wooley12 0 #1 Posted June 21, 2011 Before I invest in a rebuild I need to know why it broke. C-120 with a Kohler 301S. Had it for 20+ years. Rebuilt with a +.20 piston about 400 hours ago. Last week the rod broke. No case damage. Some minor scouring in the bore. Seized wrist pin and aluminum bonded to the crank. No weird sounds leading up to the failure. I was using 10w-30 or whatever went into my cars winter and summer as I have for 20 years. Would that do it? Share this post Link to post Share on other sites
rmaynard 14,888 #2 Posted June 21, 2011 Lots of questions to be answered. Did you do the rebuild? Did you use Kohler or aftermarket parts? Did you do a lot of mowing on slopes? Was the rod installed correctly (hole toward camshaft)? That probably would have caused failure very early. 400 hours? How many years does that amount to? How many oil changes in that time? Kohler does call for 30W except in colder weather. The oil should be NON detergent. The oil for newer cars is detergent. The difference is that car engines have filters. Detergent oil has additives that allow the dirt and sludge to mix with the oil, then it is filtered out at the oil filter. Non-detergent oil allows the dirt to sink to the bottom of the oil pan since there is no filter on the Kohler engine. edit: :hide: Share this post Link to post Share on other sites
wooley12 0 #3 Posted June 21, 2011 Thanks for your reply. "Lots of questions to be answered." - Good, a knowledgeable answer always begs more questions "Did you do the rebuild?" - No. rebuilt be a guy who rebuilds engines for the surrounding towns Maint. Depts. Knows his stuff. "Did you use Kohler or aftermarket parts? "- I'll assume yes. Are OEM parts marked as such? "Did you do a lot of mowing on slopes?" No but I see where you're coming from. "Was the rod installed correctly (hole toward camshaft)?" Lets assume so. Didn't check that when I dropped the pan and removed the pieces. "400 hours? How many years does that amount to?" - Hours are an estimate. Rebuilt in 2005 "How many oil changes in that time?" Every 50 hours or so. Beginning, middle and end of each season. Never let it run low. Share this post Link to post Share on other sites
Jim_M 178 #4 Posted June 21, 2011 Aluminum welded to the crankshaft suggests lack of lubrication. Either too low on oil or too light weight, but normally any oil at all will keep the rod from welding to the crank. Share this post Link to post Share on other sites
wallfish 15,918 #5 Posted June 21, 2011 :hide: Has the carb flooded recently? Reason I ask is because it could be possible that fuel entered the crankcase and mixed with the oil. Share this post Link to post Share on other sites
W9JAB 156 #6 Posted June 21, 2011 :hide: OIL,OIL,OIL. :WRS: Share this post Link to post Share on other sites
wooley12 0 #7 Posted June 21, 2011 OIL,OIL,OIL. Nope-- Edit - Oops. quoted the wrong reply. Gas in the oil was not it. Your right I'm thinking. Lack of lube and probably operator error of some kind. Share this post Link to post Share on other sites
Raider12 13 #8 Posted June 21, 2011 The 10w20 would do it. I made the same mistake once. Share this post Link to post Share on other sites
W9JAB 156 #9 Posted June 21, 2011 I worked repairing commercial pressure washers for 14 years, 99.9% of small engine failures were oil related. :hide: Share this post Link to post Share on other sites
VinsRJ 721 #10 Posted June 21, 2011 How deep are the scores in the bore? And what condition is the crank in? You might need to locate another engine all together. Share this post Link to post Share on other sites
JC 1965 1,528 #11 Posted June 21, 2011 :WRS: Hello and :hide: Share this post Link to post Share on other sites
mavfreak 11 #12 Posted June 21, 2011 :hide: I would have to say oil. I do think that WH recomends 10w30. But I just feel that the 10 is to thin at start up and it does take time it get up to the 30 JMO. Share this post Link to post Share on other sites
tunahead72 2,337 #13 Posted June 22, 2011 The oil should be NON detergent. The oil for newer cars is detergent. The difference is that car engines have filters. Detergent oil has additives that allow the dirt and sludge to mix with the oil, then it is filtered out at the oil filter. Non-detergent oil allows the dirt to sink to the bottom of the oil pan since there is no filter on the Kohler engine. Seriously? Bob, I've read lots of your posts since I first joined this group back in March, and you seem to know your stuff, so I respect your opinion on this topic. But I've never heard anybody recommend using non-detergent oil in these machines, or maybe I just wasn't paying attention at the time. On the other hand, I'm certainly no expert, and my 310-8 engine has been rebuilt twice since I bought it new in 1987. Just curious, is this common knowledge, or are there other opinions? Share this post Link to post Share on other sites
Save Old Iron 1,563 #14 Posted June 22, 2011 the operators manual these folks usually know somethin' Share this post Link to post Share on other sites
Save Old Iron 1,563 #15 Posted June 22, 2011 Opinions that are simply cut and pasted from tractor puller sites may not be the best advise especially if they disagree with manufacture's recommendations - see post above. Take this opportunity to learn a little more about the hobby. There can be many things learned from post mortem parts inspection. Witness marks (wear marks) on the rod and rod cap (and piston skirt) can be helpful in putting a story behind the root cause of the destruction. Also, Please help me understand this whole detergent / non detergent issue. How do the "settled out" contaminates in non detergent oil get to just sit harmlessly at the bottom of the oil pan when the oil dipper is thrashing thru the oil pan mixing it all up. :hide: Share this post Link to post Share on other sites
