Onan P Series Governor Ball Replacement Procedure.

[Duramax7man7 506]

Hey Everyone. 

 

 I found this procedure on the internet and wanted to make sure that it was posted here as well. This was my replacement though. 

 

 I have a 1990 520h with the Onan P220G-i/ 10955c that had a plastic governor ball spacer under the governor cup. The symptoms were mainly hunting of the throttle and when hot (about 30-45 minutes into operation) the rpms of the engine would rev well past the designed 3600 rpms as high as 4000 rpms. I tried everything I could think of including the memo put out by Onan to remove both governor clips from the governor rod that attaches the throttle to the governor arm, slightly pinch them with pliers to tighten them up and then reinstall. Which did seem to help for a bit at first. but to no avail wouldn't fix the issue. I had some time and decided to document the important aspects of this procedure for those that wanted to attempt it themselves. If I forget anything please feel free to mention it in response as it only benefit the thread.

 It's said that the engine needs to be removed for this operation but I didn't want to do this. So I left the engine fully mounted for this method without any issues and it didn't seem anymore difficult as all bolts and fasteners can be reached easily IMO. 

 Steps to take are:

 

1. Warm the engine

2. Drain the oil. (I raise the right rear tire up to full drain as much old oil as possible)

3. Shut the Fuel valve off on the tank

4. Disconnect the battery and Fuel/ vacuum lines from the engine. 

5. Remove the air cleaner and box completely (I closed the choke all of the way and stuffed clean paper towel into the top of the carb and then covered it with clean plastic sandwich bag and zip tied that down)

6. Remove all wires from the coil and voltage regulator

7. Remove all bolts from the front shroud (sides top and bottom) including the one by the coil on the top of the engine block (by the valve covers)

8. Drain the fuel line from the fuel pump as best as possible and then remove the two fuel pump bolts (Hex head allen wrench type) and vacuum line from the back of the fuel pump.

9. You will need to gently pull the bottom of the shroud out at the bottom, lift up on it and then slightly lift up on the lip of the rear cylinder shroud to get the coil out (or remove the coil first then follow same procedure)

10. Pull the four fly wheel grill bolts, then the flywheel

11. Carefully remove the Stator, Spark Ring and Spark Module and set aside or place in safe spot on top of the engine and secure so it doesn't fall. 

12. Remove all four timing cover bolts as well as the nut at the top and use a rubber mallet and some pressure to carefully remove the timing cover to expose the governor and crank gear, etc...
13. Lift the left rear (drivers side in a car) tire up enough so that the engine tilts backward so that the governor balls don't fall out when you take off the cup.

14. You will need to push the governor cup in and gently pry out the retaining ring from the cam end exposing the spacer and gov. balls. Set them and the ring aside in a clean safe space. 

 This is where you should be at this point. 

 

 

 

 

15. Next just grab the old plastic ring and with your fingers and give a twist back and forth from side to side while pulling on it and it should slip right off. Here is the old spacer next to the new spacer. You need to clean the gasket surfaces on both the block and the timing cover really well. I used fine cut sand paper and break cleaner and then blew the whole thing out really well. 

As you can see I went ahead and replaced the old oil seal with a new one while I had it all apart and drained. The timing Cover oil seal part number is 0509-0040 and if you want it, the rear oil seal in the bearing plate is 0509-0041. 

 

 

NOTE: one thing to keep in mind that is very important is to NOT lose the pivot ball bearing under the bottom of the vertical governor shaft inside the timing cover. If you didn't realize that it slipped out, the guide for the cup on that shaft will not be centered on the hole on the  
 

16. Clean the cam surface where the new spacer will go really well and then wipe clean with something like Rubbing Alcohol or brake cleaner on a clean paper towel or shop cloth. Then apply a THIN Layer of RED THREAD LOCKER!!! not to much. you don't want it to end up somewhere it doesn't belong.  
 

 

 

 

 

17. The new spacer should fit on there just fine. Align the spacer so that one of the spacers is in the center of the space on the left in the block to avoid the closest ball bearings trying to get into that spot. Bad thing could happen if otherwise if a ball gets out of wack throwing everything off center and unbalanced. Once aligned properly, push on and then lightly tap the spacer the rest of the way on using a rubber mallet. 

LET THE ENGINE SIT OVERNIGHT OR LONGER SO THAT THE THREAD LOCKER HAS TIME TO SET.

 

 

 

 

18. in the mean time.... Continue on to reinstall the ball bearings making sure to space them evenly apart in the spots of the spacer.

 

 

 

19. Replace the governor cup, cup spacer and ring and align the hole with the plastic spacer so that it aligns with the pin on the inside of the timing cover, next to where the governor shaft and guide are. Very important. 

 

 

 

 

 

20. Notice the hole with spacer is perfectly horizontal and lines up with the pin next to the forks of the governor shaft. Also notice that the forks are centered perfectly over the hole. If the ball bearing was missing from underneath the governor arm shaft in that bottom section, the forks would seem to low. Also notice the clean surfaces and the gasket already in place at this point as I prepare to reinstall the timing cover. 


