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Author Topic: ST60 wrist pin question  (Read 1557 times)

Offline Randy Powell

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ST60 wrist pin question
« on: June 22, 2011, 09:30:44 AM »
I have an ST 60 I was attempting to fix. I got the cylinder out pretty easily with heat (as I've always done) but the wrist pin appears to be frozen in place. I don't want to pound on the thing and I haven't been able to pull it out. So, I thought the next step would be to heat the engine up in the oven and see if that breaks it loose.

Any other ideas?
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Offline RandySmith

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Re: ST60 wrist pin question
« Reply #1 on: June 22, 2011, 09:59:49 AM »
I soak them in penetrating oil over night then use heat, Some people cook them in antifreeze.
You can try either, That will normally let you remove the pin .

Randy
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Offline EddyR

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Re: ST60 wrist pin question
« Reply #2 on: June 22, 2011, 11:11:50 AM »
Randy  I bet that motor was way down on power. Many times I have people tell me there ST/40-60 is not running well or not very strong. I suggest to them that the pin is frozen. Most do not believe it and keep on running the motor that way. Very common problem in 20+ year old  ST/40-60 motors.
 RandySmith probably has seen hundreds like that.
EddyR
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Offline RandySmith

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Re: ST60 wrist pin question
« Reply #3 on: June 22, 2011, 12:39:22 PM »
Quote from: Ed Ruane on June 22, 2011, 11:11:50 AM
Randy  I bet that motor was way down on power. Many times I have people tell me there ST/40-60 is not running well or not very strong. I suggest to them that the pin is frozen. Most do not believe it and keep on running the motor that way. Very common problem in 20+ year old  ST/40-60 motors.
 RandySmith probably has seen hundreds like that.
EddyR

Yep I have seen so many motors with the wrist pin galled from being either froze up  or burned crispy and has hard carbon built up on both sides of the pin, That makes the rod  really hard to get off.! !!
many times the top rod busing is also toast

Randy
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Offline Randy Powell

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Re: ST60 wrist pin question
« Reply #4 on: June 22, 2011, 12:46:36 PM »
Yea, I inherited this engine and have never run it. It was pretty cruded up when I go it. I heated the case and was able to get the cylinder out. I tried putting it in a crock pot with anti-freeze overnight, but that didn't do anything. I suppose I could soak it in parts cleaner overnight next. I may try the oven trick or just gingerly heat the piston with a torch to get it to expand enough to get the pin out. I have enough parts (pistons, cylinders, rods and wrist pins) to probably make one good engine. Luckily, I has a complete, unopened gasket set, several new rings and an assortment of other stuff.

As I say, I hope to get one good engine out of it.

I was just hoping that someone had some slick trick to getting the pin out. But it sounds like I'll just have to do it the old fashion way: keep working it until it comes out.

The engine is planed for a large Classic plane if I can get it running.
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Offline rustler

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Re: ST60 wrist pin question
« Reply #5 on: June 22, 2011, 02:53:38 PM »
I had one of these recently, the pin was IN and determined not to come OUT. The engine has a hole for extraction in the back of the c/case.
I lowered the piston to bdc, so it was clear of the hole. Then mercilessly drilled across the case so there was a matching hole at the front.
It was then a simple matter to push the pin out from one side with a suitable drift. I'm not saying how suitable!
Thoroughly clean everything afterwards!
« Last Edit: June 23, 2011, 02:18:44 PM by rustler »
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Offline Randy Powell

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Re: ST60 wrist pin question
« Reply #6 on: June 22, 2011, 03:59:58 PM »
Hmm, it might come to that.
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Offline Bootlegger

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Re: ST60 wrist pin question
« Reply #7 on: June 22, 2011, 04:44:26 PM »
 :!     Mister Powell I sent ya' a P/M... ~>
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Offline Peter Nevai

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Re: ST60 wrist pin question
« Reply #8 on: June 22, 2011, 11:38:56 PM »
Get a piece of wood and shape it like in the image, with a hole drilled a tad larger than the wrist pin also like the image. Rest the piston in the channel line up the wrist pin in the piston with the hole in the wood and use a cut nail or screw small enough to just fit in the wrist pin hole. Use a clamp or vice to press out the pin.
« Last Edit: June 24, 2011, 11:09:56 AM by Peter Nevai »
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Offline M Spencer

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Re: ST60 wrist pin question
« Reply #9 on: June 23, 2011, 12:51:33 AM »
Is it a hollow pin where you can put an esiout tru the case hole to give it a twist and ease it out ?

Often youd need to soak in acetone or the like for even ten days to soften carbon , if thats whats holding it .
Some engine or carb shops have ' hot tanks ' set up so there O.K. for aluminium.
Or Caustic Soda will disolve everything but the pin. Probly not the best economics .
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Offline Randy Powell

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Re: ST60 wrist pin question
« Reply #10 on: June 23, 2011, 09:55:44 AM »
I'm current soaking it in Penetron. I plan to heat the thing up tonight then try to tap it loose. I'll report how it works.
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Online Jim Kraft

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Re: ST60 wrist pin question
« Reply #11 on: June 23, 2011, 07:55:24 PM »
I had a Tigre 46 like that. I tried about everything I could think of to get it loose. I finally did as said above and drilled a hole on the front side and drove the wrist pin out with a punch. I then tapped the hole in the front of the case for a short 4-40 socket head bolt. I did have to make new pads for the pin out of some teflon, as I kind of ruined the brass ones with all my tugging and pushing.
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