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  1. #1

    Default The rotor on my distributor is not turning when cranking

    When i crank the motor, the rotor is not turning. I pulled out the distributor and it moves freely. what is my problem here? Am i going to have to check inside the motor now? How do i do this? I am assuming the gear must be damaged?? Whats my first step here?

  2. #2
    Join Date
    Oct 2006
    Location
    Sherwood Park, Alberta, Canada
    Posts
    393

    Default Re: The rotor on my distributor is not turning when cranking

    What type of engine are you working on?
    Bert

  3. #3

    Default Re: The rotor on my distributor is not turning when cranking

    ok so i pulled the distributor out and again cranked the motor. The little gear that I can see in there is not turning, therefore obviously not turning the rotor. How major of an issue is this? what would this part be called?

  4. #4

    Default Re: The rotor on my distributor is not turning when cranking

    mercruiser 165 3.7L

  5. #5
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    5,570

    Default Re: The rotor on my distributor is not turning when cranking

    a 3.7L merc 165 should be an inline 4 cyl. since the distributor turns free, I'm guessing the "little gear" you refer to is the distributor drive gear on the camshaft. that means the timing chain is broken or one or more of its gears are damaged. Major? let's say it is necessary for the engine to run...

  6. #6

    Default Re: The rotor on my distributor is not turning when cranking

    When I first rebuilt my 470, while doing the cam seals, I noticed that the cam sprocket keyway and camsprocket had heavy wear. Maybe sheared keyway, maybe broken timing chain. If the cam is not spinning you have no chance of running. I ditto makomark. Need to get the timing cover off, remove coil wire, keys, hand rotate engine and see what's going on in there. good luck, Tom

  7. #7
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
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    7,230

    Default Re: The rotor on my distributor is not turning when cranking

    If the distributor "driven" gear is not damaged, remove the valve cover and check to see if the rocker arms are being actuated.
    Or..... pull several spark plugs and see if the cylinders are building pressure.
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  8. #8
    Join Date
    Jan 2010
    Location
    Farmington, Ar, usa
    Posts
    27

    Default Re: The rotor on my distributor is not turning when cranking

    Check to see if the pin in the distributor gear is still there or sheared off

  9. #9
    Join Date
    Mar 2009
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    Default Re: The rotor on my distributor is not turning when cranking

    Quote Originally Posted by speakrdude
    Check to see if the pin in the distributor gear is still there or sheared off
    Jim, I'm somewhat embarrassed for having not mentioned that myself.

    You may have nailed it!


    .
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  10. #10
    Join Date
    Dec 2006
    Location
    Chaumont Bay, N.y., USA
    Posts
    4,203

    Default Re: The rotor on my distributor is not turning when cranking

    Quote Originally Posted by Pbdy Jr View Post
    When i crank the motor, the rotor is not turning. I pulled out the distributor and it moves freely. what is my problem here? Am i going to have to check inside the motor now? How do i do this? I am assuming the gear must be damaged?? Whats my first step here?
    Ayuh,... Pull the drive, then the Motor,...

    Yer goin' in Deep to fix it....
    Any Grease is Better,... Than No grease at All....

  11. #11

    Default Re: The rotor on my distributor is not turning when cranking

    Check that pin folding the dissy gear on. (It may still be in there and gear seems solid, but it still may be broken and gear may turn on shaft with a little effort). If it's good, then pull the plugs and valve cover, set the timing mark to Top Dead Center ("0" degrees), checking to see it if the valves open and close while you turn engine over by hand. If the valves don't move, cam isn't turning and the timing chain / gears are gone. If the valves do move, see if the #1 cylinder has both valves closed (Note: If valves are not closed, could be 180 degrees out, so turn engine by hand one full rotation till TDC again and recheck). If both valves on #1 not closed in either TDC, cam timing is kaput and major surgery is instore to check the cam drive chain / gears.

  12. #12
    Join Date
    Mar 2009
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    Portland, Oregon,
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    7,230

    Default Re: The rotor on my distributor is not turning when cranking

    Merc's 3.7L is their own 470 engine design, so I am assuming that we're all talking about the Merc 470.

    Quote Originally Posted by 04fxdwgi View Post
    Check that pin holding the dissy gear on. (It may still be in there and gear seems solid, but it still may be broken and gear may turn on shaft with a little effort).
    Good point.

    If it's good, then pull the plugs and valve cover, set the timing mark to Top Dead Center ("0" degrees),
    Since his distributor is not turning, I think that he could forgo this step.

    checking to see it if the valves open and close while you turn engine over by hand.
    Agreed. This will tell him much more.

