowest point in the fittings opening, not center line). I am using a GT35R that has not been modified, 0.030" restrictor with -4 feed lines, and an inline oil filter for the turbo. The oil feed is sourced from the oil filter bracket where the oil pressure switch is.