crankshaft on onan engine

[budman2 57]

Hi everyone! tearing down a 20hp onan on a 520-H, can anyone tell how to remove the crankshaft gear with out tearing up the crankshaft? I have tried a puller but it just keeps tearing out the puller bolts! any help would be appreciated! Thanks in advance,budman2

[onanparts.com 181]

9 hours ago, budman2 said:

Hi everyone! tearing down a 20hp onan on a 520-H, can anyone tell how to remove the crankshaft gear with out tearing up the crankshaft? I have tried a puller but it just keeps tearing out the puller bolts! any help would be appreciated! Thanks in advance,budman2

Time for a "special tool". I made this adapter years ago and never got around to making it perfect.....if it works don't fix it! This was a chunk of steel I made to bolt on to the gear face via the two 10X32 threaded holes already tapped in the gear. Use allen style 10X32 bolts as they typically are grade 8. Cheap or low grade screws/bolts will break! 20 years on these and they are in perfect shape.

Grind a small notch on the back side for clearance of the gear woodruff key. You can see where it sticks out slightly in the second pic. Put the flywheel bolt back in all the way for the puller bolt to bear against. The gear is a press fit and on VERY tight. Use of grade 8 bolts is critical! :)

 

 

[budman2 57]

Thanks man! no wonder I coudn't get it off! That looks like a heavy duty tool!!!!!!!!!!!!

[onanparts.com 181]

3 hours ago, budman2 said:

Thanks man! no wonder I coudn't get it off! That looks like a heavy duty tool!!!!!!!!!!!!

You're welcome! The gears are heated prior to installing them. Very tight interference fit! Never want to overheat the gear though. Spit temp works, when your spit balls up and rolls off it's hot enough!

You really need to make up something with a hole in the middle and enough to grab onto from the backside. Any style puller will work in most cases if you have something to grab onto! :) No heat is used to remove the gear! Pull cold, install heated.

 

Years ago I started a project for an inexpensive puller adapter like the one shown. Might have to move it from the back burner to the front. Just some big washers stacked and tack welded. As I recall I needed to open up the washers ID a bit. Here is a couple pics of the first one. Onan had the keyway in two different places over the years so the plan is/was to make two notched areas.

[budman2 57]

Can I ask where you got the heavy duty puller! Thanks budman2

[onanparts.com 181]

6 minutes ago, budman2 said:

Can I ask where you got the heavy duty puller! Thanks budman2

It's a Posi Lock model 106. I've had it and a couple other versions now for about 20 years. 2 jaw, 3 jaw etc. This is the exact model in my pics.

https://www.napaonline.com/en/p/POL106

[budman2 57]

Thanks much! now I can get that gear off! budman2

[onanparts.com 181]

4 minutes ago, budman2 said:

Thanks much! now I can get that gear off! budman2

There are other pullers that will do the same job but for much less. Just needs to be a quality, not imported, tool. The posi lock is the cats meow though. Jaws can't slip etc. :)