My worst nightmare came true. My H9 P-51 lays in pieces on the bench in my shop. Now, to say that it it hit hard is an understatement, and I won't go into it as I have posted pics on crash thread. My question is this...today I'm going to tear motor down,(it's an OS 46AX) clean, visually check, pull apart, put back together, yadda yadda yadda. Since this is my first major ground incident, I don't have a lot of knowledge on this. The only thing I see wrong is that when it hit, the muffler contacted first and sheared off(told ya it hit hard ) It broke the side of the jug that the muffler bolt run through, not all the way up, only about the bottom(muffler side)third.(see pic) The sleeve still has plenty of metal left to hold muffler bolt in place, but will this have any adverse effects? I haven't bench ran motor yet, but am planning to this weekend. If nothing is twisted or bent and it runs, I'm planning on putting it on an old H9 Xtra easy trainer for shakedown. Any help or advice on this would be greatly appreciated, because I don't have a lot of club contact in winter months(very small club). This crash has yeilded a wealth of knowledge, and I need all of that I can get.

Well, while you are tearing it down, clean it up. You can fill the side of the jug with JB Weld and drill it out. Otherwise, it is just a beauty thing, you have enough metal left to hold a muffler on. If the muffler is torn up, get you a Tower Muffler -- they are inexpensive -- about $12 or $13 and four dollars shipping cost. The Tower Muffler will give you 5 or 6 hundred more RPM.

If the crankshaft is not bent, there probably is no reason to tear down the engine. But if you want to do that, make sure you mark the connecting rod so that it goes back in like it came out. I would recommend when you have the back plate off, to wash out the inside of the engine with alcohol, flush it well and use a "Sharpie" pen to mark the connecting rod. You will have to take the sleeve out to get the piston out. Should just slide out, it not use a piece of wood to push it out from the inside of the crankcase (part of the sleeve sticks down into the case). Don't use metal as it may distort the sleeve. There is usually a pin on top of the jug to align the sleeve with. When you get the head off, clean the top of the piston and mark it also so that it goes back in the way it came out.

I would wash everything off under soap and water, clean well and make sure no soap residue remains, use after run oil to reassemble. I use Dextron Transmission fluid - have seen mechanics rebuild car engines use the same stuff.

Depending on how old the engine is, replace the bearings while you got it all torn apart. Boca Bearings and RCbearings are good sources of "how to do that" job. They are also good sources for bearings -- shop around, some dealers are less expensive. You can even get them at bearing houses in bigger towns. There are lots of threads on how to replace bearings on RCUniverse.

Enjoy the job, not hard to do. Just pay attention and take it easy.

Cheers,

Chip

Chip--Thanks for taking the time to help--great advice. Although this question belongs in a seperate post, you said the Tower muffler will give me 5-600 more revs. Is this over the stock muffler?

Yeah, get the tower muffler. They are great and will really wake up your engine from it`s sleep. I use one on my 52 xls and it hauls butt

If the engine hit nose first in hard dirt you need to change the bearings. I have tried to avoid changine bearings only to later have to pull the engine and change them anyway. Looking at the motor I would say it is time to change bearings anyway. If you can't get them cheap you might as well toss the engine and get you a Supet Tiger 51.

Going by where it broke, looks like you can get a new muffler on their using some gaskets. Going down that road. Many never use gaskets at all. With your mess, you may want too. I never use the ones that come with engines. I go to Pepboys and purchase really thin gasket material. Usually inthe area where they have all the tubes of RTV, Thread locker and muffler glue crap and JB weld. I cut it to fit and works fine.

IMO, if you have already made sure that no dirt / etc. got inside and the engine turns over smoothly (no roughness in the bearings ) then just bolt the muffler on and fly it...the broken part is just an asthetic thing, but a little gasket goop would help insure a good / better seal.

The Tower muffler is awesome, especially if you let the engine rev up into it's "sweet spot"...
Put an APC 12 X 4 on it for your XE and you'll be surprised

Thanks all for the insight. Tore it down and cleaned it up today. Found some grass and a little dirt on top of cylinder, from separation of muffler then half gainer with a twist through the weeds[X(].Bolted up to old trainer and ran two tanks of fuel through on the ground then two more in the air. Ran smooth with no noticeable vibration or power loss. I used a muffler off of an old MDS 40 (that refused to stay lit) and seemed to work OK. Not what I'll stay with, but seemed to do ok. Thanks all for taking the time to help.