Plastic? On a Dipstick?

Kanzaki Dipstick Transmission oil inspection time: See that little yellow ring on the right? Well it is supposed to be attached to the yellow wing nut. The yellow plastic wing nut. This is a diesel transmission, and they used a plastic wing nut on the dip stick?

DipstickThis looks like something designed for a lawn mower. The fracture occurred where the threads begin, where the o-ring seats — where compression turns into shear. This apparently is a common problem based on searching the cruising forums.

So now, we have a new one on order, and I have to extract the fractured piece in such a way as not to get any fragments in the transmission. This is where plastic may work in our favor. A slot screwdriver firmly pressed downward while twisting should do it.

Geez, plastic

5 responses to “Plastic? On a Dipstick?

  1. I got tired of replacing the plastic dip stick cap/tube assembly every 2-3 years. Seems no matter how careful I was, the plastic cap/threaded portion eventually shears off. I suspect that the plastic is slowly degraded by contact with the transmission oil combined with heat.

    So, I made a replacement out of anodized aluminum that can have the existing Yanmar dipstick tube inserted into it or it comes with a new dipstick tube. See the attached pictures.

    The one shown is for a Yanmar KM35A transmission and is a direct replacement for Yanmar part 177070-62450. I have since verified that this is the correct part number for the dip stick on a KM35A. Some had posted in this group earlier that PN 177074-02454 was the part number for the KM 35A dipstick but that turns out to be incorrect.

    Yanmar part 177074-02454 is the dip stick for a KM3A1 or KM4A1 transmission and it is .875″ (7/8″) longer than the 177070-62450 dipstick for the KM35A.

    I am offering these hard annodized aluminum versions for sale both as a complete assembly (YM1001-01) to replace the Yanmar part 177070-62450 for the KM35A and similar and also just the cap (YM1001-00) that can be used with any existing Yanmar transmission dipstick that has the same type of hollow dipstick tube. So you can purchase just the Cap only (YM1001-00) and take the hollow tube out of the original Yanmar plastic cap (just push the tube up into the cap and a plastic insert will pop out of the Yanmar cap to allow the tube to be removed) and put it into my aluminum cap and no more plastic cap problems.

    Part number Description Price
    YM1001-00 Dipstick Cap only to replace the plastic cap
    Can be used with original Yanmar dipstick tube $75
    YM1001-01 Dipstick/tube assembly for Yanmar KM35A (replaces 177070-62450) $85
    YM1001-02 Dipstick/tube assembly for Yanmar KM2P(-1) and KM3P (replaces 177088-02451) $85
    YM1001-03 Dipstick/tube assembly for Yanmar KM5A (replaces 177074-02500) $85

    Yes, I know – more than twice the price of the Yanmar part but it will be the last one you’ll ever buy and you won’t discover a bilge full of transmission oil while you are cruising because the plastic part broke.

    I can be reached via email at or by telephone 310-736-4376

    Bob Atkins
    Cariblue Marine

  2. Now you’ve got me worried! This is going to make me put off the next transmission fluid change even longer.

  3. Yanmar? Yes I managed to break ours off too. A shame since the rest of the engine is beautifully made and I love it! Great engine!

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