tormater 12 #1 Posted March 16, 2017 Hi guys I recently got a 520 at a auction and it seems to burn a lot of oil, when I got it she was only running on one cylinder "the front one" oil was dripping from muffler, the plug in the rear cylinder was gummed up badly, I replaced the plugs now it runs on both cylinders and seems to run well and no oil in the muffler but still burning oil like mad, did a compression test and am getting about 120 psi in front cylinder and about 118 psi in the rear cylinder which makes me think the rings and valves ok? I am about to clean out the breather but seems like it's not plugged or anything??? Share this post Link to post Share on other sites
lynnmor 7,445 #2 Posted March 16, 2017 I have heard of the breather causing problems, aside form being plugged up, check that the parts are in order. Check the valve guides for play and the valve seals, it probably needs de-carboned and valves adjusted anyway. 1 Share this post Link to post Share on other sites
tormater 12 #3 Posted March 16, 2017 OK Lynnmor I'll do thank you Share this post Link to post Share on other sites
tormater 12 #4 Posted March 16, 2017 The breather parts look cleaner than I thought they would! Share this post Link to post Share on other sites
Ed Kennell 39,430 #5 Posted March 16, 2017 Does your vacuum gage work? 1 Share this post Link to post Share on other sites
tormater 12 #6 Posted March 16, 2017 2 hours ago, Ed Kennell said: Does your vacuum gage work? Yes sir it does, I believe this tractor only has 400 and some hours on it, I am amazed the engine does not run like a top, it looks clean too! The tractor even has that plastic thing the small hose connects too on the dash isn't even broke, forget what that is for bit most I see are always broke off 2 hours ago, Ed Kennell said: Does your vacuum gage work? Vacuum Guage really drops when a load gets put on the engine and it puffs it's smoke out then 1 Share this post Link to post Share on other sites
WVHillbilly520H 10,374 #7 Posted March 16, 2017 7 hours ago, lynnmor said: I have heard of the breather causing problems, aside form being plugged up, check that the parts are in order. Check the valve guides for play and the valve seals, it probably needs de-carboned and valves adjusted anyway. I believe @lynnmor was referring to this "breather" or PVC system for the crankcase often overlooked part of maintance it is under the air filter housing and a 3/4" rubber hose is plumbed into the filter base to help pull out crankcase vapors, it has a steel wool like filter and check balls, you have to remove the air cleaner assembly to gain access to it to remove service/clean/or replace, sometimes they get clogged up and won't let the crankcase vent causing high internal pressures which in turn could cause your oil burning issue (picture taken from the owners manual and Onan service manual),Jeff Share this post Link to post Share on other sites
tormater 12 #8 Posted March 16, 2017 16 minutes ago, WVHillbilly520H said: I believe @lynnmor was referring to this "breather" or PVC system for the crankcase often overlooked part of maintance it is under the air filter housing and a 3/4" rubber hose is plumbed into the filter base to help pull out crankcase vapors, it has a steel wool like filter and check balls, you have to remove the air cleaner assembly to gain access to it to remove service/clean/or replace, sometimes they get clogged up and won't let the crankcase vent causing high internal pressures which in turn could cause your oil burning issue (picture taken from the owners manual and Onan service manual),Jeff Yes sir, that's what I took apart and it all looked real clean and seems like it should be working properly, even all 4 check valve balls all were free and looked good, thanks WVhillbilly520h Do see a oily bolt holding the front cylinder head on though, trying to post pics but it always says error. Thanks 1 Share this post Link to post Share on other sites
Ed Kennell 39,430 #9 Posted March 16, 2017 (edited) Sounds like you have a handle on the obvious causes. Does one of the cylinders show a wet plug? Edited March 16, 2017 by Ed Kennell Share this post Link to post Share on other sites
tormater 12 #10 Posted March 17, 2017 1 hour ago, Ed Kennell said: Sounds like you have a handle on the obvious causes. Does one of the cylinders show a wet plug? Yeah Ed the plugs were wet but sparking, I removed the front head and there is oil all over the head oil down in the cylinder, valves were dry but piston very wet Share this post Link to post Share on other sites
Ed Kennell 39,430 #11 Posted March 17, 2017 When you had the head off, did you happen to check the cylinder for damage and size at the bottom of the stroke. I'm thinking damage/ wear at the bottom that could allow oil to be sucked in on the intake stroke and still show good compression as the piston moves up above the damage. Just thinking out loud here and looking for ways for oil to get in the cylinder. 1 Share this post Link to post Share on other sites