    If the valves don't move, cam isn't turning and the timing chain / gears are gone.
    Either that, or the crankshaft sprocket key has been sheared off.

    If the valves do move, see if the #1 cylinder has both valves closed (Note: If valves are not closed, could be 180 degrees out, so turn engine by hand one full rotation till TDC again and recheck). If both valves on #1 not closed in either TDC, cam timing is kaput and major surgery is instore to check the cam drive chain / gears.
    No disagreement, but again, he is not seeing any distributor shaft rotation.
    The 470 camshaft's distributor "drive" is up front and is positioned ahead of any cams. Unless this camshaft could snap just ahead of this gear, I'd say that it pretty much rules out a broken camshaft.

    The sixth cam back is the fuel pump cam. If you are seeing fuel pressure, I'd have to suggest that the cam shaft is rotating.





    Look at the distributor gear spring pin, and look for rocker arm action first.
    That's going to tell more than most anything else.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Merc 470 camshaft.jpg 
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    Last edited by RicardoMarine; 04-21-2013 at 08:37 AM.
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  13. #13
    Join Date
    Jul 2008
    Location
    Northboro, Ma, USA
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    3,451

    Default Re: The rotor on my distributor is not turning when cranking

    """""""ok so i pulled the distributor out and again cranked the motor. The little gear that I can see in there is not turning,""""""


    This is the result of what ever is wrong............

    two things, either broken timing chain/sprocket or broken cam shaft.............

    One caviot......I am not sure how the gear is attached to the cam shaft but if it is a pressed on gear it may have come loose. Other than that we need to know if the cam is spinning or not before any theorys can be discussed......jmho

  14. #14
    Join Date
    Mar 2009
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    Portland, Oregon,
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    Default Re: The rotor on my distributor is not turning when cranking

    Just a friendly FYI...... the cam drive on Merc's 470 engine is chain and sprockets....... not gear driven.

    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  15. #15

    Default Re: The rotor on my distributor is not turning when cranking

    OK so in fact, the camshaft is not turning. im thinking its a gear issue. When I turn the impeller manually, the distributor turns and the valves move as they should. but not when cranking the motor. i believe my motor has timing gears not a timing chain.. anyone want to tell me the quickest way in to see this??

  16. #16
    Join Date
    Jul 2008
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    Northboro, Ma, USA
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    Default Re: The rotor on my distributor is not turning when cranking

    The post before yours shows what you have Post 14........This motor has a timing chain not timing gears. the gear refered to is the one on the cam shaft that turns the dstributor........

    What impeller are you refering to????????????

  17. #17

    Default Re: The rotor on my distributor is not turning when cranking

    Hi Guys dont want to act dumb but how do I add a new post..... sorry in advance

  18. #18

    Default Re: The rotor on my distributor is not turning when cranking

    or a new thread

  19. #19
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    Default Re: The rotor on my distributor is not turning when cranking

    Quote Originally Posted by kghost View Post
    What impeller are you refering to????????????
    The Mercruiser Engineers designed this engine to drive the engine circulating pump impeller from the front of the camshaft.

    In this photo, the next item to be installed will be a cover...... of which is actually part of the engine circulating pump housing.
    This cover seperates the oil wet area of the timing chain from the ethylene glycol side of the cooling system.

    A special and problematic seal keeps oil AFT of this area, and E/G FWD of this area.
    The impeller installs on the front end of the camshaft.

    Lastly installed, would be the very front cover.

    Last edited by RicardoMarine; 04-22-2013 at 08:11 AM.
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  20. #20
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    Jul 2008
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    Northboro, Ma, USA
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    Default Re: The rotor on my distributor is not turning when cranking

    Look at this for a new thread..

  21. #21
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    Jul 2008
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    Default Re: The rotor on my distributor is not turning when cranking

    Quote Originally Posted by RicardoMarine View Post
    The Mercruiser Engineers designed this engine to drive the engine circulating pump impeller from the front of the camshaft.

    In this photo, the next item to be installed will be a cover.
    This cover seperates the oil wet area of the timing chain from the ethylene glycol side of the cooling system.

    A special and problematic seal keeps oil AFT of this area, and E/G FWD of this area.
    The impeller installs on the front end of the camshaft.



    FYI, I am not the one who needs a lesson in merc 470 design just so ya know, Been there done that soup to nuts on these many times.
    My question was to the original poster.

  22. #22
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    Mar 2009
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    Default Re: The rotor on my distributor is not turning when cranking

    Quote Originally Posted by kghost View Post
    FYI, I am not the one who needs a lesson in merc 470 design just so ya know, Been there done that soup to nuts on these many times.
    My question was to the original poster.
    Kghost, there was no offense intended with my explanation.
    You did ask which impeller he was refering to..... correct?

