Author Topic: Tired OS MAX 35S (Read 2805 times)

Manuel Cortes · « **on:** March 09, 2006, 03:35:30 AM »

Hello all:

I´ve a well used OS MAX 35S who now is low on compression.
I love the 424 given by these engines.
Is rebuilding it possible? Changing piston-sleeve? Chroming? The main bearin is OK, and the overall condition of the engine is excellent.
If some person knows an estimate of the cost, will be very useful.

Thanks for helping and congratulations, good job!

Manuel.

Andrew Hathaway · « **Reply #1 on:** March 09, 2006, 12:14:36 PM »

Brian Gardner in Australia has had some ABC piston/cylinder sets made for these engines. Last I heard he was sold out but was taking names for another order.

I can't make any comments on quality or how well they work as I haven't received mine yet, but the pictures I've seen look good. There are links to photos and reviews over at stuka stunt.

ash · « **Reply #2 on:** March 09, 2006, 01:42:02 PM »

Another thing you can try as a temporary fix is to "grow" the piston. I did ths on a Max-III 20 and it worked well. Basically it involves baking the piston in the oven for about an hour. The metal in the piston is partly of a crystal structure that can be converted by heat and in this case it ends slightly expanded, so the piston is tighter in the liner.

I don't have better info than that on me right now, but someone else with expertise can give details.

Garf · « **Reply #3 on:** March 11, 2006, 06:34:45 PM »

I have 4 short runs on the Brian Gardner ABC P&C assy. It seems very promising.

Manuel Cortes · « **Reply #4 on:** March 13, 2006, 05:56:06 AM »

Thanks a lot for your suggestions.
I´ve emailed to Brian Gardner, and probably will try heating the piston.

You have a friend in Spain!!

Manuel Crotés.

Russell Shaffer · « **Reply #5 on:** March 13, 2006, 07:14:59 AM »

I did some looking, and 475 degrees F for one hour was recommended. Do not cool the piston, just leave it for a day. I would assume one could remove it from the oven, just don't put it in water to cool. If it is worn out, you cannot possibly damage it, and if it works, you have a success.

Bill Little · « **Reply #6 on:** March 13, 2006, 07:28:23 PM »

Manuel,

I have "cooked" several iron pistons with some success.All gave me better compression after it was done, and coupled with high castor (29%) content fuel would run quite respectfully. Never like a "new" engine, though. Brian's P/S set up will do that and more.

Like was posted, 475*-500* for about an hour. Cut off the oven and leave it to cool. After it is cool enough to hold you can set it on the bench and put it back together the next day (or at least a few hours later).

Joey Mathison 9806 · « **Reply #7 on:** March 13, 2006, 08:00:20 PM »

if the piston is trash and you have nothing to loose try a copper tubing cutter cut a groove as high as you can on the piston this will get you some more runs on a junker.

Louis Rankin · « **Reply #8 on:** March 13, 2006, 11:00:38 PM »

Yes, cutting or scoring a groove is a very good way to restore compression. I did this on old Torp 19. Just a very slight groove is all you need, and you may need to lap that just a bit.

Bill Little · « **Reply #9 on:** March 14, 2006, 06:24:19 AM »

Yep, "Knurling" a piston works, too!

Tom Perry · « **Reply #10 on:** March 14, 2006, 10:47:10 AM »

Quote from: Joey Mathison 600980 on March 13, 2006, 08:00:20 PM

if the piston is trash and you have nothing to loose try a copper tubing cutter cut a groove as high as you can on the piston this will get you some more runs on a junker.

Try to get it as high on the piston as possible. Note it is possible to lose power from a worn con rod. Leonard sells these on SSW.

Manuel Cortes · « **Reply #11 on:** March 15, 2006, 12:58:18 PM »

Thanks again for your help, friends.

I promise all you to relate my experiences after "cooking" my piston.

Regards form Spain.

Manuel Cortes · « **Reply #12 on:** December 16, 2006, 09:45:10 AM »

Hello all.
After "cooking the piston" in my OS, it has gained apreciable compression, not great but usable.

Ill try it flying as soon as I have a suitable plane for it. Thanks all for your help!!!!!

Regards from Spain.

RandySmith · « **Reply #13 on:** December 17, 2006, 09:29:11 AM »

Quote from: Manuel Cortes on December 16, 2006, 09:45:10 AM

Hello all.
After "cooking the piston" in my OS, it has gained apreciable compression, not great but usable.
Ill try it flying as soon as I have a suitable plane for it. Thanks all for your help!!!!!
Regards from Spain.

Hi Manuel

One thing you need to check is the piston wrist pin holes, They are very very bad to wear out quickly on these engines, if yours are sloppy and worn, it will not matter what you do with knurling ( which tends kill the piston pin holes) or cooking.
I have tried cooking many of them with never a success. The 35S pistons have almost no growth in them new, and you will find most all of them will not grow after being run for a while, you may get a skin baked on them from residue, but I don't think you will have much luck with the baking trick on an OS 35S
As others have said here ,The best thing you could do is try to find another, or get a lapped ne w set from Brian Gardner.
The only other real option is to get someone to chrome the sleeve for you and fit the piston to it
Regards
Randy

Bob Reeves · « **Reply #14 on:** December 17, 2006, 12:02:13 PM »

By the time you pay for getting it all fixed up you will probably be close to the price of a Brodak 40. The B-40 is a drop in replacement using modern materials with more power. I believe they are on backorder at the moment but should have another batch in shortly.

Manuel Cortes · « **Reply #15 on:** December 17, 2006, 12:21:47 PM »

Thanks very much for that appreciable info, will have on mind.
Regards.

Martin Quartim · « **Reply #16 on:** December 17, 2006, 05:09:48 PM »

Quote from: RandySmith on December 17, 2006, 09:29:11 AM

Hi Manuel

One thing you need to check is the piston wrist pin holes, They are very very bad to wear out quickly on these engines, if yours are sloppy and worn, it will not matter what you do with knurling ( which tends kill the piston pin holes) or cooking.
I have tried cooking many of them with never a success. The 35S pistons have almost no growth in them new, and you will find most all of them will not grow after being run for a while, you may get a skin baked on them from residue, but I don't think you will have much luck with the baking trick on an OS 35S
As others have said here ,The best thing you could do is try to find another, or get a lapped ne w set from Brian Gardner.
The only other real option is to get someone to chrome the sleeve for you and fit the piston to it
Regards
Randy

Hi Randy,

How much does it cost to have a liner chromed and fit to the piston?

I got a Enya 45 6002 with some deep scratches on the liner and wondering if it would be worth it to fix it.

thanks,

Martin

Author Topic: Tired OS MAX 35S (Read 2805 times)

Manuel Cortes

Tired OS MAX 35S

Andrew Hathaway

Re: Tired OS MAX 35S

ash

Re: Tired OS MAX 35S

Garf

Re: Tired OS MAX 35S

Manuel Cortes

Re: Tired OS MAX 35S

Russell Shaffer

Re: Tired OS MAX 35S

Bill Little

Re: Tired OS MAX 35S

Joey Mathison 9806

Re: Tired OS MAX 35S

Louis Rankin

Re: Tired OS MAX 35S

Bill Little

Re: Tired OS MAX 35S

Tom Perry

Re: Tired OS MAX 35S

Manuel Cortes

Re: Tired OS MAX 35S

Manuel Cortes

Re: Tired OS MAX 35S

RandySmith

Re: Tired OS MAX 35S

Bob Reeves

Re: Tired OS MAX 35S

Manuel Cortes

Re: Tired OS MAX 35S

Martin Quartim

Re: Tired OS MAX 35S