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#1 buxy OFFLINE  

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Posted January 20, 2012 - 09:00 PM

Just getting into small engine repairs. O what Fun!!! Inherited a Case 444 and a Case 448 lawn tractor. Both have Onan 18 hp motors. The 448 is running but surges (governor issues perhaps?) and the 444 i am using for parts for now. My question... as i stated i am using the 448 tilling garden in summer and pushing snow now but when i was doing tune up and checking things out on the motor i noticed there is no condenser or breaker points. The cover is there and the plunger but thats all folks. Any ideas how it is running not so bad other than the surge. Could this cause the surging? She starts great!?!:confuse:

#2 GTTinkerer OFFLINE  

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Posted January 20, 2012 - 09:13 PM

After over 20 years in the small engine business I hate to admit that the only thing I have even done to an Onan is replace it with another brand. That will probably change soon since I am picking up a Sears with the Onan 16 horsepower engine plus a spare engine at the end of next month. Hopefully the 2/29 thing won't give me bad luck.

I am sure someone will be along soon to answer your question correctly but I will take a guess and say either Onan went to electronic ignition or maybe someone added one of the "Atom" style pickups.

#3 buxy OFFLINE  

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Posted January 20, 2012 - 09:19 PM

Hmmm. Food for thought and some more research to do . Thx

#4 MH81 ONLINE  

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Posted January 20, 2012 - 09:22 PM

:welcometogttalk:

Unfortunately, the only thing I know about Onans is how sweet they run when they are tuned up right. Hope the right guy comes along soon with your answer.

#5 CASENUT OFFLINE  

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Posted January 20, 2012 - 10:17 PM

Well I have a couple of onans apart right now ...broken rods. So, let me being with the surging...the intake manifolds on these are 'famous' for becoming loose, in that they are a 2 piece design they 'suck' air as the bolts loosen. Were I you, I would remove the carb, get to the intake namifold, remove it take it apart clean the livin daylights out of it...put it back together using some quality RTV sealant I like the high temp stuff, but you'd probably be ok with ultra black, secure the screws with some med strength locktite put it back together 'air tight' and do the same for the mount to the engine and carb mount. I believe that will cure your 'surging' issue. I will have to dig into the ignition system in that it has been several months and I cannot remember...Good Luck and those are stout machines...

#6 dstaggs OFFLINE  

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Posted January 20, 2012 - 11:19 PM

Sure hope I never have to work on mine LOL

#7 cookiemonster OFFLINE  

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Posted January 21, 2012 - 12:19 AM

Yes, what he said. Surging is normally carb issues. Intake leak or not getting a good spray (dirty).

#8 CASENUT OFFLINE  

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Posted January 21, 2012 - 12:59 AM

Sure hope I never have to work on mine LOL


Do we share the same hobby? ha ha ha...not likely

#9 mjodrey OFFLINE  

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Posted January 21, 2012 - 05:12 AM

buxy,welcome to the forum.Glad to have you with us.

#10 buxy OFFLINE  

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Posted January 21, 2012 - 12:13 PM

Thx all. Re: Surging...Took off intake manifold and did a carb cleaning and re-build. Manifold seemed airtight and put things back together. She starts and runs way better (After setting idle and fuel mix) but still surges. I changed the governor spring location to each setting (3 diff spots) and the tightest setting seems best. Still not great tho. Maybe a tear down and chek the governor but its a big job!??!

#11 ramdeesl OFFLINE  

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Posted January 21, 2012 - 01:47 PM

Yes, what he said. Surging is normally carb issues. Intake leak or not getting a good spray (dirty).

Ditto. In my experience with these engines surging is cured by pulling the carb apart and blowing out all of the tiny ports with carb cleaner. 9 out of 10 times thats your problem. :smile1:




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