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O.S. FS-91S Cam Cover Stuck

Old 05-24-2020, 11:37 PM
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Default O.S. FS-91S Cam Cover Stuck

I have an O.S. FS-91 Surpass that was stored indoors without after-run oil for about 9 or 10 years. The carb was stuck and could not rotate the crankshaft.
  1. Took the glow plug out and put nitro in the piston and carb and let it soak overnight. This loosened up the carb and could rotate the crankshaft, but no compression.Took of the valve cover, and the exhaust and intake valves were stuck.
  2. Let it soak overnight in mineral spirits unheated with the cover plate in the back off, valve cover off, rocker off, and push rods off. I tried to get the Cam Cover off but it will not budge. I even broke the ears for the mounting holes trying to pull or pry it off.
  3. Put it in a crock pot full of ethylene glycol antifreeze on the low setting for 4 hours with the same stuff disassembled as in step 2.
  4. All valves are rocking when I rotate the crankshaft except the intake valve closest to the Cam Cover.
  5. Applied heat gun at about 275 deg F to the bottom of the stubborn intake valve's push rod cover. I hear a "pop" and the valve rocker moves down but will not move back up when rotating the crankshaft. In other words it's still stuck. I repeated several times with the same result.
So, I gave up on trying to soak and heat it and tried to get the Cam Cover off and it will not cooperate.
What should I do to get that Cam Cover off? Or should I try something else?

Thanks for any and all help!

Old 06-16-2020, 10:29 AM
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Hey Joe.... What you explain happened with me too.... the cam cover would not budge. This is what I did

I clamped the engine tightly in a vice so it would not move... Tightening the engine directly in the vice is not recommended, so I had wooden planks held by the vice in between the engine and the vice. On the wooden planks I made space for the engine mounts to go in.... then tightened the vice so engine would not move. Then I removed the two bolts holding the cam cover. The cam cover of OS FS91 has two kind of ears... .what you need to do is heat the engine body and gently tap on the ears, so that you can rotate the cam cover..... once you are able to rotate to cam cover you can then slowly keep rotating till it comes off... It worked for me and I got the jammed cam cover off the engine without any damage to the engine or the cam cover.... Be easy on the cam cover ..... this technique worked for me ... hope it works for you .... best

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