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Engine basics => Engine set up tips => Topic started by: Scott Jenkins on May 22, 2006, 07:29:36 AM

Title: OS Max H 40
Post by: Scott Jenkins on May 22, 2006, 07:29:36 AM

Found a OS Max H 40, 2 ball bearing, in a OS 60 box at a garage sale this week end.  Scarfed it up for a 5 dollar bill. Aside from the engine being glued shut with castor oil it appears to be in good condition. During disassembly I hit a snag trying to remove the piston. It appears that the piston has flanges or bosses that totally enclose the conrod at the top. I removed the plug on the rear of the case and pulled out the teflon piston pin keeper (used a 0-80 tap) now the piston pin itself appears to be stuck may be some castor glue in the area of concern or is it something that I am not aware of. Prior to making a special tool to jack or pull the piston pin out. I thought I would check with those of you that have a better understanding of ths engine, plus I thought I would see if anyone has a piston ring (compression) for this engine laying around that they might want to part with.

Scott Jenkins
AMA 43122   

Title: Re: OS Max H 40
Post by: Andrew Hathaway on May 22, 2006, 09:30:05 AM

I've never had any of the H series, however castor gunk is universal.  If the pin is gunked up with castor heat could help get it loose.  A monokote heatgun will provide enough heat without providing so much heat that it would damage the engine.   

You may want to wait and see if there's a trick to getting it out.

Title: Re: OS Max H 40
Post by: Bob Reeves on May 22, 2006, 10:44:48 AM

Have a ST 46 I have been playing with for days with the same problem. Have had it in the crock pot for over a week, tried heat and every kind of solvent I could think of, still tighter than a drum.  My solution is going to be sending it to Frank Bowman  :)

Title: Re: OS Max H 40
Post by: SQ8s on May 23, 2006, 12:53:46 AM

One thing I do IS BOIL the engine in water for 5-10 mins. You'll be surprised what comes loose

Title: Re: OS Max H 40
Post by: Tom Dugan on May 23, 2006, 07:02:28 AM

I have boiled engines also with good results.  I recommend that you use straight water with no cleaning agents added, it could discolor the aluminum.

Thomas

Title: Re: OS Max H 40
Post by: RandySmith on May 23, 2006, 08:41:37 AM

You can also  pick  up a  gallon can of  Carb  cleaner at the auto parts store. It comes with a  dip  basket, you can  get this  clean and loose  with the  cleaner.
It is  designed  to clean  carbs  that hav e alum, plastic, brass  and  steel parts,  so  it doesn't  hurt  anything.
Or  you can  boil the engine  in the Crock pot  with  100%  antifreeze.

Randy

Title: Re: OS Max H 40
Post by: Scott Jenkins on May 23, 2006, 02:16:33 PM

I think I will boil it in water the wife would take exception to stinking up the house with antifreeze and since the fumes from the last plane I painted was said to be the reason for the demise of the parakeet. I dont want to take any chances.

Scott 

Title: Re: OS Max H 40
Post by: RandySmith on May 23, 2006, 03:51:51 PM

HI Scott

You don't  crock pot in the house  ever...Take it to the  gargage  or out  on the back porch :D

Regards

Randy