tntatro 181 #1 Posted July 9, 2022 (edited) I just put a K181 that I rebuilt a while ago on a B-80 and I can't get it to run without knocking. The crankshaft was standard and well within the wear limits, it has a NOS Kohler rod, the bore was standard and well within the wear limits and it has a standard NOS Kohler piston. I'm pretty sure I had all the end plays correct unless I messed up. It also has new main bearings. I tried adjusting the points from everywhere between .016" to .022" and it doesn't seem to reduce it much with a load but it nearly eliminates the knock at low and high idle when set at .019". Setting the points using a continuity tester leaves them at about .022" and it knocks at idle. With points set optimally, even if I have it in low range and go up a slight incline it will rattle as if it has a load. It goes away when on level ground or going downhill. I've rebuilt K181's, K241's and K301's and the only ones I've had this problem with were the K181's. One K181 I did I was able to nearly eliminate the rattle by adjusting the points to .017" and it would only rattle with a decent load such as going up a steep hill in 3rd, I don't remember having much trouble with other K181's I've done. Is what I'm experiencing abnormal and I should definitely take it apart and recheck the specs or are some engines like that? Edited July 9, 2022 by tntatro Share this post Link to post Share on other sites
Snoopy11 5,718 #2 Posted July 9, 2022 (edited) I don't see that you mention anything about valves... that would be the next thing to check... Edit: I'd also take a look at the wrist pin... Don Edited July 9, 2022 by Snoopy11 Share this post Link to post Share on other sites
tntatro 181 #3 Posted July 9, 2022 30 minutes ago, Snoopy11 said: I don't see that you mention anything about valves... that would be the next thing to check... Edit: I'd also take a look at the wrist pin... Don The valves were either new or I had them ground, I don't remember which. I may not have done the best job as far as adjusting the clearances and cutting the seats but I don't think I did a terrible job. I might have adjusted them on the tight side of the specs and I'm sure I lapped them in. If I lapped them after adjusting then that could have made them a little too tight. As far as the wrist pin, that might be a good thing to check also because I can't remember if the piston was an entire kit with pin or not. Unfortunately my Ebay purchases only go back to 2020 and I don't see it. I just remember that it was a good deal for a NOS Kohler part, maybe because it was just the piston? Thanks for the suggestions. 1 Share this post Link to post Share on other sites
oliver2-44 10,708 #4 Posted July 10, 2022 Can you tell if it is detonation knocking verses mechanical knocking? Did you check and shim the clearance on the cam shaft? k181"s usually don't have valve adjusters, you would have ground the end of the valve to set clearance on it. Share this post Link to post Share on other sites
tntatro 181 #5 Posted July 10, 2022 10 minutes ago, oliver2-44 said: Can you tell if it is detonation knocking verses mechanical knocking? Did you check and shim the clearance on the cam shaft? k181"s usually don't have valve adjusters, you would have ground the end of the valve to set clearance on it. I don't know if it's detonation or mechanical knocking but I suspect machanical because I can't get it to stop. When I rebuild them I always follow step bt step by the book so I'm pretty sure I checked clearances. I'm wondering if I just messed up. I ground the valves to adjust them, I might need to take a little more off. Share this post Link to post Share on other sites
tntatro 181 #6 Posted July 10, 2022 I'm taking apart the engine that was originally on the tractor and the piston has some damage but it is still within the wear limits. Does this piston look okay to use? The ring end gaps are outside the wear limits so it needs new rings. The bore looks good except the very top where the piston damage was has carbon that's a little harder to hone out. I'm guessing that area above the top ring area is flared out of the limits a little but the main area of the bore is within wear limits. This engine had good power and didn't knock at all but used oil bad. Share this post Link to post Share on other sites
oliver2-44 10,708 #7 Posted July 10, 2022 I would not reuse that piston with the wear at the top 1 Share this post Link to post Share on other sites
squonk 43,789 #8 Posted July 10, 2022 Piston is junk. What tools are you using to measure the bore ect. Share this post Link to post Share on other sites
