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Hot!Fh680D bent push rod(s)

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lester1
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2018/05/23 19:59:24 (permalink)
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Fh680D bent push rod(s)

While mowing my lawn 3 weeks ago I heard a weird (pht pht) like running over a plastic bag - if you know that sound, then I had 1/2 power on the mower. I searched the internet and it sounded like it could be coil wires so I replaced both and it still had 1/2 power. I guess I should have checked the spark first. A friend came over removed the valve cover and expossed the 2 bent push rods. also the exhaust valve liner was pushed up and the oil seal was destroyed. I ordered a new head and parts from Jacks and installed them yesterday. Started the mower and did a test cut for about 1 minute ran well - I was pleased with my work-first time at doing motor work, then as I was putting the mower away there was a small pop like a very small backfire just before I shut it down. I thought that did not sound too good so I started it up again and -you guessed it only 1/2 power. When i opened up the valve cover my intake push rod was bent and the exhaust rod was out from under the rocker arm. I am not sure what caused this other than maybe I did not set the valve gap correctly. So my question is- When I set the gap at TDC at 0.006" do I set the intake at the same time as the exhaust so they are both the same when the crankshaft is at the same place or do I rotate the engine and set the exhaust when the intake is open.? I assume there is a time when both are closed and a time when only one is open and the other is closed. Is TDC a time when they both should be closed? Also I set the gap at 0.004" but I found that the gap should be 0.006"-would that make a difference?  

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    AVB
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    Re: Fh680D bent push rod(s) 2018/05/23 20:59:39 (permalink)
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    Actually per service manual it .004-.006 so that should be fine if you followed the following instructions.

    And you said I too don't what may have cause this as I just got a Kawasaki with intake push rods bent and both exhaust rocker out of place since the locating pins are broken off.
     
    lester1
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    Re: Fh680D bent push rod(s) 2018/05/24 22:38:58 (permalink)
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    I purchased new push rods locally and paid a lot more than on Jacks. I installed the new push rods and changed the rocker arms as well - the previous time I did not put the new rocker arms in, I was very careful about setting the gap on the valves and found a kawasaki site that said the gap should be 0.006" so I used that gap and checked and double checked and triple checked the gap. The mower started up and ran flawlessly all afternoon and I cut some pretty long grass - this is only my second cut this season due too a lot of rain in March and April which made the ground too wet to drive on and then on my second mow I developed this problem and that was 3 weeks ago so three weeks of growth plus one area had not been cut yet at all so it is over three feet tall. The mower cut it all but I will have to finish the rest when it dries up as we are expecting more showers tomorrow. I am using John Deere 737 mower that is 10 years old, I have had to replace the electric clutch twice and the front and rear oil seals on the crankshaft and now this cylinder head and related parts but it is a really solid mower.
    AVB
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    Re: Fh680D bent push rod(s) 2018/05/25 04:16:44 (permalink)
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    Tnx for the update...Now I know to watch out the rockers.
     
    I usually put on upgraded clutches on my customer's mowers and I too have seen a lot oil seal failures on the Kawasaki horizontals. A pain to deal with as some mowers that engine has to come out just get to the fan shroud off.
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