sorekiwi 761 #16 Posted June 22, 2011 I've heard the non-detergent argument a few times over the years, and I think it could have some merit, but the bottom line (for me at least) is that Kohler states to use detergent oil, and I figure that no-one knows more about Kohler rngines than Kohler themselves. I'm also a fan of the straight 30 wt oil, as soon as the temps get warm enough to run it. I have several Kohlers that are getting a little long in the tooth, and while they will burn a negligable amount of 30 wt, they will burn a noticeable amount of mukti-grade oil. Somewhere on the Kohler site is a manual tthat goes with their "Online study course". Within its pages there are a lot of clear color photographs of different types of engine failures, as well as text describing failure analysis. Well worth a download, I dont have time to find a link for it right now. Share this post Link to post Share on other sites
rmaynard 14,888 #17 Posted June 22, 2011 Bob, I've read lots of your posts since I first joined this group back in March, and you seem to know your stuff, so I respect your opinion on this topic. But I've never heard anybody recommend using non-detergent oil in these machines, or maybe I just wasn't paying attention at the time. I should have said that the information that I posted was straight from the guru of all Kohler engine guru's Brian Miller. We all quote him from time to time, and for a shop that has rebuilt more Kohler engines than anyone else I know, I kind of take his word as gospel. Here is the link to the section of his Kohler engine website that states what I printed: http://gardentractorpullingtips.com/engine.htm#oil Share this post Link to post Share on other sites
rmaynard 14,888 #18 Posted June 22, 2011 Please help me understand this whole detergent / non detergent issue. How Share this post Link to post Share on other sites
VinsRJ 721 #19 Posted June 22, 2011 At the end of the day Kohler recommends straight 30W..... thats what you should use, IMO. Plus if the rod welded its seft to the crank then there was a real lubrication issue. Any pics of the crank and bore? We can go round and round on personal feeling on oil but what is the outlook for your motor? Share this post Link to post Share on other sites
wooley12 0 #20 Posted June 22, 2011 I started this thread knowing that the reason for the failure was a lack of lubrication. The questions was "Why?". I've been around small engines since, as a teenager, I used a hacksaw, rat tail file and sand paper to hop up a 2-stroke motor and go motorcycle racing. I've had pistons seize and wrist pin bearings go and the oil in a Chevy V-6 turn to pudding so I have some experience with engine failure. The hope here was to find a cause that would vindicate me as the guilty party. I've looked at the failure manual previously posted and will post pictures to enable the community to reach a verdict. PS- I'm active on other forums (mostly ski forums) as Wooley12 so a google search may give you some background. Share this post Link to post Share on other sites
rmaynard 14,888 #21 Posted June 22, 2011 Sometimes the answers can't be 100% known. Without taking broken parts to a metallurgist to do an "autopsy" to see if it was metal fatigue in the rod, or a manufacturing defect, you will never know for sure. The only thing that you can do is look at all possible causes and draw your own conclusion. My money is on lack of proper lubrication. I know there is a bit of controversy on detergent vs. non-detergent, but multiple oil changes during each season can nullify any difference. One thing that surprised me when I first read the Kohler manual is that idle speed should be between 1100 and 1200 RPM. Below that speed causes lack of lubrication due to the fact that the slinger cannot get oil to the top of the engine. Do you know what your idle speed was set to? Share this post Link to post Share on other sites
W9JAB 156 #22 Posted June 22, 2011 You mentioned idle speed, this brings up a good point. This type of motor is made to run at full throttle, it needs the speed to keep the oil splash working as well as the cooling fan. If you Share this post Link to post Share on other sites
daemon2525 5 #23 Posted June 22, 2011 You mentioned idle speed, this brings up a good point. This type of motor is made to run at full throttle, it needs the speed to keep the oil splash working as well as the cooling fan. If you Share this post Link to post Share on other sites
squonk 38,902 #24 Posted June 22, 2011 Not saying any one's right or any ones wrong but in the oil debate My 90 210-H was purchased new. It has over 750 hrs. on the 10 HP vertical Briggs. I have mowed ,plowed snow,blown snow and pulled down small trees. The motor has NEVER been touched except for oil changes in spring and fall, air filters and spark plugs. All on Napa 30 Wt detergent oil. Share this post Link to post Share on other sites
VinsRJ 721 #25 Posted June 23, 2011 I have no problem throttling up and pulling a wheelie or two :hide: Share this post Link to post Share on other sites
