Docwheelhorse 2,560 #1 Posted January 8, 2010 Hello All and Happy Late New Year--- My C125 has developed a knock that seems to be slowly progressing to doom the more I use it---yah I know quit while I'm ahead and I plan to. My question is--I run Mobil 1 15/50 synthetic and have run it for the 15 years I have owned this tractor. The motor sounds absolutely PERFECT when its cold.... no knocks, ticks, rattles or ANYTHING. ---BUT--- as it heats up it starts rattling as I let out the clutch and the motor gets a load on it. It rattles mildly just sitting there running after its hot too. Is it that the cold oil is keeping things quiet until it warms up or do I have a problem other than the rod loosening up--- I.E. balance gear syndrome? I hate to tear the motor down... it uses NO oil and the oil comes out as clean as it went it when I change it a couple times a year. I guess its just bad luck.... Tony Share this post Link to post Share on other sites
rickv1957 70 #2 Posted January 9, 2010 Ive had several kohlers that ran great but had a piston rattle from wear,maybe your problem? Rick Share this post Link to post Share on other sites
rocking 416 1 #3 Posted January 9, 2010 This may sound " Primative " but it does work. This is how i isolate knocks. Run the engine. Take a good screw driver pry bar somthing metal put one tip to the engine block other to your ear. Or you can go to harbour freight there mechanicscopes are pretty cheap :thumbs: Share this post Link to post Share on other sites
Kelly 1,028 #4 Posted January 9, 2010 Before you tear to deep, try adjusting the valves, only takes about 20 min. you have to pull the carb, and the breather assembly, but I've fixed a few knocking engines that way not saying it's not a rod or piston, I'm not there, but it's worth a try only cost a few gaskets, and time, and you could reuse the old gaskets just to see if it fixed it. Share this post Link to post Share on other sites
big mike 13 #5 Posted January 9, 2010 I would try changing the point gap both ways thereby changing the timing and see if that helps.Next I would check for grenade gears and if they are there take them out and while you have the pan off check the cam end play.All those can make sounds that can seem like a rod knock. Share this post Link to post Share on other sites
418a 0 #6 Posted January 9, 2010 Doc with the knock,Check the point gap,Thats where I would start.Brian Share this post Link to post Share on other sites
clintonnut 126 #7 Posted January 10, 2010 The K321 I just pulled apart for my puller sounded like it had a knock but the piston wrist pin was stuck in the connecting rod and the piston was rocking in the cylinder. The crank journal and rod bearing were fine. Charlie Share this post Link to post Share on other sites
mrocket49 23 #8 Posted January 10, 2010 I would try changing the point gap both ways thereby changing the timing and see if that helps. +1 When my C-125 was knocking, the Wheel Horse mechanic told me to set the point gap at .017 instead of .020. It has the effect of retarding the timing and the knocking stopped. Not saying that will cure your problem but it's free to try. Share this post Link to post Share on other sites
420lse 18 #9 Posted January 10, 2010 Hey Tony I would try mrocket's. Just cuz it's the least expensive cure If that dosen't work, often the head will carbon up and it sounds like the rod or wristpin bearings are worn and slapping. After 15 years of service and good old fashioned maint.Not to mention the use of superior oil and I'll bet she gets regular changes, I can't imagine that it's a bearing. Hopefully I'm right. Share this post Link to post Share on other sites
Cody 269 #10 Posted January 10, 2010 I would change the oil and put in Lucas synthetic 10-30, I used it in my C-141 and the noise it had devolped went away, it stopped my 417 from smoking a little on start up. It usually solves engine noise and smoke. Amazing what that stuff will do. Maybe worth a shot. Share this post Link to post Share on other sites
jusjeepn 59 #11 Posted January 10, 2010 Remember, "Mechanic in a can" has not been invented yet! :thumbs: Share this post Link to post Share on other sites
Docwheelhorse 2,560 #12 Posted January 11, 2010 Thanks for all the ideas.... I think I will start with the points Seeing as they where the set that was in it when I got it and I have sand-papered and re-gapped them several times after they oxidized in storage. Maybe its time Cheapy McCheap Pants buys a new set.... Tony Share this post Link to post Share on other sites