High Pitch Rattle on a K321

[Ambush]

Ok, pulled the motor and took the pan off and pleasantly surprised at how clean everything is. I'm pretty sure the noise is the counterbalance gear. It's very loose on it's stub shaft and flops around excessively.

Now I've heard of leaving the gear out altogether. What would the experienced advise?

Looks like I'll need to bore over and a valve job.

[Billy-O]

Originally Posted by Ambush

I'm pretty sure the noise is the counterbalance gear. It's very loose on it's stub shaft and flops around excessively.

Now I've heard of leaving the gear out altogether. What would the experienced advise?

Use green loctite ......No.....Seriously, remove the counterbalance gears.

[Cubcadet_107]

There should actually be 2 gears, an upper one and a lower one. Remove them both, if you don't then there's a good chance that one (or both) will decide that they no longer wish to live inside the engine, and carve themselves an escape route .

The lower gear is easy to remove, but to get the upper one you either have to pull the crankshaft or use a rod and hammer to "destruct" the gear. I ended up "destructing" the top gear on mine as I did not wish to pull the crank.

[Ambush]

Yes, two gears. I'm sure the top one is just as bad as the bottom. Flopping around like two seagulls fighting over a mackerel. The block is getting stripped out for boring and valves.

Billy-O, real Loctite is very expensive! There must be a cheap e-bay alternative

Not often the recommended repair saves both time and money!

[Ambush]

Case is stripped out except for the cam shaft and valves. I had to scab together a puller for the basket pulley. Hopefully never need it again. I may put on a plain pulley and keep the original with the PTO incase someone wants to add one to their motor.

The crank measures .001" under 1.500" and half a thou out of round. It and the con rod look good. Cam lobes look good.

Lots of spalling on the balance gear stub shafts and I'm pretty confident that's where the noise came from. Getting ready to crater and just singing about it. Crank bearings look and feel good. Probably change them just because.

Jug is still standard bore. Though no scoring, it needs to go oversize.

Now I have to clean this mess up.

[twoton]

Good thing you caught that!

[Ambush]

^^^ Yes, I don't need to be the guy that shares pics of his grenad'ed Kohler.

This engine was a smoker and I figured it would be valves and piston rings. Checking them, I'm pretty sure the valves and guides have been replaced and the seats machined.

But the rings! The piston has a lot of wash on the top lip in one spot, and a little scuffing on the shirt. Bore has normal wear. The ring gap, in the top, is .120"
Yup, one hundred twenty thousands. And of course much more in the wear area of the stroke.

The con rod had crude match marks on it, so the piston has been out. I'm wondering if someone just stuck a set of real cheap rings in it without deglazing?

[Cubcadet_107]

IMO piston rings worn that much is actually a sign of overheating. Get some crud up against some of the cooling fins and that section won't cool. Thus the rings begin to heat excessively, wearing out parts of them rapidly while other spots don't wear.

Either way definitely good that you've torn it apart, probably wouldn't last too long with rings that worn.

[Ambush]

The gift that keeps on giving! Cleaning up the oil pan and what do I find? Yup, somebody inflicted a blow to the drain plug, denting the pan and cracked on the inside from the bulging. Also a hairline crack running right through the threads. Well crap!!

I don't have a tig welder at home and the one in my old shop has been stored away since I retired. Wire feed is not the best for this, and oil saturated aluminum is a total pain at best. But I cleaned as much as I could, sweated out as much oil as would come out. The normal course for this is to cut into it then run a hot weld over it, which will be full of holes. Then with a very coarse burr, cut it out and repeat till its good. Couldn't find a suitable burr. The inside cracking was full of oil. I ended up welding over the outside. It's sure not pretty, but I got it and even sealed the plug face.

There is some damage to the engine mount bolts holes from bolts being loose and rattling around and I don't think there's enough meat to heil-coil them. I'm going to make studs from grade eight threaded rod, run them in full length with gap filler Loctite. And leave enough length through the cradle for a hardened washer and a ny-lock nut.

[finsruskw]

Probably lifted it with a floor jack on that area.
Ditch that pan and find a cast iron piece.