WRISTPIN REMOVAL HELP

[Tommo]

I am rebuilding a Johnson 4hp 1985. I have dismantled the entire engine but have ran into
a problem. I need to remove the Wristpins to clean the bearings but have been unnsuccesful. I have removed the circlips and have devised a cradle and pushing rod to try push the wristpin out. I have tried heating the piston then hitting the rod with a hammer. But the wristpin hasn't moved. I believe there is some rust that is restricting the removal.

Anyhow, can anyone think of a way to remove the wristpins? I am willing to somehow cut the wristpins out and buy new ones, salvaging the bearings and piston. The reason I need to remove them is the bearings are stiff and the conrod doesnt move freely. Is there any other way to fix this restriction.

Please Reply as I am desperate for help.

Thankyou

 

[desertgoldhound]

Re: WRISTPIN REMOVAL HELP

Have you tried an arbor press

 

[desertgoldhound]

Re: WRISTPIN REMOVAL HELP

If you havent check with your local parts stor the last time I needed one they rented one to me.

 

[R.Johnson]

Re: WRISTPIN REMOVAL HELP

If the wrist pin is rusted to the rod, what does the crankshaft look like?

 

[F_R]

Re: WRISTPIN REMOVAL HELP

The wrist pin is a press fit in one side of the piston and a slip fit in the other side, which allows it to come and go with expansion/contraction. The slip fit side is marked with some sort of marking, like an L, or a prick punch mark, or something. Not all are the same so I can't tell you exactly what to look for-but it's there.
Use an arbor press to push it out through the tight side. TIGHT side down, loose side up. It's not rusted into the tight side-no room for rust to get in there. But "possible" corroded into the loose side.
Since you don't have an arbor press, take it to an automotive machine shop and have them press it out. They might have a minimum charge, but it won't take a minute.

 

[Tommo]

Re: WRISTPIN REMOVAL HELP

Thanks for the replys,
On Second thoughts it probably is corrosion rather than rust. Commander the crankshaft looks fine.

So I need an Arbor Press, Im in Sydney should I take the pistons to a Car Mechanic or a outboard service place. I am not exactly sure what you mean by automotive machine shop?

Thanks

 

[F_R]

Re: WRISTPIN REMOVAL HELP

Well, here an automotive machine shop is the place that rebuilds automobile engines as well as refinishes brake rotors, and such. However, automotive general service shops and outboard shops should also have an arbor press. It's not an uncommon tool at all.

 

[desertgoldhound]

Re: WRISTPIN REMOVAL HELP

Here check ebay out here is a link already filled in the search. Should be cheaper to buy one then to have it done for you.

http://search.ebay.com/arbor-press_...QQfsopZ1QQkeywordZonQQsacatZQ2d1QQstrkwZpress

 

[Tommo]

Re: WRISTPIN REMOVAL HELP

Thanks for the help guys, ill tell you how I go.

 

[mikesea]

Re: WRISTPIN REMOVAL HELP

what i have done is take a piece of lumber,drill a hole slightly larger than the wrist pin,remove the clips,i have used long sockets,scrap steel rod about the size of the wrist pin and laid the piston on the lumber ,wrist pin to fall into hole,hit the wrist pin from opposite dide using mallet and anything you find round size or bit smaller than wrist pin, omc made a jig which is made of plastic,like a bunch of U's with holes to accept all of their pistons sizes,it is common for shops to hit em out with mallets, it is a bit harder for the pressed pistons but ive done it many times,just hit it the right way