tormater 12 #12 Posted March 17, 2017 11 hours ago, Ed Kennell said: When you had the head off, did you happen to check the cylinder for damage and size at the bottom of the stroke. I'm thinking damage/ wear at the bottom that could allow oil to be sucked in on the intake stroke and still show good compression as the piston moves up above the damage. Just thinking out loud here and looking for ways for oil to get in the cylinder. No I haven't yet Ed but I will, the engine was cold when I did the compression test. I am thinking I will be pulling the engine by what I have already seen, I am also thinking that the rear cylinder is probably in worse shape than the front one since that was the cylinder that was fouled when I got the tractor, I have been trying to post pics but it keeps saying that they error has occurred loading the attachment. Thanks Share this post Link to post Share on other sites
Ed Kennell 39,430 #13 Posted March 17, 2017 Becoming a support member will solve the picture posting problem. Go to the STORE for options. Share this post Link to post Share on other sites
tormater 12 #14 Posted March 18, 2017 (edited) On Friday, March 17, 2017 at 8:06 AM, Ed Kennell said: Becoming a support member will solve the picture posting problem. Go to the STORE for options. I supported Ed but still having pic issues, but it probably my phone or something maybe I will get it straigtend out, would like for you guys to see the pics and a leaky oil spot around one of the bolts on the head before I removed the head Pics If I take a screen shot of the photos I guess it works, probably cause my photos go to my SD card maybe,,,, is this gasket blown and could that be the issues? Edited March 18, 2017 by tormater Share this post Link to post Share on other sites
Ed Kennell 39,430 #15 Posted March 18, 2017 Yes, I think the gasket is blown at the oily bolt, but that can't be the reason oil is getting into that cylinder. Share this post Link to post Share on other sites
tormater 12 #16 Posted March 18, 2017 2 minutes ago, Ed Kennell said: Yes, I think the gasket is blown at the oily bolt, but that can't be the reason oil is getting into that cylinder. Wonderful! Hahaha what you thinkin? Rings then with good comp when engine cold? I haven't ran the valves yet but will before assembly. Share this post Link to post Share on other sites
Ed Kennell 39,430 #17 Posted March 18, 2017 Can you mike the cylinder near the bottom? Share this post Link to post Share on other sites
tormater 12 #18 Posted March 18, 2017 (edited) 6 hours ago, Ed Kennell said: Can you mike the cylinder near the bottom? I can when I get home, out of town for the weekend, but do you mean bottom of cylinder meaning closest to the crank or do you mean bottom of the cylinder where the oil is puddles up which would mean a oval shaped bore? Edited March 18, 2017 by tormater 1 Share this post Link to post Share on other sites
Ed Kennell 39,430 #19 Posted March 19, 2017 At the bottom of the stroke( near the crank). And take several measurements to check for oval shape. You should also make the same measurement at the top of the cylinder(near the head), and compare the two. If it is larger near the crank, maybe that is where the oil is getting sucked in. 1 Share this post Link to post Share on other sites
Howie 899 #20 Posted March 19, 2017 If it were me I would be concentrating on the size of the top of the cylinder. About all of the engines I have checked with my bore gage have been bigger at the top of the cylinder. Probably if you take the piston out the scraper portion of the oil ring will be worn off. Will not scrape the oil off the cylinder wall. If dirt enters through the intake and valve area it will wear the cylinder. A lot of these tractors were not serviced like they should have been. Have rebuilt a lot of small engines over the years and one saees a lot of stuff. 2 Share this post Link to post Share on other sites
onanparts.com 181 #21 Posted March 19, 2017 Oil ring stuck, or as already mentioned, worn. 2 Share this post Link to post Share on other sites
tormater 12 #22 Posted March 21, 2017 well looks like the front cylinder measures 3.253 so it is about .003 out of round, will have to pull the engine to check the rear cylinder. 2 Share this post Link to post Share on other sites
HorseFixer 2,013 #23 Posted March 22, 2017 On 3/18/2017 at 9:14 PM, onanparts.com said: Oil ring stuck, or as already mentioned, worn. Gosh this feels like Deja Voo I hafta agree with TJ. on the Oil Ring, I been there done that. Ended up rebuilding mine 100% in 2011. It's really a shame how people neglect these engines. Good luck with it. Share this post Link to post Share on other sites
tormater 12 #24 Posted March 22, 2017 9 hours ago, HorseFixer said: Gosh this feels like Deja Voo I hafta agree with TJ. on the Oil Ring, I been there done that. Ended up rebuilding mine 100% in 2011. It's really a shame how people neglect these engines. Good luck with it. Yup, hopefully I can get by with just new rings, we'll see I guess, anyone have the part # for the rings or a good place to purchase them after I get it apart of coarse? 1 Share this post Link to post Share on other sites
HorseFixer 2,013 #25 Posted March 22, 2017 (edited) Nope because my .20 oversize rings came in a piston kit for $230.00 and all I know is I spent $762.09 all total for the rebuild kit plus machining and incidentals for a total of about $1200.00 back in Nov 2011 Gosh has it been 6 years ago already! Where does the time go? In my opinion it was well worth the $$$ Case That engine on my SNOW CHUCKER will now last me the rest of my life being it only runs in the winter and it is well maintained. Call T.J. at ONANPARTS.COM he will hook you up they have great prices although in 6 years I'm sure prices have naturally went up. ~Duke Edited March 22, 2017 by HorseFixer 1 Share this post Link to post Share on other sites