 

21. Oil or grease up the crank and use some on the lip of the oil seal, you can even clean the surface really well first and then place a piece of electrical tape all of the way around and cut it so that it meat right at the other end of the tape and is flat. Then grease and install the cover. 

 NOTE: It is recommended to use some teflon tape or from a tube on the threads of the lower bolts that are closest to the oil pan to aid in avoiding any seeping of oil from those locations as well as a tiny bit of oil or grease. Make sure not to lose the copper washers as well. The torque specs for all of these bolts and nut are 25-27lbs. I went with 26 lbs. 

 

 

Sorry, no more photos after this. I wanted to show the most important parts of the core of the procedure. You all can figure the rest out.  

 

The last thing to do is to button everything back in the reverse order it was taken off. Don't forget the flywheel cap screw is 55lbs. 

 

I hope this will help someone in the future cure their over revving engine. It's not really as daunting as it seems. 

Edited April 7, 2017 by Mastiffman

[Ed Kennell 39,058]

Excellent tutorial.  

[aHorseofCourse 261]

  Awesome job.  Interesting how Onan did the governors, never had one apart myself

[boomers_influence 106]

mastiffman

in the second to the last pic. it appears that 

the governor cup hub should have been replaced.

those DIVOTS do not belong there.

 

club

i did supply the parts for this repair.

 

thank you. boomer ( the used onan engine parts guy, also NOS and new )

 

[Duramax7man7 506]

Thanks Boomer. I didn't give you any props because you told me that you will "never do business with me again" right before you hung up the phone on me when we were discussing how the return of the exhaust manifold that didn't work out, was going to happen.

 Personally I don't see how those divots will affect anything. I think that the lighting in the photo is exaggerating them as I didn't feel anything much when reassembling it all. I don't think that a couple of thousands (max) will make the engine governor less effective. It runs great after the switching out of the spacer. So thanks for that suggestion.  

[Mocrazy1 5]

I know this is an older thread, but I'm attempting this job now. I wanted to add that the torque value of 25-27 ft lbs, I believe, is Incorrect. I think that is for the bearing side of the engine, not the Timing cover. I believe that torque value is 8-10 ft lbs. Labeled gear case cover. If I'm mistaken, please let me know.Thanks  

[Duramax7man7 506]

You are correct! I did torque them properly and actually typed that in wrong... 

Thanks for clarifying that. It's appreciated. 

Andrew C.

[Mocrazy1 5]

Thanks for the very complete article, Andrew. I tightened mine to 10 then 20. I stopped at that point, I thought it was getting too tight. Did some research and backed them off and retorqued to 10 ft lbs. I'm hoping it didn't affect the gasket or anything. 

[Bill D 1,992]

Is anyone reverse engineering these flyball spacers.  Since Onan doesn't offer these new, how much longer before the supply runs out?  I have a neighbor that could make some for me using one I have as a template.  Would there be any intrest?

 

Bill

[Arthur England 5]

Is the problem that the slots for the balls wear or that the spacer slips on the shaft? If its that the balls become loose in the spacer, would it be posible to move the balls to the other five slots?

 

Arthur

[Duramax7man7 506]

On 8/3/2018 at 10:44 AM, Mocrazy1 said:

Thanks for the very complete article, Andrew. I tightened mine to 10 then 20. I stopped at that point, I thought it was getting too tight. Did some research and backed them off and retorqued to 10 ft lbs. I'm hoping it didn't affect the gasket or anything. 

My pleasure. Sorry for the mix up. I don't think that it would affect the gasket to the point of not sealing. They only compress to a certain point and it's probably only couple of thousands. worse case scenario I believe that you could use a good hi temp gasket seal/ maker along with the gasket if you catch a leak. Or get a new gasket. I wouldn't worry to much about it at this point. 

On 8/4/2018 at 2:03 PM, Bill D said:

Is anyone reverse engineering these flyball spacers.  Since Onan doesn't offer these new, how much longer before the supply runs out?  I have a neighbor that could make some for me using one I have as a template.  Would there be any intrest?

 

Bill

I think that is a great idea! I'm positive that there would be interest. Maybe not a super high demand but deff a small nich. 

13 hours ago, Arthur England said:

Is the problem that the slots for the balls wear or that the spacer slips on the shaft? If its that the balls become loose in the spacer, would it be posible to move the balls to the other five slots?

 

Arthur

No, it's the spacer that starts to slip on the shaft and that's typically only after the engine heats up enough to allow the spacer to swell a bit and start spinning. I don't know if it would to hit the cam with some rougher grit emery clothe, clean up the spacer with some very fine if needed and then use some extremely high strength and ultra high temp resistant thread locker and let that sit for a couple of days or more to harden before use. Or do the same and use a thin coat of JB weld to do it... Which might be better as it can withstand constant temps of 500*F and a max of 600* for short periods. 

