Results 1 to 5 of 5

Thread: Oil catch can 3.9 V8

  1. 25th November 2009, 03:25 PM #1
    Utemad's Avatar
    Utemad
    Utemad is offline TopicToaster
    Join Date
    Jan 1970
    Location
    Dalby
    Posts
    4,011
    Total Downloaded
    0

    Oil catch can 3.9 V8

    Hi folks,

    I was thinking of fitting an oil catch can to my 3.9 V8 to keep the oily gunk out of the intake.

    I looked it up in the RAVE manual to see how it works as I know there is a splitter and the main hose enters the air intake just after the AFM and the smaller one goes into the plenum.

    From RAVE it looks like the oil vapour is not just blown out of the rocker cover but is also sucked from the vacuum of the intake. It looks like the oil is meant to only go into the plenum and not into the larger post AFM hose as it is only meant as a vacuum hose to help it all along.

    So what would happen if I did fit a catch can and blanked the other two hoses off?
    Would the fact the oil vapour has not got the vacuum assistance be a problem?

    Also how does the three way connector work? It must be more than just a plastic splitter if the oil vapour is only meant to go out one way. Doesn't seem to work too well though as I pulled the hoses off mine and there is oil residue in the hose to the AFM.

    Any tips?
    Reply With Quote Reply With Quote
  2. 25th November 2009, 04:11 PM #2
    PhilipA
    PhilipA is offline Swaggie Subscriber
    Join Date
    Jan 1970
    Location
    Avoca Beach
    Posts
    14,152
    Total Downloaded
    0
    The oil hose does not go anywhere near the MAF, it goes into the inlet manifold at the throttle butterfly.
    In normal circumstances the system works well as there is an oil shield inside the rocker cover, and any vapour should be caught in the separator that screws into the rocker cover. The T piece going to the plenum has a tiny hole to the ventilation so not much oil should go that way. A clean every 10KK or so is all that is needed.

    However once the engine is very old and has lots of blow by then it can be overpowered, but this is more a comment on the condition of the engine than anything else.

    If you have gas then sometimes the fitters move the sump ventilation outside the gas ring AFAIK to avoid gas explosions in the sump. If they moved it upstream of the MAF this is obviously bad practice as it will soon foul the MAF. Maybe if you installed another vapour trap it would help , but probably enough still would get through to cause problems.

    Regard sPhilip A
    Reply With Quote Reply With Quote
  3. 25th November 2009, 04:52 PM #3
    Utemad's Avatar
    Utemad
    Utemad is offline TopicToaster
    Join Date
    Jan 1970
    Location
    Dalby
    Posts
    4,011
    Total Downloaded
    0
    I have cleaned the steel wool separator thing twice before.
    Maybe I should clean all the hoses and bits and pieces and then see where the oil gets to before I divert it altogether.

    The engine has 220k on it so it won't be as good as new and there will be some degree of blow by. It runs fine however.

    On the 3.9 the hose is attached to the AFM. There is a fitting for it on the AFM housing itself but on the engine side of the housing so no oil contaminates the wire.
    However as said this hose only appears to be for the vacuum and the oil should be going into the plenum.

    I'll give the whole lot a clean and see how long it takes for oil to get to the end of the hoses again.
    Reply With Quote Reply With Quote
  4. 25th November 2009, 08:21 PM #4
    PhilipA
    PhilipA is offline Swaggie Subscriber
    Join Date
    Jan 1970
    Location
    Avoca Beach
    Posts
    14,152
    Total Downloaded
    0
    They must have changed it after my 92 3.9. Also the Thor manifold from 1999 on feeds it in near the throttle blade, so I assumed they would all be the same.

    Learn something every day.
    Regard sPhilip A
    Reply With Quote Reply With Quote
  5. 26th November 2009, 03:47 PM #5
    Utemad's Avatar
    Utemad
    Utemad is offline TopicToaster
    Join Date
    Jan 1970
    Location
    Dalby
    Posts
    4,011
    Total Downloaded
    0
    Quote Originally Posted by PhilipA View Post
    If you have gas then sometimes the fitters move the sump ventilation outside the gas ring AFAIK to avoid gas explosions in the sump. If they moved it upstream of the MAF this is obviously bad practice as it will soon foul the MAF. Maybe if you installed another vapour trap it would help , but probably enough still would get through to cause problems.

    Regard sPhilip A
    Guess what?

    You're right!

    I just finished pulling all the pipes off and cleaning them and when I looked closer at the MAF connection I realised that it is not actually a factory fitment but it has been drilled and tapped.
    I saw the original point that the larger crankcase ventilation pipe goes to right before the butterfly.

    So as you said the LPG fitter has moved the pipe to before the LPG ring so as not to fill the sump with LPG.

    There seemed to be a fair bit of oil residue in the intake pipe and the plenum though. So I've blocked it all off and cleaned it up as best I can without pulling off the plenum etc. This way I can see how much oil is coming out.

    I probably have the issue of the head gaskets leaking pressure into the valley of the motor. I've read it is common and the heads have never been off AFAIK.

    Thanks for the info.
    Reply With Quote Reply With Quote
« TD5 rattle/power loss | Defender TD5 R380 Gearbox Oil Cooler pipe (loop) »

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Forum Rules

Search AULRO.com ONLY!
 Search All the Web!