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AlexH

1992 520H idle/running rough.

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AlexH

Hey yall. So I bought a 92 520H yesterday. Lady said it hasn't ran in 5 years just parked in garage. I drained fluids and changed them all. New spark plugs, battery, battery cables, fuses and relays. Got it started up and it was surging a little bit. After a few minutes mowing it leveled out and ran fine. Well a little later I changed oil and filter and added seafoam to fuel. Started up and ran great a few minutes then started to blow white smoke and backfiring and started surging bad. Now only will run with choke adjustment. Any ideas? 

20210717_120338.jpg

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WHX??
Posted (edited)

:WRS:

Start with a carb cleaning. Your well intentioned maintenance may have dislodged some crap. Did you replace fuel lines/ filter. May have sat with ethanol in it's go juice. Looks like you might have? 

Edited by WHX24
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AlexH

I replaced the filter but not the lines.. I'll tear into the carb this week and see what I find! Thanks. 

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WHX??

Warn ya the carb is a :bitch:to get off. Have to pull the intake manifold so I usually do mine in place. Others will be along to welcome and tell how they do it. Yeah replace the fuel lines... ethanol gas can wreak havoc on rubber components including rubber components in the fuel pump. 

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oliver2-44

:text-welcomeconfetti:

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lynnmor

:text-welcomeconfetti:

 

You can first try cleaning the carb while it is in place.  Before removing the carb top, take a photo of the linkages and keep the choke shut as much as possible to keep things and dirt from falling in, then clean it out as best you can.  Those air box screws will need some blue thread locker. If that cleaning fails, it is time to pull the manifold and do it right.  Use only genuine Onan gaskets for the manifold and exhaust, others can fail.  Tell us the hours on the engine to see if we can suggest other maintenance.

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AlexH

It's got almost 1200 hours on it

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AlexH

Do you happen to know where I can find those oem parts? Looked online and can't see to find a carborator kit or anything. 

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lynnmor

With 1200 hours, the valves need adjusted and the heads should have the carbon removed.  Parts can be found at onanparts  and  Colburn.

When you remove the exhaust it would be a good time to glass bead and paint it with Rustoleum High Temperature paint.  The intake needs to be carefully inspected for leaks at the seam and for cuts from the heat shields.  You need the Onan Service Manual for the bolt torque specifications as well as other information.  Return here with questions.

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WheelHorse520H
On 7/19/2021 at 8:40 AM, WHX24 said:

Check with @onanparts.com Onan Parts.Com, Rebuild Parts for Onan engines

Looks like he went fishing tho. 

Yeah, I had to order my gaskets for the “500 hour cleaning” at the 650 hour mark from Colburn because it was going to be like a month before they even started with my order.

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