Wankel Rebuild

  1. Lewis_RX8

    Lewis_RX8 Member

    Messages:
    375
    Location:
    Scotland
    So to make a long story short i got a rebuilt Mazda 13B wankel engine from evil bay (first mistake) to swap out for the one in the rx8 at the moment. It held coolant pressure and oil pressure fine on the bench however when it was put into the car it was nearly impossible to start , misfired and had extremly low compression.

    So the old one was put back in and now time for the teardown to find the fault in my " Rebuilt " engine.

    First of all put onto the engine stand with a home made adaptor plate that can be seen painted grey.
    Drained all fluids off to stop them coming out later at more inconvenient times.

    upload_2020-6-16_23-32-40.png

    Then time for another home made tool , to remove the flywheel from the taper.

    upload_2020-6-16_23-34-27.png

    After that was removed it was down to a bare block and a tiny engine for the power it produces.
    The 18 bolts holding the block together where numbered and removed in the right order.

    upload_2020-6-16_23-37-33.png


    Then down to the first rotor and housing ( Think piston and cylinder)

    upload_2020-6-16_23-38-50.png

    And the fault with the compression of the engine became obvious instantly , The apex seals which seal the corner of the triangle rotor to the housing where put in back to front :o

    You could easily see daylight through the seals when they where supposed to be holding 8-7 bar for combustion.

    So the cowboy builder that built then shelled out for good condition parts brand new apex seals from mazda at £350 but then put them in the wrong way.

    Here is a close up of the apex seal that "should" push agaisnt the housing wall and seal with the pressure from the spring behind it.

    upload_2020-6-16_23-47-50.png

    As the seals where in back to front the corner piece ( where that triangle gap at the bottom is) was not in properly and may aswell have had no seal there with a gap that big.


    It was then fully stripped down to parts and glad to say i am quids in on this engine for how much it cost as it has alot of brand new or good condition parts , seals and gaskets.

    upload_2020-6-16_23-48-29.png

    upload_2020-6-16_23-49-24.png

    This will be getting some other parts from a old engine where it needs it and then rebuilt.

    So the moral of the story is.

    If you want a job done right do it yourself.
     
  2. gaz_moose Member

    Messages:
    988
    Location:
    tamworth staffordshire
    its worth making a tray that sits on the engine stand to catch the fluids that drip out.

    Also good result on the simple fix.
     
  3. Ashley Burton

    Ashley Burton Member

    Messages:
    3,971
    Location:
    Northamptonhire
    They're a unique design, Not the most reliable I get the impression from many though
     
  4. tom2207 Member

    Messages:
    1,607
    Location:
    uk northern ireland
    so will you get way with reversing the seals , or are they now damaged ?
     
  5. Lewis_RX8

    Lewis_RX8 Member

    Messages:
    375
    Location:
    Scotland
    Could do with that , More of a decent fix rather than just tubs underneath

    Very unique design very interesting engineering going on in that engine however yes the reliability is rumoured to be not the best however a few bad engines ruined the bunch i believe. My old one is still going strong 70k miles from factory while not being maintained the best in its past life.

    And i dont think the reputation is aided by rebuilders like the one i experianced :vsad:

    Seals are still brand new , 5.3mm thick which is how they come from mazda. O rings and gaskets may be reuseable aswell as they are "racing type" so the engine can be pulled apart then put together again with the o rings not stretching.

    Quite pleased with the seals , Saved me from the stealership bill :laughing:
     
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  6. Lewis_RX8

    Lewis_RX8 Member

    Messages:
    375
    Location:
    Scotland
    believe @barking mat was interested in theses. Will wait for you to catch up with the roots diesel ,,,, after the house and after the roundtuit,,,, :whistle:
     
    barking mat likes this.
  7. fizzy Forum Supporter

    Messages:
    6,264
    uk
    I LOVE the RX8. Much nicer to drive than the 350 and 370z. I have had all 3 on long term hire in the past. The RX8 is a proper drivers car. Shame the engines are so fragile.
    I remember a mate had the RX7 turbo. He wasn't the sharpest tool in the box sadly. He said the car was awesome but the steering was weird - like flying a plane. I had a go - the idiot had been driving around with the steering column adjuster loose - yup just like the yoke on a plane :laughing:
     
