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Onan Governor Fightin With Me.


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#1 dropped82 ONLINE  

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Posted May 26, 2014 - 08:31 AM

Few months back, I got this '85 Case 448 with a b48m Onan in it. Tractor has 391 hours on it and the engines runs like it does. Not a lick of knock, tap, or smoke. The problem is the engine speed. When I first got it running, I could only get 2500 rpm's max out of it. Ran great at that speed and the governor held that under load like it should. So, I played with the throttle cable and also replaced the spring with another I had laying around. Now when I get enough tension for 3400, it wants to over rev when I move the throttle up too fast. It also is inconsistent with engine speed. Sometimes it'll run 3400. Sometimes it'll only run 3000. I can't figure out what I'm doing wrong. Is this an internal issue? Thanks.

Eric

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#2 KennyP ONLINE  

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Posted May 26, 2014 - 11:18 AM

That spring could be the wrong tension for the governor to work right. Do you have the spring in the right holes per the manual?


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#3 dropped82 ONLINE  

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Posted May 26, 2014 - 12:43 PM

Yes, they are in the correct holes. I at first thought the same thing. I robbed the spring from my best running Onan. It still did the same thing. I have a complete parts engine. So I've had the luxury of parts swapping. Unfortunately nothing has worked yet.

Eric

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#4 superaben OFFLINE  

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Posted May 26, 2014 - 02:51 PM

I'd say two things:

 

One, go back to the original governor spring or (if you have doubts about it) buy a new one.

 

Two, I'd check to see if the intake manifold is sealing.  That thing should have an intake manifold that comes apart in two pieces.  I'd check to see if the silicone ol' Onan coated it with is still doing its job.  Usually the symptom of that manifold not sealing is the engine surging and not idling well, but that is usually one of the biggest problems with an Onan.

 

Ben W.


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#5 dropped82 ONLINE  

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Posted May 26, 2014 - 03:42 PM

It idled and runs great. I've managed to get a consistent 3150. I will manage with that currently. Maybe the more use it gets, the better. It sat for 3+ years before me. Could it be possible things are gunked up? I understand, the onan uses ball bearing type weights that spread as they spin faster? Also looks like it doesn't require a complete tear down for repair like the kohlers. I've done 2 internal repairs on kohlers already in the last 3 months. Thanks again.

Eric

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#6 KennyP ONLINE  

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Posted May 26, 2014 - 03:44 PM

Have you read this in the service manual?

Onan Governor.jpeg

 


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#7 olcowhand ONLINE  

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Posted May 26, 2014 - 04:06 PM

The "spider" that separates the balls under the governor plate may have busted apart.  This lets the balls all gather in one spot rather than evenly spaced.  It makes the governor unpredictable.


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#8 dropped82 ONLINE  

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Posted May 26, 2014 - 08:55 PM

Being unpredictable is what it is doing. When I first start it up with the throttle at idle, it'll rev up some then fall idle. If I move the throttle at a slow steady pace, its fine. If I move it fairly quickly, the rpms take off unless I bring it back to idle immediately. Is this spider tough to replace? I know the flywheel has to come off. Which means the engine has to be pulled, I would imagine. I wonder if it shares the same spider as the b43m. I have a complete parts engine. Thanks for the help!

Eric

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#9 KennyP ONLINE  

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Posted May 27, 2014 - 12:10 AM

Look in the parts manual, but I believe they will interchange.



#10 dropped82 ONLINE  

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Posted July 20, 2014 - 08:06 PM

For anyone watching this thread, here is my problem. I finally tore into it. Daniel, you were spot on. This thing grenades. Good thing is that everything is still behind the cover and not in the rest of the case. Now to hunt for another spider.

uploadfromtaptalk1405904794034.jpg

Eric
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