budman2 57 #1 Posted September 4, 2016 I just bought a 1995 520H Wheel Horse tractor that has about 1100 hours on it, smokes like a freight train! I checked the compression with full throttle and choke wide open, 120psi on both cylinders! Any and all help would be greatly appreciated, Thanks budman2 Share this post Link to post Share on other sites
pfrederi 18,703 #2 Posted September 4, 2016 Diesel Freight trains blow black smoke...Steam freights blow gray/white smoke and sometimes black. What color smoke do you have...makes a difference. Share this post Link to post Share on other sites
budman2 57 #3 Posted September 4, 2016 It looks like a dark gray and smells like oil burning, I have changed the oil twice since I have had it as the prior owner let it get very black! I thought maybe the oil rings where maybe stuck as the tractor has been setting a long time! runs super strong, I don't know what else to check! Thanks for your response, budman2 Share this post Link to post Share on other sites
Elkskin's mower junkyard 1,117 #4 Posted September 4, 2016 what weight oil u put in it and type never run synthetic in a high hour engine thats use to regular oil and alsio if you can make a video Share this post Link to post Share on other sites
budman2 57 #5 Posted September 4, 2016 I use straight 30W Valveline! Share this post Link to post Share on other sites
Elkskin's mower junkyard 1,117 #6 Posted September 4, 2016 Just now, budman2 said: I use straight 30W Valveline! well dark smoke sounds to me like running too rich. i have never seen a oil burner do black smoke heavy unless it was way to rich from gas. usually if its alot of oil being burnt it will appear a white color out muffler then out a couple feet it will have blue tent but i mean alot like scored cylinder bad lol. reason i suggested a video Share this post Link to post Share on other sites
budman2 57 #7 Posted September 4, 2016 OK, thanks! I will post a picture of it tomorrow maybe that will help! budman2 Share this post Link to post Share on other sites
pfrederi 18,703 #8 Posted September 4, 2016 Blue/white oil Black usually fuel. Share this post Link to post Share on other sites
budman2 57 #9 Posted September 4, 2016 Thanks much! I will try and find out tomorrow if it is a rich fuel mixture, I sure hope thats all it is, budman2 Share this post Link to post Share on other sites
cleat 7,263 #10 Posted September 4, 2016 Take off the air filter covers and check that the choke is coming all the way off. The Onan's will run with the choke on due to a spring on the choke butterfly but it will smoke. Share this post Link to post Share on other sites
budman2 57 #11 Posted September 4, 2016 OK, I will do that in a little while! thanks for the input, I have racked my pea brain trying to figure this one out! budman2 Share this post Link to post Share on other sites
rmaynard 16,342 #12 Posted September 4, 2016 @craftsmanmowerfreak I'm curious to know your reasoning for not running synthetic in a high hours engine. I have nearly 1600 hours on my Onan 16 HP and at 1500 hours switched from dino oil to fully synthetic with no issues. No oil burning, no leaking. @budman2 I'd put my money on stuck or worn rings. You can get good compression and still have a bad oil ring. 1 Share this post Link to post Share on other sites
budman2 57 #13 Posted September 4, 2016 OK guys I have tried leaning the carb, made sure the choke is opened, changed to mobel1 full synthetic 10W-30 oil and it is still smoking bad! I suppose the next step is to part it out or sell it as is! I will try and load a couple of pictures of it smoking! picture number three is before I started it! Share this post Link to post Share on other sites
pfrederi 18,703 #14 Posted September 4, 2016 That looks like oil smoke to me. Older tired Kohlers will do that far a minute or so when they first start up but then it seem to clear up. 1 Share this post Link to post Share on other sites
budman2 57 #15 Posted September 5, 2016 Yah I think it is oil burning! Time to part it out, or sell as is, Thanks for all the input guys I do appreciate it, budman2 Share this post Link to post Share on other sites
squonk 43,899 #16 Posted September 5, 2016 Try adding a little Sea Foam to the oil, running it a while and then draining it. You say the old oil was very black.I've had luck with Sea Foam freeing rings and lifters. You could also have clogged oil returns overwhelming the valve guides and seals with too much oil. 1 Share this post Link to post Share on other sites
budman2 57 #17 Posted September 5, 2016 Squonk I tried putting 1/2 can of seafoam in with the oil, let it run about an hour, with no luck! somebody else sugjested changing the oil to synthetic to see if that would clean it up, tried that also, it is still in the motor now, still smoking bad! don't know how long this has been setting in a garage but the oil that came out of it had some lumps in it (no metal though) and very black! thanks for your input, I hate to part it out as it runs good its just a smoken machine, budman2 Share this post Link to post Share on other sites
cleat 7,263 #18 Posted September 5, 2016 Well, you can pull the intake and exhaust then the valve covers to set the valves and verify as Squonk said that the oil drains are open under the tappets. You can also pull the heads for decarboning and check the cylinders for scratches or other damage. Also, you can perform a leak-down test to verify the rings are sealing properly (you may need to find a mechanic that has a tester). This gets a little costly due to the Onan gaskets being expensive but should likely be done anyways if it has not been done in a long time. 2 Share this post Link to post Share on other sites
onanparts.com 185 #19 Posted September 6, 2016 8 hours ago, budman2 said: Squonk I tried putting 1/2 can of seafoam in with the oil, let it run about an hour, with no luck! somebody else sugjested changing the oil to synthetic to see if that would clean it up, tried that also, it is still in the motor now, still smoking bad! don't know how long this has been setting in a garage but the oil that came out of it had some lumps in it (no metal though) and very black! thanks for your input, I hate to part it out as it runs good its just a smoken machine, budman2 Stuck oil control rings most likely. But it's also possible the crankcase breather is stuck open/clogged up. Easy check is looking at the air filter and it's housing to see if oil is present. If dry run engine with air cleaner/filter cover off and see if any blowby is coming out the breather tube. Blowby means stuck oil rings. Under $100 for a set of STD rings, head gaskets and oil pan gasket. No reason to part out a nice tractor due to a stuck oil ring. Might get lucky and it's just the breather that's gunked up. 6 Share this post Link to post Share on other sites
BESTDOGEVER 218 #20 Posted September 13, 2016 Are you getting oil in the air cleaner /intake? My relief valve was stuck and I was getting oil pouring in from the breather made it smoke about like that . Share this post Link to post Share on other sites
budman2 57 #21 Posted September 13, 2016 Yes there is some oil in the breather pan, got tired of messing with it and sold it to one of the members here on red square! I just don't know that much about the onans, but I do hope it is an easy fix for the new owner, Thanks for your input though budman2. Share this post Link to post Share on other sites
Elkskin's mower junkyard 1,117 #22 Posted September 13, 2016 if it was me i would of just repowered it. onans are $$$ to fix. i had one in a sears fuel pump went out and i wasnt paying 120 plus for carb kit so i sold it Share this post Link to post Share on other sites
Uncle Buck 246 #23 Posted September 25, 2016 Really a poor reason to part that machine out if you ask me. Replace the rings and do the valves and seats. That is just too nice of a machine to part out. Share this post Link to post Share on other sites