wrmhaste 235 #1 Posted May 29, 2014 I have a 520h I just picked up. It ran great for a week then I started having trouble starting it. It would start easy when I Pull the air filter off so I bought a new one. No help. I'm getting gas spraying out of the carb. with no filter or cover on the carb it will spray gas out the hood vent. Any info or thoughts would be appreciated Share this post Link to post Share on other sites
Ed Kennell 42,964 #2 Posted May 29, 2014 Sounds like the float is stuck. Time to do some carb cleaning. Share this post Link to post Share on other sites
wrmhaste 235 #3 Posted May 29, 2014 I took the top half of the carb off cleaned everything I could including the needle. And tested to make sure the float floats and it does. I'm going to fully remove it Saturday and do a full tear down and soak it over night. I got such a good deal on it that it's worth throwing money at.... A lot if need be. Share this post Link to post Share on other sites
ericj 1,579 #4 Posted May 30, 2014 is it sputtering and running real bad with a noticeable miss, sound like a valve seat came out do a compression test. does a head look like it might have been off lately, somebody might have done a half repair like peen the seat over and sold it off i would definitely do a compression test before going to much further eric j Share this post Link to post Share on other sites
wrmhaste 235 #5 Posted May 30, 2014 It runs fine. A little under powered. The head nor any other part on it looks like it had been touched in awhile. I trust that the guy I got it from had no idea. He was and older guy mid 60s maybe 70s. His wife bought him a brand new one and made him sell both wheelhorses. I got the 520h and a 310-8 for $150. I plan on doing a compression test Saturday. I may Pull the valve covers and adjust them too. Share this post Link to post Share on other sites
boovuc 1,090 #6 Posted May 30, 2014 That was a great deal regardless of the outcome of the motor issue! Share this post Link to post Share on other sites
seuadr 489 #7 Posted May 30, 2014 That was a great deal regardless of the outcome of the motor issue! no kidding! Share this post Link to post Share on other sites
wrmhaste 235 #8 Posted May 30, 2014 Yea that was my thought. I've been searching for a 310-8 for years but I could never afford one until now. Both have decks that are in great shape. The 520 also came with a 44" snowblower. Share this post Link to post Share on other sites
wrmhaste 235 #9 Posted May 30, 2014 I didn't care if either ran when I made the deal then the guy told me the 520 did. The 310-8 is in decent shape. It needed a good tank cleaning, carb clean, New gas shut of and grommet, it also doesn't start with the key. I think it's a safety because I'm getting power to both small terminals in the crank position. Runs great now though Share this post Link to post Share on other sites
546cowboy 302 #10 Posted May 30, 2014 From my own experience I believe you will find that rear cylinder has no compression. I have had that happen to one. But with what you paid for those two tractors you can afford the repair. You'll love that Onan when she is running right. It should run you less than $200 to put a new seat in there. Just make sure you take it to a good machine shop that has experience with aluminum blocks. Even if the block has been damaged it can be fixed. Been there and done that! Share this post Link to post Share on other sites
wrmhaste 235 #11 Posted May 30, 2014 I'm going to open it up Saturday. I've been researching the issue all week. I have experience with motors big and small and aluminum. I've noticed from looking into these onans that the symptoms they give aren't always the typical symptoms of the problem. Like for instance if the back cylinder isn't working. every other brand I've worked on would barely run and shake boots loose almost. That's why I questioned and feared the worst. It ran prefect 2 weeks ago then started throwing gas so hopefully there isn't too much damage or any. It doesn't shake a bit and both cylinders get hot Share this post Link to post Share on other sites
dennist 139 #12 Posted May 30, 2014 Good luck and sounds like you just got 2 great tractors, best of two worlds a nice cheap running 310 that you have always wanted and then the big Onan. Share this post Link to post Share on other sites
wrmhaste 235 #13 Posted May 30, 2014 Yeah I couldn't believe the price. He started out at 250 for the pair but me being me had to offer lower. Even if the 520 turns out to be a carb issue I'm still going to do the valves and decarbon the heads this weekend. It should be nice and happy after that. The muffler is kinda beat too. after seeing the price of them I'm going to make my own. I have access to a full machine/fabrication shop and plan on making a full stainless one to factory specs. Any thoughts? Share this post Link to post Share on other sites
ericj 1,579 #14 Posted May 31, 2014 were you wearing a mask when you got both tractors for $ 150.00, even at $ 150.00 each that's a real good deal. if both cylinders are getting hot it could still be a valve seat do a compression test and it will tell you how far you have to tear down, good luck and how about some pictures eric j Share this post Link to post Share on other sites
wrmhaste 235 #15 Posted May 31, 2014 I'm not quite sure how to add pics. I have a couple of the 520 Share this post Link to post Share on other sites
Red-Bovine 337 #16 Posted May 31, 2014 My guess is a valve seat is loose. Comp test will confirm that.I had three of them go on three separate occassions. Worth repairing for that price. Red Share this post Link to post Share on other sites
wrmhaste 235 #17 Posted May 31, 2014 Yea that's my first step today. I'm itching to work on it now but I have to wait until my wife gets out of work. My 6 month old daughter is a little young to help me pull a motor just yet. Share this post Link to post Share on other sites
wrmhaste 235 #18 Posted May 31, 2014 Ok so I kinda jumped the gun. My mother in law offered to watch the baby for a bit. The back cylinder has half compression. I pulled the valve covers. Everything looks good except the intake valve on the back cylinder is not closing all the way. There is almost no clearance. But there is one point where there's just enough clearance to spin the adjustment. I'm thinking that was causing my gas blowing out the carb.? I'm going to try pulling the heads cleaning everything and adjusting the valve clearance. hopefully that is all it needs. My yard looks like a hay field. I don't think the valves have ever been adjusted. It has 882 hours Share this post Link to post Share on other sites
dennist 139 #19 Posted May 31, 2014 Yeah I couldn't believe the price. He started out at 250 for the pair but me being me had to offer lower. Even if the 520 turns out to be a carb issue I'm still going to do the valves and decarbon the heads this weekend. It should be nice and happy after that. The muffler is kinda beat too. after seeing the price of them I'm going to make my own. I have access to a full machine/fabrication shop and plan on making a full stainless one to factory specs. Any thoughts?Stainless muffler.... I am sure there are others, but look through this build. A couple pics of it now.... Share this post Link to post Share on other sites
wrightorchid 261 #20 Posted September 1, 2014 anybody making stainless for a magnum 12 (on a 312-8)? Share this post Link to post Share on other sites
cheesegrader 434 #21 Posted September 1, 2014 Man, I would love a stainless replacemet muffler. I think I bid on the one that dennist has, but he took it! If it still in the box, and not on the tractor, it would be really easy to send it to me! Share this post Link to post Share on other sites