    FYI..... I was simply pointing this out after having made the assumption that you did not know.


    For anyone else...... there's only one impeller that could be used to rotate the camshaft while the front cover is removed, and only if the Timing Chain was in-operative.




    .
    Last edited by RicardoMarine; 04-22-2013 at 08:13 AM.
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  23. #23

    Default Re: The rotor on my distributor is not turning when cranking

    Ok so i may have a timing chain issue. But i cant get the impeller off to remove the cover. Do i need to remove the stud? Its completely stripped. Or just turn the impeller clockwise? When i try this it only turns the camshaft

  24. #24
    Join Date
    Mar 2009
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    Portland, Oregon,
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    Default Re: The rotor on my distributor is not turning when cranking

    Maybe we should stay with your new thread. I posted a few links in for you. Hope it's helpful.
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  25. #25

    Default Re: The rotor on my distributor is not turning when cranking

    Rick, I also failed to mention the pin on the distributor shaft gear. That would seem to be one of the easiest routes. Anyway, I was wondering if Pbdy Jr had removed the distributor prior to this problem? The reason being that could it be possible that he has not installed the distributor all the way down into the oil pump drive? If the pin is intact, the gear on the distributor is undamaged, the gear on the cam is undamaged , the distributor has been carefully fit down into oil pump drive and the shaft has been rotated carefully as to allign both gear sets then I am still leaning towards the front cover. Valve cover removal was another good suggestion to see if valve train is operating properly, ruling out a broken camshaft. In my case while rebuilding, the camshaft sprocket or gear or whatever you want to call it was very loose on the front of the cam shaft just inside the front seals. The keyway was so hammered that the cam sprocket had a few degrees of free play or rock back and forth. In my case, I replaced camshaft,gear,key. The timing chain on these engines look pretty bullet proof. Not sure about problems with timing chain tensioner? It is a pretty heavy duty application. Have any of you guys ever replaced a timing chain on the 470's that actually broke? Just wondered, that's all. Only one more thing that comes to mind: Take the cap and rotor off the engine, remove plugs, coil wire and keys and hand rotate engine from the front of the engine clockwise. Look to see if the distributor is turning if all other things above are not the case. A guy on another site apparently got the wrong rotor for his 470 and it stripped the inside of the rotor right out. I know, can you imagine? Probably not the case. Anyway, anything is possible so I try not to assume anything. You know how that goes! HAHAHA! Oh yeah, one more thing, maybe take a flashlight and look down into block where the distributor gets installed and carefully look at the camshaft distributor drive gear for damage. If someone tried to force the distributor down without finessing the two gears together ever so carefully and feeling it slide together then it could be possible that gears are damaged. Not saying that is the case but a possibility. Finally, without the camshaft drive gear turning the distributor, you are not rotating the oil pump. Without the oil pump, no oil pressure. You can pretty much figure out the rest. Best of luck always, Tom
    Last edited by 1973 Browning Marine; 04-22-2013 at 09:20 PM. Reason: typo

  26. #26
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    Mar 2009
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    Default Re: The rotor on my distributor is not turning when cranking

    Tom, see post #23.
    He can turn the circulating pump impeller, make the rocker arms move, and with no crankshaft resistance.

    .
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  27. #27

    Default Re: The rotor on my distributor is not turning when cranking

    Rick, you got me scratching my head now! lol Broken crankshaft sprocket keyway? Broken timing chain! Right?
    Last edited by 1973 Browning Marine; 04-22-2013 at 09:32 PM.

  28. #28

    Default Re: The rotor on my distributor is not turning when cranking

    my iimpeller was ridiculously stuck. Nothing worked. Stud head was stripped. Had to break the aluminum impeller off. Opened cover and seen everythinghooked up...... But the gear spun freely on shaft. Aftet removal i found the keyway out of place and not in the slot on the gear. Now to order the parts and find my next problem. Thsnk you all

  29. #29
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    Mar 2009
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    Default Re: The rotor on my distributor is not turning when cranking

    Quote Originally Posted by Pbdy Jr View Post
    Aftet removal i found the keyway out of place and not in the slot on the gear. Now to order the parts and find my next problem.
    It may not be that simple.
    You'll want to find out what caused the key to slide out of position in the first place.

    .


    .
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  30. #30
    Join Date
    Jul 2008
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    Northboro, Ma, USA
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    Default Re: The rotor on my distributor is not turning when cranking

    Ya like hitting a rock

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