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John Deere 400, Kohler engine problem

3405 Views 9 Replies 4 Participants Last post by  dave_r
I just acquired a John Deere 400; and it has relatively low hours. Actually the mower deck looks almost new; as the machine had a snow blade on it, when I got it. Even at that it had not been used in long time.

Tractor look good and runs good; until you try to mow with it. To rule out the mower deck, I installed another 60" mower that I used on another JD 400.

Somebody had been working on this problem and obviously, could not fix it.

Problem: K-532 runs at idle fine, actually a very quiet engine, for a K series. But when you mow and come to an area with heavier grass, and the governor should kick in; it just doesn't run right. It seems to bog down.

New coil and tested good too, new spark plugs, new point to .020", plug wires good. New ethanol Free gas. Compression good. It did have a bad coil and one bad spark plugs wire (completely open) when I bought it. So it was running on one cylinder. Previous owner obviously didn't diagnose the problem correctly and started messing with the governor. You can see the finger prints and dust wiped clean on the parts they touched. So something is messed up now.

Somebody has been adjusting the governor to carburetor linkage. They have not gotten into the governor (still dust on the governor bolts).

I checked all the Kohler manuals, and nothing is printed on how to adjust the above mentioned rod. I did take a rod off of another know good engine to try, it didn't make it any different. I will say the replacement rod was 3/8 of an inch shorter.

Carb is set to specs, air filer is clean; but it seems to go rich when the governor kicks in.

I feel this is the reason for the low hours and not being run in years.

Any ideas?

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I can tell you this much, I had a 420 with an Onan that had been "Worked" on by the PO and he had the wrong length governor rod on the carb. No matter how much I played with it, I could not get the governor to work. Boomer sold me the correct length rod and that solved the problem. One thing I found out on the Onan is that there is a preload on the rod. It is not just an A to B type length. The preload is what makes the governor respond at the correct time. Research it and find out the correct length rod. I used coat hanger wire and made different lengths and realized that length was the critical factor. There is a guy I know who is trying to sell two 400's and he might be able to tell you the correct length on his 400. If you PM me I will give you his number.
Moto, I cleaned out my message box in case you want to send me one.
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