 JB Weld "Extreme heat" can withstand 2400*F. 

Edited August 6, 2018 by Mastiffman

[Mocrazy1 5]

I think my gasket will be ok Andrew, it's new. The engine is going back in a John Deere 318. Maybe, JB Weld would work, but you'd probably have to remove the cam if you ever needed to remove the spacer (after JB Weld). I used Loctite 272 and primer 7649. Expensive, but I don't want to do it twice. Here's a pic of my spacer, I was fortunate enough to find a steel one on a cam I purchased. Why any company would install a plastic part, under stress, in an engine is beyond me!

[Duramax7man7 506]

Excellent! Good to hear. yeah the red loc-tite should do the  trick for the metal spacer. and WOW, snap that sucker right in half, huh? My old one would only start slipping after 25-30 minutes of mid summer mowing/ use. It was still intact. But the inside bore was blackened from spinning. yeah the steel ones are floating around. You just have to watch for them and make the move when you see them. 

 The good thing is that the engine doesn't have to be pulled from the tractor to do the job. Pop all the stuff off right there, switch out the spacers and bang it all back together with a torque wrench and off you go. 

Really glad that someone is getting use out of this write up. 

[Mocrazy1 5]

No easy task on the John Deere 318. Engine has to come out. I'm decarboning the heads and piston while it's on the bench. PO said it would start revving after 20 minutes or so. I drove it, to park it, and surprisingly it didn't do it to me. On another forum a member said to try Mercury Quicksilver aerosol spray, with a plastic scraper, for piston tops and heads. Soak for a couple sessions and it really eats up carbon. Did you ever remove the intake valve seals? I'm replacing them, but can't find a method so far. I believe they just pull off from the valve box side. I know the manual says "once you pull the valve out of the original seal, you have to install new seals". Before and after cleaning on intake valve. 1000 hours on machine. 

 

[lynnmor 7,361]

I just got an abused, approximately 1989 P220 running after replacing a loose valve seat and grinding all the valves.  After the carb adjustments it ran fine, so I did a tour of the woods and it started revving, so I guess the governor split.  Is that the symptom of a split plastic part?  I didn't open the engine yet so I don't know if it is plastic or steel, have any idea when they changed?

[Mocrazy1 5]

I'm not sure what spacer yours has. At some point they switched over to a plastic one with an extension tab that rides in the gear notch. That way it can't slip on the cam flange. Some of the cam gears might not have the notch, so you're better off opening yours up to see what you have.I'm still not sold on plastic being used, so I found the steel spacer. Maybe some research can supply you an answer. 

[lynnmor 7,361]

Thanks for the reply, that is good information.  I have been searching for any part, using what part numbers I can find and am not having success on finding anything.  Yes, I need to pull it down, but with no available parts it will be stuck there till something turns up.  I have a tool & die shop and can make the part if necessary, but that would take a lot of time that currently I don't have.  I could machine a notch for the tab, after pulling the cam gear.  I'll contact Boomer to see if he can help.

[Mocrazy1 5]

Yes I'm corresponding with boomer for a gasket kit. He's quite knowledgeable,  helpful, and affordable. Good luck.

[TC10284 111]

This might be a stupid question, but is it possible to use thread locker on a plastic spacer without the extended tab, and/or somehow fashion a plastic tab that would fit in one of the empty spacer slots? 

 

I have a couple 520's with this plastic spacer without the extended tab. 

[Mocrazy1 5]

I'm not a fan of the plastic, after seeing the flange cracked on mine. I found a metal one on fleabay. Mine was on a John Deere 318. Probably a more involved job, being the engine has to be removed. I think on a Wheel horse, you can, maybe just lift the flywheel side of the engine. If the plastic one is all you can find, you'll have to go with it. I used, a quite expensive thread locker product, and primer, to clean everything. Like $40 for the two products. I wanted to make sure they would set up permanent like. Good luck.

[lynnmor 7,361]

I would make a real effort to find a metal one and then super glue it in place.  I did replace mine with a plastic one that had the tab and super glued it as well, Boomer helped me out.

[Mocrazy1 5]

I'm sure it should be fine. Onan should have had a class action suit against them. That's no cheap repair. Nobody would tackle it, for the PO, of my John Deere, so I bought for a good price. I still love the sound of the Onan. Kinda like an old VW.

[bc.gold 3,403]

Plastic retainer no tab.

 

[TC10284 111]

18 minutes ago, bcgold said:

Plastic retainer no tab.

 

 

What are you showing us? 

[Mocrazy1 5]

1 minute ago, TC10284 said:

 

What are you showing us? 

That gear doesn't have the gap for the extended tab. Here's my spacer before the replacement. Did the one shown, only have 3 ball bearings? Be sure not to loose the little ball bearing, about the size of a bb, inside the area, the governor arm rod, seats in the timing cover. It keeps the fork centered. I'm not sure if that's the correct terminology for all the parts.