M18 Kohler clack sound....

[johnnymag3 2,437]

Looking for the wonderful people here to chime in on this.... I know somebody has crossed this path......

 

 I pulled a running 1000 hour M18 out of one of my herd due to a clicking sound...thought it was valvetrain issues. After pulling the flywheel and seeing no problems, solid charging magnets intact, and no sign of anything rubbing anyplace, I decided to pull off the valve covers. there are no broken springs and the valves are in great condition. When I put the crank bolt back in and used a wrench to rock the rotating assembly back and forth I can hear a click / tap each time I move the mass back and forth an 1/8 of a rotation or so. I am guessing it is a rod tolerance on the crank. Time to strip it and save the parts, or ????

 

Thanks in advance     JOHN    

[johnnymag3 2,437]

Ideas?????

[squonk 38,844]

There is a certain amount of crank endplay. Also a certain amount of crank gear to cam gear backlash. Bot of these will make a little tap sound when you rock the crank. If the noise is that bothersome, pull the head, rotate the piston to TDC and see if you can rock the piston in the bore.

[johnnymag3 2,437]

Thanks MIke…...when the  M18 ran last year there were no noises.... When I started it up this Spring I had the tap / knocking sound....its a bit more thank a tap, it sounds like the thing is going to let loose, but it hasn't, so I decided to look for an explanation...so far I have found none internally or externally. I will yank the heads and see what I find there....Plugs were nice and clean also. No smoke either on this engine. It has led a good clean life, with over the top services and care..

 

thanks again

[johnnymag3 2,437]

I guess nobody wants to take a stab on what is going on, or guess. When I make a full rotation continually it it makes the same click / clack over and over...also it the same spot on the rotation

 

[johnnymag3 2,437]

Bueller?    Bueller?

 

[johnnymag3 2,437]

22 minutes ago, johnnymag3 said:

Bueller?    Bueller?

 

Anybody????

 

[diesel cowboy 263]

I'd lean towards a rod that for some reason started making noise or if it came out of a Horse with the manual pto possibly the bearing on that end of the crank.  Easy enough to pull the cover plate on that end of the engine to check that and if you have a bore camera there is an oil hole there going into the crankcase where you can stick it through and maybe see the rod caps and see if there's any play on them

[Bill D 1,596]

Sounds like valve train noise to me.  How are the valve stem clearances?

[johnnymag3 2,437]

9 hours ago, Bill D said:

Sounds like valve train noise to me.  How are the valve stem clearances?

Tight....maybe  too tight.... Would tightness cause a clack being the gap is not excessive? they are under spec. for gap  All of them.....

[Bill D 1,596]

8 hours ago, johnnymag3 said:

Tight....maybe  too tight.... Would tightness cause a clack being the gap is not excessive? they are under spec. for gap  All of them.....

It might.  I can't say for sure.  Anyone else got any thoughts on this?

[johnnymag3 2,437]

Maybe I need to post this elsewhere so Engine guys get to read this post......

[johnnymag3 2,437]

Looking for the wonderful people here to chime in on this.... I know somebody has crossed this path......This noise was not here last Fall, but starting it up in the Spring ….poof it was there immediately...

 

 I pulled a running 1000 hour M18 out of one of my herd due to a clicking sound...thought it was valvetrain issues. After pulling the flywheel and seeing no problems, solid charging magnets intact, and no sign of anything rubbing anyplace, I decided to pull off the valve covers. there are no broken springs and the valves are in great condition. When I put the crank bolt back in and used a wrench to rock the rotating assembly back and forth I can hear a click / tap each time I move the mass back and forth an 1/8 of a rotation or so. I am guessing it is a rod tolerance on the crank. Time to strip it and save the parts, or ????

 

Thanks in advance     JOHN    

[Handy Don 10,552]

One thing I've noticed on engines that haven't run for a while and get turned manually, is that I can hear/feel the cam making contact with the valve stem to lift start lifting it. I'm assuming its because the oil has dripped off the moving parts.

 

I'd think I might have the head off and put the piston halfway down in the power stroke (i.e. both valves shut so no contact with the cams) and then try gently nudging the flywheel back and forth. Any slack in the rod big enough to click you should also be able to feel. I also might drop the drive belt and confirm that the crank bearings and end play are ok. These would help me dispel any worries or, sigh, realize I had to go deeper.

Good luck!

Edited May 18, 2022 by Handy Don

[953 nut 51,515]

I would doubt the noise is a rod cap since there were no noises prior to being removed.

         If you have an electric motor handy you could crank the engine over and allow the oil pump to lubricate everything and see if it is a matter of dry cam/lifters/valve stems.

[Rob R 951]

My guess would be piston slap...... 

[johnnymag3 2,437]

Piston slap.??   Its way worse than that Rob.....more like a clunk.....Had it running full tilt for 10 min. noise never changed or got worse....

[Rob R 951]

56 minutes ago, johnnymag3 said:

Piston slap.??   Its way worse than that Rob.....more like a clunk.....Had it running full tilt for 10 min. noise never changed or got worse....

Okay Johnny your probably right I had one that was actually blowing smoke rings and it was a combination of rod journals, piston slap (badly worn rings etc.) remarkably the  bore was still with-in max bore spec. and reasonably straight so I carefully honed it out replaced all the aforementioned (3 years ago), cut a 1/3 acre of grass with it yesterday. Runs great no smoke has a bit of a Kohler knock but nothing to write home about..... I'm a happy camper and so is she......  310-8 with a K Magnum 10.

[Snoopy11 5,713]

On 5/19/2022 at 7:13 PM, johnnymag3 said:

more like a clunk.....Had it running full tilt for 10 min. noise never changed or got worse

Has anyone mentioned balance gears...?

 

Don

[953 nut 51,515]

20 minutes ago, Snoopy11 said:

Has anyone mentioned balance gears...?

 

Don

Twins don't have them.

[RED-Z06 2,117]

Flatheads can get carbon on the pistons/heads and theyll make a hellacious knock/rattle. 

[johnnymag3 2,437]

So upon further inspection.....

 

   When I took off the heads, the front piston is not staying square to the bore when i rotate the Crank....It comes up and when it starts to go back down you can see it get tilted about 2 degrees on the one side, the rod is making a noise on the crank when this happens. I can rock the crank back and forth at this position in the down stroke from TDC and it happens every time....Looks like Its done......Rod and or crank issue.

[Handy Don 10,552]

30 minutes ago, johnnymag3 said:

So upon further inspection.....

 

   When I took off the heads, the front piston is not staying square to the bore when i rotate the Crank....It comes up and when it starts to go back down you can see it get tilted about 2 degrees on the one side, the rod is making a noise on the crank when this happens. I can rock the crank back and forth at this position in the down stroke from TDC and it happens every time....Looks like Its done......Rod and or crank issue.

Could be worn piston skirts and rings but .....

[Bill D 1,596]

Loose rod cap?

[Darb1964 1,014]

2 hours ago, johnnymag3 said:

So upon further inspection.....

 

   When I took off the heads, the front piston is not staying square to the bore when i rotate the Crank....It comes up and when it starts to go back down you can see it get tilted about 2 degrees on the one side, the rod is making a noise on the crank when this happens. I can rock the crank back and forth at this position in the down stroke from TDC and it happens every time....Looks like Its done......Rod and or crank issue.

If I recall correctly you have a spare, I remembered admiring it when I was at your place. I was hoping some day I might talk you into selling it. I have the 418-8. With fifteen hundred hours on it, still running strong but it's PO. Was hard on it, makes me a little nervous. Good luck with it!