kthack657 254 #1 Posted February 12, 2017 Hello all, I have a custom tractor with a 16 hp onan, it worked ok when I got it, but when I was putting it away for the winter, it started having issues and would not run, started backfiring and spewing fuel out of the carb. Welll I took it out of winter storage and charhed the battery up, and again trued to start it...no luck... JimT1971 thought perhaps the carb and intake needed to be cleaned, so we cleaned it all up yesterday and put it back together, this time we were able to get it to run briefly, but it still spots fuel and when the air cleaner is on it you can hear it backfiring from that area...JimT1971 believes that perhaps the valves need to be adjusted, but well Onans are definately not my strong point and I need a lot of guidance from the experts. Thank you in advance Share this post Link to post Share on other sites
lynnmor 6,762 #2 Posted February 12, 2017 Periodic valve adjustments are a normal maintenance procedure. My guess is that the carb and intake still needs closer attention. It is easy to miss an air leak, float leaks or dirt in carb passages. Share this post Link to post Share on other sites
kthack657 254 #3 Posted February 13, 2017 I dont think it is the carb and intake, we cleaned up a spare, and put everything back together, and it is still doing the same thing...I believe it has to be the valves just from the amount of fuel that us getting pushed up through the carb... Share this post Link to post Share on other sites
ericj 1,576 #4 Posted February 15, 2017 sounds like the valve seat came out. My first 520 had a valve seat out and I could only get it to run with the air cleaner off. do a compression check to see which if a cylinder is down. onan says that you should have at least 85 psi per cylinder. good luck eric j Share this post Link to post Share on other sites
kthack657 254 #5 Posted February 18, 2017 Thank Eric, I will have to pick up a compression gauge, I am hoping that is not the case, it was put away and had no issues, but wouldnt start when we went to move it, that us when it started having the issues...do you have any recommendations for shops if it is the seat, or would it be better to look for a replacement Share this post Link to post Share on other sites
kthack657 254 #6 Posted February 19, 2017 Well did the compression test...no compression in the back cylinder and 90 psi in the front so now the motor is coming off I hope it is just a stuck valve and not a seat, but already have help if it is, wish me luck 1 Share this post Link to post Share on other sites
kthack657 254 #7 Posted February 19, 2017 IT is NOT the valve seat waaahhhhooooooooooo, we pulled a screw out of the valve... I have no clue where it came from or how it got there but am sooo happy I could cry right now I have a picture but it wont let me upload at the moment 2 Share this post Link to post Share on other sites
oldredrider 2,547 #8 Posted February 19, 2017 Check your carburetor for a missing screw. Throttle and choke plates especially. Share this post Link to post Share on other sites
kthack657 254 #9 Posted February 19, 2017 We did that already, this screw does not go to anywhere on the engine, it had to be a mishap when the engine was redone last year, before I got it... Share this post Link to post Share on other sites
cleat 4,936 #10 Posted February 19, 2017 There are also 3 little screws that hold the air cleaner onto the carb. I am always afraid of dropping one of those. Keeping the choke on helps. Cleat 1 Share this post Link to post Share on other sites
kthack657 254 #11 Posted February 19, 2017 This screw was bigger than those holes, we believe this was a screw from something else entirely, we were just lucky that there was no damage to anything Share this post Link to post Share on other sites
ericj 1,576 #12 Posted February 20, 2017 karen and jim; glad it worked out for you and turned out to be nothing major, just when you think that it is as bad as it can get every now and then it does turn around, good luck eric j 1 Share this post Link to post Share on other sites
kthack657 254 #13 Posted February 26, 2017 It lives!!!!! Oh man I cannot believe it is alive!! 20170225_161650.mp4 Share this post Link to post Share on other sites
onanparts.com 178 #14 Posted March 2, 2017 On 2/25/2017 at 4:10 PM, kthack657 said: It lives!!!!! Oh man I cannot believe it is alive!! 20170225_161650.mp4 You got screwed! Nice to see you also got unscrewed! The Onan sure sounds sweet with that custom exhaust! 1 Share this post Link to post Share on other sites
WHX?? 46,707 #15 Posted March 2, 2017 (edited) Was that the raffle tractor at last years BS Karen? Say hey to Jim for me! Edited March 2, 2017 by WHX9 Share this post Link to post Share on other sites
kthack657 254 #16 Posted March 4, 2017 (edited) Yes it is in fact the raffle tractor, now that the engine runs,it got some new front tires, I am working on a different seat pan and will be finishing what Eldon, the Hornings, and Ken started. I just need a few more 70 degree days this winter/spring... Edited March 4, 2017 by kthack657 Share this post Link to post Share on other sites
wildman 205 #17 Posted March 4, 2017 On 2/19/2017 at 1:46 PM, kthack657 said: IT is NOT the valve seat waaahhhhooooooooooo, we pulled a screw out of the valve... I have no clue where it came from or how it got there but am sooo happy I could cry right now I have a picture but it wont let me upload at the moment I would adjust valves at this time 1 Share this post Link to post Share on other sites
