VIDEO: Kohler K Series rattle.......

[Fordiesel69 271]

Here is a sound I was finally able to record.  During certain parts of the throttle you will hear a rod / piston slap sound / or general rattle.  Hard to explain in words.  A ton of these kohler big blocks do this when there is no load on them.  I also have this engine's points set at .020 and they have been this way since the late 90's.  It I reduce the gap to .018 this knock or rattle will go away.  There is no detonation or preignition.  The engine has never gotten worse, and as I have said, most all the kohlers I have been around have this sound.  When we bought this back in the late 90's, the prior owner had the wheel horse dealer rebuilt it with a .010 piston because of oil buring.  To this day the cross hatch is still there and the piston feels tight.  There is also no rod play that I can feel in the flywheel, but I never measured it.  If it was indeed rod play, by now it would have gotten worse.

 

The valve train clatter you hear is actually not.  The muffler baffle makes this sound, and yes I was fooled as well. 

 

Again, only at certain throttle: K241 10HP on B-100 Tractor

[Fordiesel69 271]

Here is another:

[WH nut 553]

That sounds like a rod starting to rattle to me

[MarkPalmer 81]

It sounds like the noise the rod makes when the crankpin is starting to get out of round. 

 

-Mark-

[Fordiesel69 271]

Interesting.  My new rebuilt engine will do this at .020 and I measured the crankpin and rod.  .002 all the way around.  I measured with platiguage and digital calipers.  I have heard a ton of these with this noise.

[Fordiesel69 271]

In cases where the rattle is present when the rod / crankpin measures good, could slightly worn side bearings be partially to blame? 

 

I read on here that rod clearance greater than .003 is when you will hear it, and at that point the rod will start to wear out quickly.  Is this correct?

[WH nut 553]

I like no more than.0015 clearance

[MarkPalmer 81]

The last one I worked on for a fellow that had the infamous Kohler "rattle" only had it at full throttle while under load.  I didn't find it real loud but it was enough noise to bother him.  When it was taken apart and inspected, most of the crankpin measured only about .001 of wear, except for the point just after TDC where it measured .003 wear.  No appreciable wear was found on the rod bearing.  I think when any part of the crankpin reaches around .003 of wear, the rattle will start to set in and its about time for a .010 under rod and machining of the crank. 

 

-Mark-

[Fordiesel69 271]

Interesting..  Question:  being that so many of them I have heard like this and they have ran for years and years, at what point would you make a determination to rebuild? 

 

The points really are the magic trick.  Take one that rattles and reduce the gap to 017 ~ 018 and it is amazing the difference in sound. 

[520HC 208]

 Kohlers that have this knock for a long time and keep running do indeed have spark knock. I have plowed all day along side JD 140s that you think will blow at any time,and if it was the rod knocking they would. I have tractors in my collection that have had this knock for 15 years, and are still used daily.

[MarkPalmer 81]

Reducing the points gap retards the timing. If the noise is purely from detonation this should be able to eliminate it. If changing the points gap has no effect on the rattle, its something else. The engine can run for a long time with some crankpin wear, some people aren't bothered by the rattle. But in turn I heard plenty of stories of where the engine was, "running just fine then my rod came through the block."

-Mark-

[Fordiesel69 271]

I will be at camp over memorial day and will reduce the gap.  Fingers crossed.

 

Funny thing is my 523 hour Kohler M12 has no noise whatsoever.

[Trouty56 567]

I have a 301, 321, and a 341 K series engines and the 341 sounds just like this.....the other 2 are smooth as glass....gonna follow this thread....

[MarkPalmer 81]

There have been a lot of theories on the Kohler rattle.  I do know that in the one mentioned earlier that I got specifically with this problem, changing the ignition timing would not eliminate the noise.  On that perticular engine, the crank was re-ground and the rod replaced, but I replaced the piston also, (actually bought a piston/rod/ring assembly) it had considerable scuffing on the skirt and wear to the thrust face.  Once rebuilt the noise was gone, but I'm not 100% sure if the noise was coming from the rod/crankpin or the piston.  Before disassembling I used one of those Harbor Freight engine stethoscopes, but couldn't narrow it down with that.  I just chalked it up to there were things measured that were worn out, so I just replaced them. 

 

-Mark-

[Fordiesel69 271]

Well got to run it real hard this weekend, I noticed no power loss by reducing the gap to .017.  The ratlle pretty much went away.  Of course my camera was full of other videos and pics so no new video.

 

I will play with the points on all the future ones I run into and see if it makes a differnce.

 

BTW, how do you adjust timing on the magnum single cylinders?  I have never heard one of those rattle.  But again most are 10-15 yrs newer.....

 

I am wondering if point floating, or plunger slap might possibly contribute to the uneven rattle. 

[MarkPalmer 81]

There is no timing adjustment provision on the breakerless (trigger module) magneto used on the Magnum engines.  The only adjustment they have is the air gap between the flywheel and trigger module, which isn't too critical.  Just about all Magnum engines use the style D Mahle piston with the Posi-Lock rod, two items selected to reduce mechanical noise, reduce heat and associated wear, and reduce oil consumption.  This piston/rod set also showed up an the late production K engines and replacement K series short and mini-blocks, and you can use them as replacements during a rebuild on any K engine provided you use the piston, rings, and rod specific for the Mahle piston, you can't mix and match with the older components.  I really like the Mahle forged piston, it's a mechanical marvel compared to any of Kohler's cast pistons. 

 

-Mark-

[Marv 970]

I have a K321 in my C145 that I Short Blocked with a rebuilt which was done by professional rebuilders who has been rebuilding for 30 years. I hear that noise too. I thought it might be a muffler baffle. Haven't replaced the muffler so do not know for sure. The noise is quite annoying to me because I am thinking the engine might just decide to give up. I certainly don't need that. I had a K341 that had that noise and it did blow. I think it did that (blew) because of the balance gears. My short block does not have balance gears so I know that is not causing the noise.

Marvin

[Fordiesel69 271]

Try the point gap reduction first.

 

In the case of my B100 in the video, I have maintained the oil yearly, but have really "horsed" the engine with the 42" SD deck.  The sounds has not gotten worse.  So I think if yours sounds like mine, it should last a very long time.  If it knocked with a heavy engine load, that is when you will be needing a rebuild.

[MarkPalmer 81]

The engines can last many years with the rattle, and I wouldn't go crazy over it unless it gets real loud.  On the other hand if the engine came right back from a machine shop with mechanical rattles after forking out hundreds of bucks I don't think I would be tolerant of it, because if all the internal parts are in tolerance and clearanced way they are supposed to be, it should run mechanically quiet at any RPM regardless of load. 

 

-Mark-

[Fordiesel69 271]

On a side note, I am finding I need to be very clear of specs upfront when getting machine work done.  Some machinists use car specs from memory instead of using kohler specs.  I always copy the spec pages and inlcude when I drop the engine off.  Otherwise you are getting chevy 350 specs on a K301.  Haha.

[Warning:Unsupervised 82]

Anyone here pull the cover off their engine to see if something is hitting the fly wheel?

 I had one WH I got from a farmer who had it parked inside his barn 2 yrs. I started it up and it blew part of a mouse nest out of the engine cover and one out the muffler too. It sounded almost this bad until I removed the engine cover and dug the rest of the nest out of it. Sounded like a stick in a fan, well' because it was, mice had sticks, nuts, Acorn and Walnut shells, Pay Day candy wrappers and nesting materials jam packed in that engine. It was just amazing how much stuff I pulled out of it.

 Never know' one may get lucky and have something of value hidden inside their Kohler, after all its antique...lol