  8. seanc Member

    Messages:
    230
    northants
    I purchased a cheap rx8 a while back as the engine was on its way out, trouble starting when hot, Had a bit of fun in it until it didnt want to play anymore :)
    Looked at rebuilds but couldn't really be doing with the fuel economy and general high running costs so I am currently mid way through swapping a k20 into it.
    Im sure im not to popular with the rotary crowd but never mind
     
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  9. frank horton

    frank horton V twins are great but 4"s rule.........

    Messages:
    1,848
    Location:
    Soon 2 B Crete
    Bought a MK1 RX......It came in with a trashed engine......
    Put in an Essex V6 Ford engine n box.......
    Not as sweet to drive.....
    Still a nice car....wish I had it now.......
     
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  10. frank horton

    frank horton V twins are great but 4"s rule.........

    Messages:
    1,848
    Location:
    Soon 2 B Crete
    Whats a K 20
     
    Lewis_RX8 likes this.
  11. Haz87 New Member

    Messages:
    4
    Location:
    Essex
    Honda engine. Came in the old (early 2000) Type-R's iirc
     
    Lewis_RX8 likes this.
  12. Greeves246 Member

    Messages:
    207
    Location:
    Cheshire uk
    NSU RO80 often had the rotary engine replaced with a conventional engine as an adaptor plate was commercially available. Nobody was prepared to work on the Wankel at the time. Beautiful car, not seen one for many years even at shows.
    As an aside, the Norton rotary engines were built under almost surgical conditions at Shenstone.
     
    ronan, fizzy, Lewis_RX8 and 2 others like this.
  13. 8ob

    8ob Forum Supporter

    Messages:
    5,650
    Location:
    moscow on thames
    Thats a blast from the past, a friend of mine Dave "the rave" Thomas used to sell the v4/v6 Ford conversions for the RO80, he sold hundreds of them complete with new Ford engines, the wankle at the time was always in trouble.

    Bob
     
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  14. Brad93

    Brad93 M J B Engineering

    Messages:
    8,518
    Location:
    Essex
    How do you know, the bolts which you numbered, were put back the correct way by the cowboy builder
     
    Lewis_RX8 likes this.
  15. 8ob

    8ob Forum Supporter

    Messages:
    5,650
    Location:
    moscow on thames
    I think its more a sequence thing Brad.

    Bob
     
  16. pedrobedro

    pedrobedro Man at Matalan

    Messages:
    10,384
    Location:
    CX Derbyshire
    Friend of mine had one in bright orange, the engine was swapped out for a Ford V4 usually. That's what we fitted in his as you had to park it at the top of a big hill to start the rotary engine.
     
    Lewis_RX8 likes this.
  17. slim_boy_fat

    slim_boy_fat Forum Supporter

    The Wankel is a brilliant design concept, flawed [esp on the NSU days] by poor rotor-tip seals.
     
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  18. fixerupper

    fixerupper Member

    Messages:
    1,617
    Location:
    Crete Greece
    Interesting thread ..I've never seen inside a rotary engine in the flesh or in a photo ...only drawings...
     
    zx9, moose, DavidL and 3 others like this.
  19. Lewis_RX8

    Lewis_RX8 Member

    Messages:
    375
    Location:
    Scotland
    Yes bob is correct , most of the bolts are the same does expect 3 that have diffrent bolt heads the numbering is just to let the pressure off evenly i suppose.

    Some arent a fan of changing the engine however far better than scrapping a nice car just because the engines went bad. Most of them are quite interesting saw someone put a cummins diesel in one :laughing:
     
  20. ranchero Member

    Messages:
    114
    Location:
    southampton
    my son had a rx8 drank more petrol than my american v8 it drank a lot of oil as well
     
    Parm, Lewis_RX8 and Pigeon_Droppings2 like this.
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