tntatro 181 #9 Posted July 10, 2022 14 minutes ago, squonk said: Piston is junk. What tools are you using to measure the bore ect. I have a micrometer set and bore gauge. Looking closer at the bore I see light scoring and I have a new .010" piston so I decided to bore it. I don't have money for a new piston. I'll see what I can do tomorrow. Share this post Link to post Share on other sites
creighton trimble 8 #10 Posted July 13, 2022 What are you running for fuel? I have found the 87 octane in my area to be rubbish and most of my vehicles don't run well on it, this has just been in the last year. Share this post Link to post Share on other sites
tntatro 181 #11 Posted July 14, 2022 28 minutes ago, creighton trimble said: What are you running for fuel? I have found the 87 octane in my area to be rubbish and most of my vehicles don't run well on it, this has just been in the last year. I didn't think of that. I've been running regular 87 octane. I normally use high octane in everything but I don't have much money. I'll have to try some higher octane and see how it runs. Thanks Share this post Link to post Share on other sites
tntatro 181 #12 Posted July 14, 2022 I just tried running 92 octane and it didn't stop the knocking but it seems to run really well otherwise. I guess I'll have to take it apart and re check all the specs. I have the other engine half bored out. My 2 cycle drill malfunctioned just as I was going to re tighten the stones and as I had the hinge bent 90 degrees it let loose and went full throttle on me and cut my finger as it flopped around. Luckily there wasn't any damage to the hone or bore. I just have to let my cut heal a little before I can finish. Share this post Link to post Share on other sites
tntatro 181 #13 Posted July 14, 2022 Here's the drill I'm using. I actually have two, this one isn't the one that malfunctioned. That's a Lisle hone, I also have a Sunnen AN but my stones need to be trued. I started honing with the coarse stone and it was tapering the bore so I switched to the Lisle which has new stones. Share this post Link to post Share on other sites
tntatro 181 #14 Posted July 14, 2022 Here's the B-80 8 speed. I also had to take the transmission apart and replace some bearings. The reduction gear shaft is pitted and the reduction gear bearings were froze up so I put good bearings in it but it still makes a noise when I drive. I got lucky and found a new shaft on Ebay so I'll have to put it in after I get the engine figured out. When I bought it I was hoping to be able to put little time and money into it to make it functional and sell it for a small profit. That didn't happen. Share this post Link to post Share on other sites
Elkskin's mower junkyard 1,117 #15 Posted July 16, 2022 On 7/9/2022 at 5:02 PM, tntatro said: I just put a K181 that I rebuilt a while ago on a B-80 and I can't get it to run without knocking. The crankshaft was standard and well within the wear limits, it has a NOS Kohler rod, the bore was standard and well within the wear limits and it has a standard NOS Kohler piston. I'm pretty sure I had all the end plays correct unless I messed up. It also has new main bearings. I tried adjusting the points from everywhere between .016" to .022" and it doesn't seem to reduce it much with a load but it nearly eliminates the knock at low and high idle when set at .019". Setting the points using a continuity tester leaves them at about .022" and it knocks at idle. With points set optimally, even if I have it in low range and go up a slight incline it will rattle as if it has a load. It goes away when on level ground or going downhill. I've rebuilt K181's, K241's and K301's and the only ones I've had this problem with were the K181's. One K181 I did I was able to nearly eliminate the rattle by adjusting the points to .017" and it would only rattle with a decent load such as going up a steep hill in 3rd, I don't remember having much trouble with other K181's I've done. Is what I'm experiencing abnormal and I should definitely take it apart and recheck the specs or are some engines like that? what headgasket did you use? i have reused k161 headgaskets on k181 and a knock appeared Share this post Link to post Share on other sites
tntatro 181 #16 Posted July 16, 2022 2 hours ago, Elkskin's mower junkyard said: what headgasket did you use? i have reused k161 headgaskets on k181 and a knock appeared I don't remember but it was most likely a new K181 head gasket. After I get the other engine together I might pull this one apart. Share this post Link to post Share on other sites
