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Thread: Are my turbo seals blown?

  1. Default Are my turbo seals blown?

    So we have been getting this question a lot from guys with both stock turbo and upgraded turbo.

    There is oil in my intercooler pipe. Are my turbo seals blown?
    So for you guys that are unfamiliar with turbo seals and how they work, here is a little info.

    First of all, turbo seals may let some oil out, but that doesn't mean they are blown. There are a lot of different pressures that are involved as well as other places for oil to come from. Turbo seals are usually a piston ring style seal and they are designed to keep pressure out of the oil passages and therefore the crank case but they are not exactly designed to keep oil from getting out of the the oil passages when there is no pressure on the compressor or turbine side of the seal.

    When oil goes into the bearing housing, it is under pressure and mixes with air due to turbulence as it passes between the bearing and journal surfaces. Oil is brought in under pressure but it leaves via gravity. That is why the oil drain is so much bigger than the oil feed. As it drains out, it is frothy and light and anything that impedes this gravity flow will cause the frothy oil/air mixture to stay in the bearing housing. Once it rises above the level of the turbo seals it has the ability to leak into the compressor and turbine housings.

    However, there are other issues that can cause this besides a malfunctioning drain.

    Most people, when upgrading turbos, will already have a catch can but some people keep the valve cover vented into the intake. In a lot of cases that we have seen, the oil in the hot charge pipe and in the compressor come from this. As blow by gas and vapor escape the valve cover, they have no where to go but back through the turbo. A good idea if you do not already have a vented catch can is to grab one of these from the local hardware store.



    This breather filter will save you from venting gross blow by gasses back into your intake and turbo system. Don't forget to block off the port on the intake where the tube connects from the valve cover though because then you end up with a massive influx of un-metered air which could cause you to run lean.

    Walking back from there, another cause for oil to be present in your compressor housing can also be as simple as a dirty air filter. As the intake filter becomes increasingly restricted, it will cause a pressure drop. This will cause a partial vacuum at the compressor inlet during idle or low load situations. This can cause oil to be sucked from the bearing housing through the seal an into the compressor outlet. The same problem exist when your intake or filter are too small. This doesn't occur at WOT when there is ample pressure in the compressor, but only when a vacuum can be created by lack of flow to the turbo. Also, you will only see oil in the compressor outlet area if this is the root of your issue. The solution to this is simple. Just clean your air filter regularly. Also, it is a good idea to have a properly sized intake, though this is not a common problem as most people pick up a 3" or 3.5" intake before upgrading the turbo.

    If you are seeing oil on your turbine outlet, the cause for this is most likely an inability for the oil to drain properly from your turbo. You will need to make sure that the drain port on your turbo is pointed straight down. Also, make sure that there is no "grease trap" sag in your oil drain line and that it is as straight a shot as possible from the turbo to the port on the block. Another issue is that sometimes on steel braided lines, the line can become pinched on the the inside while the outside cover remains normal. Check and make sure there are no internal blockages.

    I hope this helps clear some of the blown turbo seal questions up for you guys experiencing the problem! Let me know if you have any questions or if you have anything to add, please post it up!

  2. #2
    Join Date
    Oct 2012
    Location
    Brisbane Southside
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    527

    Default

    Thanks guys, this is very informative. I do however have oil leaking from my BNR S3 on the join between the turbine housing and the CHRA. It can also be witnessed in the blue-ish smoke at the tail pipes on shifts.

    I have fitted 2, yes 2 OCC's, one with a new check valve/non return valve (to assist the PCV) and the other between the TIP and the valve cover with NO check valve........which does not seem to make any change.

    I am about to get the turbo off to inspect to see if it is indeed the cause. Are there any other checks/tests I can do?
    Cheers

    Grumpy

    Tuned with
    By Alex...........

  3. Default

    Quote Originally Posted by Grumpy View Post
    Thanks guys, this is very informative. I do however have oil leaking from my BNR S3 on the join between the turbine housing and the CHRA. It can also be witnessed in the blue-ish smoke at the tail pipes on shifts.

    I have fitted 2, yes 2 OCC's, one with a new check valve/non return valve (to assist the PCV) and the other between the TIP and the valve cover with NO check valve........which does not seem to make any change.

    I am about to get the turbo off to inspect to see if it is indeed the cause. Are there any other checks/tests I can do?
    It does sound like you are leaking oil past the seals. You shouldn't see oil on the CHRA though. That means either the oil return or feed line is leaking. It is most likely the return line because the feed line is under much more pressure and would make a much bigger mess if it was leaking. And if the oil return line is stopped up, that could explain the oil getting past your seals.

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