Annoying clatter from 1650
 

My 1650 makes a loud clattering noise that you would swear was a rod about to come flying out through the hood. But the engine runs perfectly at wot, will pull my brinley plow and just recently pushed 10 yds of topsoil all over my yard. Doesn't run hot, doesn't use oil, etc. I've looked everywhere I can see for some sign of interference but can't see anything hitting. The clatter follows rpm so it's either in the engine or it's the engine shaking enough to hit something. Any ideas? Has anyone else had this problem? Tia
Dave

It isn't any engine tin that is loose is it?

How are the ISO mounts? Can you wiggle the engine around in the frame?

Drive shaft possible warped? My 1050 can make some noise from time to time because I need to replace the drive shaft, its got a slight warp in it.

Before I did anything to my 1450 was smooth wide open only.
So far I've reduced noise by:
replacing iso mounts/cradle mod
bending/fastening upper grill/headlight screen
welding cracked muffler
bolting engines tins together properly
putting rubber edging on the hood
adjusted idle lower

Now, just off idle it still bounces a bit and rattles the hood a little. At idle and mid on up it runs smooth. Smooth being relative, its a big single cylinder, its going to move around, key is to have move quietly.

Bill

The cap/dipstick on my 1200 was loose and made the same noise.

My old 1450 had a missing mm iso on th rear along with a tweeked driveshaft and it was horrible. Replaced the shaft and the little bushing on the fk ywheel side and it helped a lot

piston slap. drain some oil and look for metallic (aluminum) in the oil.

It doesn't sound tinny, and I've laid under the darn thing with the engine running and can't see anything moving or touching. The engine does shake a bit but then that's more or less normal isn't it. I plan on taking a harder look at the iso mounts and I'm going to take that aluminum muffler box apart to check that out.
Piston slap, man I hope it isn't that. But with a piston that loose in the bore wouldn't it be burning oil? All good things to look at. I'll probably end up pulling the engine. The driveshaft seems to be a new one, looks like stainless and is very snug fitting. The rag joints look good, too. Thanks again everyone.

But with a piston that loose in the bore wouldn't it be burning oil?


No. Rings could be well seated, and still get piston slap. Usually that will improve when up to operating temp, has been my experience in a couple of cars.

well i just rebuilt my engine in my 1650 and did abunch of general work up front. i fired it up today and had some anoying rattles still so far this is what i found and the hood and grill is not on yet. my throttle cable was hitting the hydro linkage arm. i put some plastic split loom over that. i still had a rattle but when i pushed in on the end of the hydro lever it went away. well when i had things apart i took of teh link going to the spool valve and cleaned it all up. it seems all the gunk and rust was keeping it nice and tight. now it is free and is clattering around. i think i will throw some grease on it and it should quite it down hopefully.

Is the noise something new? If it is I'd start looking for things that are loose and remove them one by one and see what happens. The other guys have given you some good ideas to check.

Yep, lots of things to look at. I really hope it's something simple.
Dave

I would check the engine tin,like the muffler tin and ISO mounts. Could be a loose muffler clamp too. My 1200 was rattling like crazy had some bolts on the muffler box that worked loose.

I would be concerned about piston slap too. Of course weed out the other things like tin vibrating, etc. too.

Good luck,
Bill

My 108 started making a metallic knocking noise. pulled the head to find a scored cyl, and lots of fine aluminum in the oil. And badly worn piston skirts. It did start to blow smoke out the breather. It wasn't really smoking out the exhaust like it was burning oil at all.

My plan so far is to check all the easy, visible stuff and if I don't find anything there I'll go into the engine. I've got my fingers crossed that the engine is ok

I have a freshly rebuilt 1450 .030 over, new piston & rod that makes the same noise. Really worried me at first and was told they all do it. While the engine was out I did the axle squeeze and ISO mod w/new factory mounts.

My 1250 w/unknown hrs makes the same noises.

Rec'd a lengthy reply from a gentleman in WA state who is a retired machinest.

He stated he had one w/the same problem and set out to find the source.
Seems as though these Kohlers are not all that tight on the tolerances when new. He found that the cam shaft ends and pockets in the block were not true. After lapping the block surfaces, trueing up the cam ends and shimming,
it eliminated the noise and stated he has done at least a dozen engines since and that procedure cleared up the noise in each case.

Dave S.