Warbird Information Exchange

Pat, once the cylinder bank is removed...how difficult would it be to remove
an individual cylinder liner and R&R? Looking at the following photo, it doesn't look that
much of a hassle...but of course I haven't a clue from personal experience...
www.missthriftway.com/Photos/engine/11-14%2001.jpg

AND...thanks a bunch for the Allison Miss Thriftway link...I wasted a "bunch-o-yesterday"
looking for that website. I knew of a few on Merlin, but not Allison.

EDIT-to repair link

_________________
He bowls overhand...He is the most interesting man in the world.
"In Peace Japan Breeds War", Eckstein, Harper and Bros., 3rd ed. 1943(1927, 1928,1942)
"Leave it to ol' Slim. I got ideas...and they're all vile, baby." South Dakota Slim
"Ahh..."The Deuce", 28,000 pounds of motherly love." quote from some Mojave Grunt
DBF

Airnutz-

To be honest with you, I can't tell you how difficult it would be to R&R a cylinder liner; I've never laid a wrench on an Allison; most of my experience has been with heavy commercial turbine aircraft, with the exception of working on a B-17G infrequently in the past.

According to "Vee's for Victory" (published by Schiffer), a GREAT book on the subject, the liners were installed with an interference shrink fit. The compression nuts on each sleeve were torqued to 2,100 pound-feet. I doubt they could be easily removed without special tooling.

-Pat

Ahhh, thanks Pat. After my post I continued looking at their photos and found the
answer to my question. In the photo I linked you to, it appeared as if they
were individual cylinder/cooling jacket assemblies bolted to the cylinder head
and then lowered down onto the engine block. Such is not the case inthis photo looking above the wasted piston/liner combo..
www.missthriftway.com/Photos/engine/OOPS.jpg

It wasn't really clear(to me), in Bill G's original explanation, but your detail from the book
and the photo cleared up the answer. Not an easy field fix.

It's been ages since I've seen a blow-up schematic of the Allison and this has
been entertaining and informative. Thanks all!!!

The W-24 from "Yancy Too" was a nice surprise...I'd like to see more of that
project.

Thanks again Pat!

_________________
He bowls overhand...He is the most interesting man in the world.
"In Peace Japan Breeds War", Eckstein, Harper and Bros., 3rd ed. 1943(1927, 1928,1942)
"Leave it to ol' Slim. I got ideas...and they're all vile, baby." South Dakota Slim
"Ahh..."The Deuce", 28,000 pounds of motherly love." quote from some Mojave Grunt
DBF

Please look under the topic of " Rudy Frasca" if you would like to see another view on modern service of these type engines. Sorry I put it in the wrong place.

_________________
Bill Greenwood
Spitfire N308WK

The cracks can be caused by many things.
Defects in the material, such as pockets and or inclusions (debris). Improper machining, assembly, heat stress, overloading just to mention some. The part could have been cracked before it was installed and just not caught. People drop things all the time during the manufacturing processes, as do the mechanics and technicians doing the assembly work.
That is a big problem these days especially I think, too much of the thats good enough attitude or toss it around stuff as well. I have worked with many like that. I'm amazed there aren't more problems.

Yes, you have to pull a cylinder bank in order to change a cylinder liner. With the right tools it isn't difficult. Without the right tools, it is almost impossible. The cylinder liners are held in with a thin nut torqued to 2,200 foot-pounds and that is not a misprint.

I worked with Joe Yancey for more than 1 1/2 years on Allisons at his shop in Rialto, CA. We did all four engines for Galcier Girl (well, Joe did and I helped a bit on a couple ... the "we" is Yancey Enterprises, consisting of Joe and Pat Yancey). Rod Lewis has 4 Allisons for his P-38, 2 in the plane and 2 spares. All 4 come with Joe Yancey overhauls. 2 are the original engines from under the ice.

Most of the tooling does not exist anymore, but really isn't all that difficult to make if you have a lathe and an end mill. Joe has several of each and makes his own specialized tooling. Once you get the cylinder bank off, you put it in a special unit made to torque / untorque the cylinder nuts. First, you have to make the socket.

Not too difficult if you actually need to do it. The special mount has a torque multiplier on it (11 : 1 torque multiplier) . That allows you to torque it with a 200-pound pull using a 1-inch drive unit and a 5-foot breaker bar (and sometimes an extension as you get tired). Once the nut is off, you have to heat the cylinder block to 500° F, then throw ice into the cylinder to cool the liner, install a special hydraulic puller that grabs the liner and uses a small hydraulic jack to get it off. Again, not too difficult if that is how you make a living.

Then you hone the liner (Joe uses a Sunnen Cylinder Hone) unless it is erroded too far or cracked. Most cracked liners are due to uninformed people running the JRS (John Sanders mod) piston mod whereby they remove the bottom oil ring, cut the third compression ring wider and use it for the oil ring, eliminating the bottom ring. Therein lies the issue. Without the bottom ring, the piston is free to slap about, especially around idle, and the result is a cracked liner at about 250 - 350 hours of operation.

The solution is simple ... run stock piston configuration and you can get over 1,000 hours with no cracks in normal aviation use ... not in racing use.

Anyway, to reinstall the liner after it is honed you put the liner in the freezer and heat the cylinder block to 500° F. Then drop the liner in. It just drops right in and gets an interference fit quickly as it cools. The next trick is to use a special jig to make the liner stay round while being torqued to 2,200 foot-pounds. Sometimes you have to play with that one a few times to get it right. After doing a few, the re-tries become less and less as you gain experience.

Sounds very complicated and IS if you don't think it out and have the tools ... but, if you DO, it is simply work, not impossible.

Need a cracked Allison cylinder liner changed? Contact Joe Yancey at Yancey Enterprises, Rialto, CA. He can do it easily and rather quickly if need be. Send him the cylinder bank (or take it there yourself) and he can bring it up to airworthy condition, assuming the bank isn't cracked or too erroded or otherwise damaged beyond use.

If it IS, you can get a serviceable bank from Joe ... or an entire overhauled engine as the situation warrants. He has quite a few ready for overhaul. Good luck!

If you are smart, you'll have him do the valve seats and valves, too, at the same time. That way the bank is ready for use on a running engine when you get it back. He can make your "E" engine into an "F" or vice versa, has "G" engines rready for overhaul, and even has a couple of auxiliary stage superchargers ready for overhaul and sale if you want to tackle Reno with an Allison.

_________________
There are two kind of aircraft, fighters and targets

Wow...that was a pretty awesome and informative post. Thank you. And, here I am thinking that overhauling the cylinder head off of a 1275cc motor from a 1969 Austin Healey Sprite is going to be a complex operation.