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69-Raider-10

Onan 16 (516-H) Fuel in the crankcase

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Good morning gents. Picked up a 516-H the other day and finally got to tinkering with it. Keep in mind it was a sub $400 purchase so the plow and the fact that it runs at all is a good thing. Now when the air filter cover came off it was dripping with a mixture of gas and oil. Seems like it was blowing out of the breather maybe? Then after the old oil was drained (or should I say the 30:1), new oil was added and it was run for a few minutes. Oil was drained and it reeked of gas. Any suggestions on how to tighten this up? Motor need a valve job and rings? As always, your input is valued and appreciated! Here's some pics of exterior motor. 

Thanks again!

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Posted (edited)

Not sure, but can a leaking pulse fuel pump pull fuel into the crankcase ??

Edited by Ed Kennell
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32 minutes ago, Ed Kennell said:

Not sure, but can a leaking pulse fuel pump pull fuel into the crankcase ??

Interesting you say that Ed. That's exactly what the fella thought it was that I got it from. I put no stock in it at the time considering he muffed up a perfectly good plow by welding brackets on it because he couldn't figure out how to mount it. :lol: 

So, clean the carb and get a new pulse pump? Can I rebuild it?

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:twocents-02cents:              I would replace it with an electric low pressure fuel pump.

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1 hour ago, 69-Raider-10 said:

 

So, clean the carb and get a new pulse pump? Can I rebuild it?

Can't rebuild the Onan fuel pumps and the factory O.E. is near $100 but there is good news I get them off :techie-ebay:a 2 pack for $20 and so far so good,  you can disassemble the old pump and check the flimsy diaphragm for holes (usually caused by ethanol/dirt in the fuel) and a weak plunger spring but again it's not rebuildable unless someone starts making kits, Jeff.

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:text-yeahthat:or I'll second Dick's fuel pump suggestion. Don't forget a fresh fuel filter and lines as required. Give her a good bath and check/clean the breather per manual. Make sure those fins are clean.  Looks like ya got a new air filter already. Check spark plugs for correctness.

Do a compression check or better yet a leak down test for those valves/rings suspicions. A valve adjustment might be in order too. Might want to take a peek at the fuse block and 9 pin for issues.

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Posted (edited)

check the bolts on the bearing cover plate, lots of oil around that part of the motor. if the carb is leaking fuel through would be or should be blowing a lot of black smoke and the float should be heavy or the needle seat has dirt blocking it open but that should cause it to burn rich again blowing black smoke. make sure the block off plug is in place for the oil filter hole, it will help keep the motor cool. good luck

 

 

 

 

 

eric j

Edited by ericj
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On 8/31/2017 at 7:01 AM, Ed Kennell said:

Not sure, but can a leaking pulse fuel pump pull fuel into the crankcase ??

 

I pulled the back plate off my pulse pump and inspected the diaphragm for leaks. I didn't want to just buy one if mine was good. Mine was like new.

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In your first picture, what is the tan round disk with three nuts? Can you post a picture looking into carb with choke off?

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the early onan ran that plate that covered the carb it was a round plastic disk with legs that helped keep the air cleaner base bolted down. I have removed or not reinstalled them on some motors if they were missing to start. the later onan's didn't have them. not sure what year they quit using them

1 hour ago, 1995 520H+96+97 said:

In your first picture, what is the tan round disk with three nuts? Can you post a picture looking into carb with choke off?

 

 

 

 

eric j

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Sorry for the late response fellas. Can't thank you enough for all the awesome input. Haven't had time to run through everyone's advice and formulate a game plan. So far from what I read I'll be buying an electric low presure fuel pump and a two pack from Ebs. Can't hurt to have backups! From that point it looks like testing to further diagnose the problem assuming the pump doesn't fix it. I will also put up another pic if ericj's response didn't already clear up your question 1995? I promise I will post an update and more pics. Been so busy lately working on a Bolens 1254 I picked up, as well as a Grasshopper 721 Zero Turn. I'll tell ya, I'm liking this TRA-12 Wisconsin! Strong motor! Thanks again all! Updates coming!

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Well this could have something to do with the sluggish feeling and lack of raw power, a dead piston with a snapped connecting rod. :mellow:

To rebuild or to repower! THAT is the question! :lol:

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In the meantime.... Keep your beach, this is where I forget about blown Onans! 

 

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