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  1. #1

    White Plastic Round Part on Camshaft Sprocket?

    Anybody know what the function of the off-white nylon or plastic round part is that is attached to the camshaft sprocket/gear on 4-tec engines? Mine got chewed up and my timing chain no longer has tension, and I think the cam is out of time now. Fortunately, didn't seem to hammer the valves, so must only be off a tooth or two.

  2. #2
    Fast & Loud meeper's Avatar
    Join Date
    Jul 2005
    West Grove, PA
    if you mean the tan thing that is related to the crank case ventilation system or TOPS, it is irrelevant to the chain tension so I'm confused about your statement

  3. #3
    Maybe the chewed up ventilation part is unrelated to suspected timing problem, but my timing chain is loose, the guide on the back side of the timing chain is damaged a little, and the timing chain is sloppy loose. I'm going to replace the ventilation piece, the backside chain guide, the tensioner chain guide shoe, and the tensioner and check the timing. It quit running, after running fine, compression had dropped to 35 psi on all three cylinders and BUDS showed a cam position or timing fault. When we took the valve cover off, we found the ventilation part had fallen off the cam sprocket, and timing chain sloppy loose, etc.

  4. #4
    it holds the steel washer that seals onto the vent valve o-ring.
    what year is your ski, it might not need it, ive seen a few pre 06 engines with that on the cam gear that didn't end well, without the rear vent valve they can fall out into the chain gear.
    yours might have a broken piece jamming the tensioner and a bit of the plastic rolling through the gear and chain will alter the timing

  5. #5
    '07 215 Wake. The thrust washer had fallen into the PTO case and was on the bottom. The yellow nylon round piece was all chewed up, mostly in the head laying below the cam sprocket, but a couple other pieces scattered elsewhere inside the valve cover. A black rubber grommet-like ring was also laying below the cam sprocket inside the valve cover. The back side timing chain guide was damaged and loose, the timing chain was a little loose, too. I figured I'd replace all the parts, including a new tensioner, both chain guides, black grommet, yellow round plastic thing, then check the timing in case it might have jumped a tooth. Does that yellow thing attach somehow to the cam sprocket?


  6. #6
    RXP 260 X Short Course Veteran RXP244's Avatar
    Join Date
    May 2007
    Auckland, New Zealand, New Zealand
    Are you splitting the cases and doing a complete rebuild? That is the only way you will be able to change both chain guides. I would be breaking that engine down and at least also checking the teeth on the crank sprocket for damage.

  7. #7
    Already have the PTO enclosure removed. Just waiting for parts to all come in. Unfortunately, I'm getting too proficient at pulling engines out of Seadoos, if you know what I mean!

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