DS Crankcase Breather
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  1. #1
    Fellow Frogger! marc61's Avatar
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    Default DS Crankcase Breather

    I'd like to check that the green hemispherical crankcase breather that's bolted to the side of the engine isn't clogged up as I can't feel or smell anything coming out of it. I remember its held on by one very long bolt, but is there enough room to get this off with the engine in place?

    I'm thinking loosen the engine mounting bolts and jack the engine vertically to get some clearance, but from staring at it I'm not convinced there's going to be enough horizontal space to get the bolt out. Has anyone done this in situ, would appreciate knowing if it's possible before I give it a go.

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    Cheers, Marc.

    1987 CX GTi T2 Maikonics
    1972 SM 2.7 carb
    1972 DS21 EFI

  2. #2
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    I've just checked the parts book which seem to suggest its 75mm long. Does that help?

  3. #3
    Fellow Frogger! marc61's Avatar
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    Thanks, that's even longer than I remembered. Starting to seriously doubt if it's removable with the engine in the car.
    Cheers, Marc.

    1987 CX GTi T2 Maikonics
    1972 SM 2.7 carb
    1972 DS21 EFI

  4. #4
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    It's morning here in the UK. I've just checked a spare i have in my workshop and it is indeed 75mm long. My engine is out of the car so can't comment on whether it could be removed in situ. i just have to reach up to a shelf to get mine......What i can say though, is that i found it was full of lots of sticky, gunky burnt grease when i first removed it from the car.

  5. #5
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    Try compressed air in the oil filler and see if there is any airflow from the two breathers. The one on the rocker cover is easily removed and cleaned in solvent. Carby cleaner will normally remove what a petrol wash leaves behind. I think the one on the block has a punched metal plate inside it? You may be able to slacken the bolt and wash it out with solvent if access is no good.

  6. #6
    1000+ Posts garyk's Avatar
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    I am (very) reliably told that the breather can be removed with the engine in the car....
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  7. #7
    1000+ Posts forumnoreason's Avatar
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    best way to find out clear some space to reach and off you go! Probably just hand turn bolt out after loose to get it rest of way out, can't remember if they have a seal. Yes they do rubber joint, might be worth either replacing or use some hylomar to cheer up on reinstall.

  8. #8
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    Guys. What would the symptoms of a blocked breather be. All this has got me thinking it needs to be checked

  9. #9
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    If the crankcase can't breath and there is piston ring blowby, you may see oil leakage from the rear main seal. This is likely to be more of an issue on older engines with an asbestos rope seal and scroll, the rope seal not actually being tight on the crankshaft like a later rubber lip seal.

  10. #10
    Fellow Frogger! marc61's Avatar
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    Quote Originally Posted by garyk View Post
    I am (very) reliably told that the breather can be removed with the engine in the car....
    Thanks, I'll give it a go then.
    Think I'll have to take the EFI inlet manifold off and jack the engine up to the max because getting the 75mm bolt out is asking a lot, given the lack of room. Will see how it goes later in the week and report back
    Cheers, Marc.

    1987 CX GTi T2 Maikonics
    1972 SM 2.7 carb
    1972 DS21 EFI

  11. #11
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    I guess you don't need 75mm clearance. You don't need to pull the bolt completely out of the dome before the dome can be removed. Once you've disengaged the bolt from the block, the bolt and dome should be free(er) to move together.

  12. #12
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    I reckon some prising leverage in the shape of a flat screwdriver will also be needed because there is a good chance that rubber seal and the breather will be crusted together to the block!

  13. #13
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    Re you planning ahead on this Marc? Given how inaccessible it is, once you get it off, what do you plan to do? Is there perhaps a way to check for blockages with the dome attached? Maybe a piece of bent wire gently pushed into the top to probe?

  14. #14
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    Hello, if the crankcase breather is blocked, won't any blow-by vent via the pushrod tubes and out through the rocker box breather into the air filter?
    If you pull off the oil filler cap whilst the engine is running are you engulfed in fumes?

  15. #15
    Fellow Frogger! marc61's Avatar
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    I took one off a DS a very long time ago and found it completely caked up with crud. The blow by gases don't exit this way if its clogged up and I've noticed a few oil drips on the floor recently, so because nothing seems to be coming through it needs to be checked out.

    I did the same on my CX a couple of years ago and it was as clean as a whistle. My guess is they clog up if the car is low mileage and has done lots of short trips, not warming up fully so the vapours condense out. Vaguely remember a story of the rubber hose clogging up too.
    Cheers, Marc.

    1987 CX GTi T2 Maikonics
    1972 SM 2.7 carb
    1972 DS21 EFI

  16. #16
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    Quote Originally Posted by David S View Post
    If the crankcase can't breath and there is piston ring blowby, you may see oil leakage from the rear main seal. This is likely to be more of an issue on older engines with an asbestos rope seal and scroll, the rope seal not actually being tight on the crankshaft like a later rubber lip seal.
    Excellent thank you.

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