Distributor Rotor Stuck

Discussion in 'Gas Engines' started by C Cap, Jul 13, 2017.

  1. C Cap
    Joined: Apr 2017
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    Location: wisconsin

    C Cap Junior Member

    i removed the distributor cap on a Mercrusier 260 5.7L and cannot get the rotor off. Looking for tips on how to remove? I do not see any set screws, and wondering if the 'steel' piece comes off as well? i assumed just the top rotor piece came off, but in the new parts i recieved, the steel piece comes with too.

    Thanks in advance.
    C Cap
     

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  2. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    This is fairly common and it's corrosion that has filled the cavity in the bottom of the rotor, making it tight. Most of the time you can smack it a bit to free it up. On a few occasions I've had to break them off, but this can cause other issues, like pieces falling down into the distributor body. I've also used a heat gun to soften and expand the rotor a touch to free it up. Grab a small deadblow and "talk to it" easily. The first move I try with a stuck rotor is to place something under the contact arm and bang up against it, after a good dousing in WD-40 (from below). Once it's off, get the shaft clean and a very small amount of dielectric grease applied, so you don't have this issue again.
     
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  3. C Cap
    Joined: Apr 2017
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    Location: wisconsin

    C Cap Junior Member

    Thanks Par, good info! After doing more research, i found this service bulletin that was put out by mercruiser regarding stuck rotors...they suggested using a couple long screwdrivers to pry it up. But found it interesting that they suggested using loc-tite on the rotor before assembly....talked to a lot of mechanics today and it is the first any have heard of that.
    Thanks again.
    C Cap
     

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  4. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    I've never used thread locking compound on a rotor and wouldn't suggest it. This stuff is anaerobic in nature, requiring a really tight interface between the parts to cure. The expansion properties of the shaft and plastic would likely challenge this interface after the first start up.

    I've used the two screwdrivers trick previously, though a good shot with a deadblow is faster and more reliable. Just smack the top of it and the heavy corrosion that your photo shows will loosen up a bit.

    Lastly, get that housing cleaned up, as there's way too much oxidation going on. Also check that the vent isn't plugged, which is the usual cause for that much corrosion, of course assuming someone didn't use an automotive cap. Simply put, a new marine cap and rotor is in order. Automotive stuff isn't appropriate, will corrode (baddly) and can cause the boat to blow up too.
     
  5. Barry
    Joined: Mar 2002
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    Barry Senior Member

    Wrap a rag around the distributor rotor so no junk gets into the distributor.
    Drill a 3/8 inch hole through the centre of the rotor (but not into the shaft) an use a small gear puller to pull the rotor off
    While WD40 is great, a penetrating fluid has better capillary ability, you can pour a bit down from the top through the 3/8 hole and let it sit a bit
    Dow Corning 4 is the best dielectric grease that I have used. Silicone based,never hardens, great stuff
     
  6. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    A couple of good raps with a cold chisel will a also relieve the issue, at the expense of a new rotor, which at this point should be obvious anyway. I haven't had to actually break many rotors off, with a little force being all they need usually. Give it a good smack and see where you're at.
     
  7. Leonard Martinez
    Joined: Jul 2017
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    Location: Visalia, Ca.

    Leonard Martinez Junior Member

    I've had a similar issue with my chevy truck, and the solution was to pry it up with a screwdriver. If a steel piece comes with it I imagine it has a screw to secure that part. Might as well replace them while it's opened up.
     
  8. BaylinerBryan
    Joined: May 2018
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    Location: Euclid

    BaylinerBryan New Member

    Great post, I'm having the same problem with the rotor on my 4.3 engine. Just bought the boat last year and wanted to do a full tune up this year, everything was going smooth until I got to the rotor, this thing will NOT come off!!! I'm going to give it a few cracks with a hammer and try to pry it off with screwdrivers. Thanks again for the great advice and information!
     

  9. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Light taps at first, try to remove, then more taps. They come of easy enough, but sometimes require some "convincing".
     
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