What exactly is the "Kohler rattle"?
 

So this 102 I got recently, I had to do some TLC to get it going again but the engine has a rattle sound when it's running. I asked the seller about it and he said all the IH cubs he's had do that, they call it the "Kohler rattle".

I was doing some googling and it could be a number of things. But most people say they've had K-series run for 20 years with the rattle. Some people said even freshly rebuilt engines have the rattle. Is this normal?

The front PTO clutch is not installed, could that cause an issue with the balancing? I just don't want to be going one day and sling a rod or something...

Congrats on the "102"! The common clunky rattle on the old Cubs is from the sloppy, possibly worn out drive clutch mechanism. I'm sure the "anti rattle springs" are missing in action and the clutch disc holes are a little oversized. Other causes include; PTO clutch knocking around in the pulley basket...you said the PTO clutch was removed. You could have a rod knock, cam gear gear/shaft with too much end play. It is an old tractor that may have issues that are not impossible to correct.

This is the first time I'm hearing of the "Kohler Rattle"

Guess the first thing you need to figure out is if it is the engine, the clutch, or the transmission.

You state that the front PTO is not installed, so that's ruled out.
Having it off is not going to effect the balance.

It's possible it could be the drive clutch, I haven't yet took it for a drive yet since I need to change the oil. The carb was leaking bad so there is gas in the oil. Could that cause the rattle? I know low oil pressure can cause a knocking sound...

Non pressurized oil system....good ol splash loob ree kated. ( ol' George speak)

I'm hoping an oil change is all it needs! I got a fresh jug of SAE-30, per the manual lol

Oil changes are always recommended. It may be an old machine, but with proper repairs and maintenance it will be a fine little tractor. :beerchug:

If you have fuel in your oil, you're not going to have sufficient lubrication, which will cause a variety of noises.

Perform an oil change and see if it sounds better.

Oil change completed but the rattle is still there. And she smokes a bit, mostly when throttling up. This engine has likely never been rebuilt I suspect, so it's 60 years old all original...

set the timing with a timing light . s mark on flywheel mark it with paint or something visible adjust point gap to correct timing . clean or replace points first

I have seen that online where people say adjusting the timing to 18 instead of 20 fixes it the rattle. I'll look into it

Check for loose grass screen on the flywheel....

Snake oil I say!:bigthink:

My 149 makes so many friggin' noises that I gave up worryn' about them.
But that was 15 years ago. Still starts & runs fine, and does the job.
Sometimes searchin' for the devil brings more agony than bliss. :bigthink:

I checked the point gap and it was correct at .020 but the contacts were severely worn and concave. I replaced the points and condenser since the seller provided a new set. Engine still sounds the same. It's somewhere between a knock and a rattle, almost like something inside is loose/wobbling. She definitely needs a rebuild as I suspect this is all original from 1966.

Side note, now the carb is leaking. I replaced the bowl gasket and it was fine for a while, now it's leaking out the throat which means the float is stuck. Gimme a break...

So clean the crud from under the needle seat and it will stop leaking.:biggrin2:

Improper cam shims, to loose.
Spec is .005"-.010" for 240,301, 321 & 341

If you've ever been around an old Harley you would've heard the same noise. Solid valve lifters are a major contributor to the "KOHLER RATTLE". More noticable at idle/low rpm.

It does seem to smooth out at higher RPM :bigthink: