Author Topic: OS 58 disaseembly. (Read 463 times)

dave siegler · « **on:** March 14, 2020, 02:54:24 PM »

I received a freedie OS 58 engine from 1965 i think.

Working on this just for the heck of it.
I was pretty gummed up but I got the sleeve.

While the piston is free on the crank pin, it doesn't come off.

The piston pin is retained somehow.
Need to get is apart so I can clean and replace the bearings and run it.

How does this old dog come apart?

Dan McEntee · « **Reply #1 on:** March 14, 2020, 09:27:51 PM »

The wrist pin may, and has to be, tighter fit than the rod end. It may be a slight interference fit. Try a monokote heat gun on the piston after figuring out how to push on the inside end of the rod and have tools ready. If it loosens up, then sticks, you may have to do it in stages. mark the end of the rod and piston it goes with. Old Fox .19s had a rod with a slight taper so you need to know which end is bigger. You may be dealing with this on your engine also. I understand that this was a common method on small engines at one time.
Type at you later,
Dan McEntee

James C. Johnson · « **Reply #2 on:** March 15, 2020, 02:45:18 PM »

Having cleaned and sold 150 engines in the last 6 months ... this is a problem I have faced regularly... I have stopped taking the wrist pin completely out on many engines with keepers (Jesus CLIPS) ...only the ones that are really dirty do I take them completely apart.. when the wrist pin seems to be "glued" to the rod... I first soak the piston in LA Awesome de-greaser... it works well on warm but not hot parts. try to scrub it with a small brush... then take a wood screw or drywall screw and screw it in until it won't screw anymore ... if the pin won't move or turn in the rod ...stop... next is heat ... I use a propane torch .. you will need a leather glove ... I can get away with a left hand glove because I'm right handed .. don't get too carried away with the heat... heat up the wrist pin and then twist the screw to see if you can get it to move.. if it does move but gets "GLUED" once it has cooled off ... soak it in the de-greaser again... I usually use a pair of small vice grips to hold onto the drywall screw... when turning the screw... use a pulling action too... patience is the key thing to remember... walk away if you become frustrated... I have a couple of engines that I can't get the rod off the crank pin because the wrist pin ... one is an OS 1.08... the other is a ST 61... on smaller engines I can use a metal punch and "tap" the wrist pin out using a couple of pieces of wood to support the piston... the idea here is to leave room for the pin to go all the way through... I use 400-600 w/d sandpaper to clean up the pin. On most pistons I am able to get the rod sliding back and forth on the wrist pin with the de-greaser... you have to weigh the benefits of a complete tear down or the compromise of getting the whole thing moving ... some engine parts are rare... so be careful on these older engines.. A few yrs back Scott Reese hemi-ed the head on an OS 58 and claimed it to be a great running engine in a Leo Mehl plane... Please mark the rod for orientation... I do this on every engine ... if you forget ... look at the rod big end ...the side that touched the back plate will show more wear.. look carefully.. for me ... tearing engines down has been a real learning experience ... burnt fingers.... broken cooling fins... broken rings... bearings from hell.... rounded sockets and Phillips head bolts... I love it...

Air Ministry . · « **Reply #3 on:** March 15, 2020, 09:44:52 PM »

Gees , you lot . Reading a olde magazine , last night . !

OS came out with the rear Intake 60 , and did a ' INTRIM ' 58 , based on the Max 50 . Which was a development of the Max 49 .

http://sceptreflight.com/Model%20Engine%20Tests/OS%20Max%2049%20RC%20%283%29.html looks like THAT .

Ifitsgotta hole mid hight , aft . On centerline , Thats for wrist pin extraction .
Otherwise soaking in solvent , A allen key , bent wire etc - to get wrist pin going for & aft IN PISTON . or V.c.V. , so the rod falls of the crank pin . We Hope .

Theres some DISASEMBLY videos on you tube . The 58 should be good , light, conservative timing , etc . So dont get aggro - Few parts on Ebay, too. I think .

Pieces should be similar .

dave siegler · « **Reply #4 on:** March 22, 2020, 09:34:50 AM »

The sheet metal screw in the wrist pin worked awesome. It broke loose with very little force.

The motor on its second day in the crock pot. Its cleanup nicely but real slowly.
The rings were very stuck. The was a black tar on everything. What ever oil that was I would never use it.

Worse than any Fox I ever worked on.

I cant get the rear bearing out to clean it maybe tonight

Need to make some gaskets for it. Any sources?

Gerald Arana · « **Reply #5 on:** March 22, 2020, 11:42:28 AM »

Dave,

To get that "stuck" rear bearing out, Put it in the oven at 350 for at least 15 minutes or take it out when you hear it drop out onto the "OLD" cookie sheet.

That's what I do and it works great.

Jerry

PS: I like the dry wall screw idea.

Author Topic: OS 58 disaseembly. (Read 463 times)

dave siegler

OS 58 disaseembly.

Dan McEntee

Re: OS 58 disaseembly.

James C. Johnson

Re: OS 58 disaseembly.

Air Ministry .

Re: OS 58 disaseembly.

dave siegler

Re: OS 58 disaseembly.

Gerald Arana

Re: OS 58 disaseembly.