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Hot!Kohler Confidant ZT740 Rocker Arms lash adjusters backing off.

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StangManOK
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2019/11/16 16:44:41 (permalink)
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Kohler Confidant ZT740 Rocker Arms lash adjusters backing off.

Good afternoon All,

BACKGROUND: I have a 2015 Badboy CZT 54" zero turn with a Kohler Confidant ZT740 engine. I bought the mower used about a year ago (2018) from a local dealer. The sales person I spoke with said this mower was used by the owner's brother to mow his small average. The hour meter was around 160 hours. The chassis seemed to have an appropriate amount of wear and other than a small repair done to the hole knocked into air filter housing the engine seemed to be reasonably new from the outside. I now have my doubts as to the accuracy of the hour meter and suspect it was unhooked at times. I'm making this assumption on the number of problems I've had with the engine. Maybe the dealer was on the up-and-up and I want to think the best of people, but I have some doubts. Moving on. :)

Issues: The starter Bendix seemed to be worn out shortly after purchasing the mower. As soon as the first cylinder fires it would disengage the starter pinion and wouldn't continue cranking through the ignition of the 2nd cylinder. I tried to be cheap (when will I learn?) and only replaced the bendix which fixed the problem only temporarily. I've since replaced the entire starter and the problem has went away.

The continuing and most frustrating issue is the rocker arms backing off and subsequently the valve lash increases until the pushrods can become free of the rocker arm socket the pushrod rides in. The first time it happened was on the right cylinder, I think that's #2? For the sake of this conversation I'm going to refer to the left as #1 and right #2 with respect to your normally seated position. I disassembled the #2 side and inspected the pushrods, checking for straightness and wear. Checked the rockers and lash adjusters, pivots and studs. All seemed fine. I cleaned everything up and reassembled. I set the lash to .005" and torqued to spec. Everything ran fine for ~20 hours and the issue happened again on #2. Repeated the previous repair paying extra close attention to torque specs and cleanliness.

In another ~10 hours the #1 cylinder did the exact same thing except that I found the rocker arm stud had backed out as well.

It has been about 10 hours since the last time I repaired #2 and has just done it again.

I'm tempted to put some loctite on the adjusters to hopefully keep them from backing off. Has anyone else experienced anything like this? I've been building and repairing engines from small glow fuel, lawn equipment, ATv and motorcycles, and lots of car/truck engines for 25 over years and have never had a repeating issue like this.

Sorry for the really long post. I wanted to share as much pertinent info as possible.

Thanks!

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    AVB
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    Re: Kohler Confidant ZT740 Rocker Arms lash adjusters backing off. 2019/11/16 17:36:33 (permalink)
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    I haven't had any problems with the one I set the valve clearances on. Are you torquing the set screws to 70 in/lbs? Of course, once you do torque the set screws; the clearances needs rechecking as they can change due to the tension.
    firehose
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    Re: Kohler Confidant ZT740 Rocker Arms lash adjusters backing off. 2020/05/28 19:56:20 (permalink)
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    I have a craftsman gt5000 Kohler engine cv 725s. somehow, the top valve push rod is bent. I was mowing and it started to get noisy. I checked the oil, its good. removed valve cover and found bent push rod on the upper right. the above post mentions set screws. I only find center bolts thru the rocker. I do not see any way to set valve clearance.
    AVB
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    Re: Kohler Confidant ZT740 Rocker Arms lash adjusters backing off. 2020/05/28 21:15:27 (permalink)
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    That the CV725 uses hydraulic lifters and are self adjusting.
     
    You probably got a valve guide that has moved which prevent the valve from fully opening therefore the push got bent. Just a guess.
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