Warbird Information Exchange

Hi there.

I'm hoping someone with Merlin overhaul experience might be able to help me out a little with cyinder/head removal techniques?

Basically I have an engine which has been sitting for 60 years and I am up to the stage of pulling off the cylinder banks. Everything is pretty much seized over time, so I am interested in any ideas that might help? I have of course been regularly spraying the whole lot in penetrene for about the last 6 months!

I am currently thinking of 2 options -

1) hydraulic removal by injecting grease with a high pressure gun into 2 opposed cylinder chambers (ensuring valves are closed & the other spark plug hole is blanked).

2) mechanically jacking them off using a steel plate with high tensile bolts against the cam gear studs/cylinder studs.

Obviously my main concern is getting the banks off without damage, so if anyone has any experience or can think of any other options regarding bank removal of an engine thats been sitting for 60 years, I'd appreciate the advice.

Thanks!

jason

I wouldn´t be trying option one. If it does come apart, I would think it may be liable to do so with a big bang!

What about chaining the bank to the roof and then lowering the engine, so its weight trys to pull them apart? Given some more oil and a little time, who knows? It would seem to be a bit more gentle than either of your methods.

Just an idea.

JD

Is this stuff available where you are? I’ve found it to really work in these situations. Try a little heat, too.

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Do you have the screw jacks designed for the task? I think that they push down on the studs. You don't normally just lift the head and bank assembly off the crankcase, even on an airworthy engine.

Hi Jason,

I've done a couple Merlin and Grifon bank R&R's over the years. I would suggest you proceed with caution. Some of the things you are thinking about trying and one of the suggestions made in this thread could end up in severe collateral damage to otherwise serviceable parts.

First off I would suggest you go no further until you have a proper set of head/bank jacks and read up on the proper removal procedure if you have not yet done so. Without jacks you're chances of success are nearly nil and if you should happen to get the banks off without them, you will more than likely damage studs and possibly the heads and jackets as well. As Brandon indicated, you don't just lift a set of banks off the lower case with "Armstrong": number one, they are too heavy for that and number two; they MUST come up evenly and slowly. If, with the proper jacks and procedure you still cannot get the assemblies off, you may have to resort to removing the heads from the cylinder banks first, if you have a series engine where they are separate subassemblies. Doing so will give you access to the piston tops so you can take further action on them individually such as "Kroil" penetrant and mild heat. If there is still no joy, you may have to resort to working from the bottom up removing the "Pan", unbolting the rods from the crank and taking the piston/rod assemblies with the banks. After you get the banks off, each individual piston/rod assembly that is seized to the liner can be removed from the jacket/block worked on individually. If it comes to this, be VERY careful not to nick or ding the rods on any of their surfaces, the crank journals and any other machined surface. If you do things correctly you should not have to destroy anything and it's possible to end up with a lot of valuable components that could fly again. Do it wrong or carelessly and you could end up with $30,000 worth of JUNK. Time and patience!

Hopefully Glenn Wegman will see this thread and offer some of his valuable insight.

John Beyl
CC CAF P-51C

I don't have the screw jacks that the manual refers to, though I have been unsuccessfully searching for at least a detailed photo so that I can have some made.

When I was discussing this problem a couple of years ago with an old ex RAAF engineer, he mentioned that the Rolls Royce tool used to bear against the top of the cylinder studs, though I wasn't sure what it attached to on the cylinder head? (was it small lands on the cylinder head base??)

Anyway... if anyone has a photo of the tool, I'd very much like to see it?

I appreciate the input.... thanks!

Jason

Talk to Col Pay at Scone - he will steer you in the right direction and may have the tools - he certainly knows his way around these things

I agree with others it would be really sad to bugger up a good set of parts - most engines are "stuck" at first and eventually come good once you have the "knowledge" from the experts

John

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Dave, try this site for a photo of the tool in question, as well as others in
the For Sale/Wanted Section...
http://members.lycos.co.uk/pwgrieve

Peter relates that he has drawings of some of his tools. But of course, If
you can borrow the proper tool from Col. Pay you would have the
additional benefit of a tutorial.

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The two on the right:



http://members.lycos.co.uk/pwgrieve/hobbies.html

A grease gun is the go,done it several times.
Modify one spark plug to take a grease nipple and borrow an air operated gun.Cos they take some filling,if it leaks thru a valve just tap it with a hammer til it seats.
That way you don't damage anything,although we did split a cylinder sleeve in an Allison once.
And you know the thing isn't going to fly off and hit you in the head.
It will creak and moan a bit,but it's just talking to you.
(DON'T USE AIR or you might get a face full of bank)

Sounds like some wimenns I know..they're so demanding!!!!

But seriously, good technique Mick..I'd forgotten that one.

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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

Rather than using a penetrant, which isn't a bad thing to do, put the exhaust side plugs in and FILL each cylinder as you can from the intake side with jet fuel and let it soak. If you have access to a turning tool which fits a 50 spline prop shaft (assuming nosecase is still on) see if you work the engine back and forth to get it free. I can tell you that if it is packed up and the cylinders are doing it, there is probably already a fair amount of damage there from just plain rusting. Be careful but persuasive. You probably will need some type of bank jacks to get it free, but try the jet fuel for awhile and see if that helps, but fill them full.

Sparrow

HI A LOT OF GOOD IDEAS BUT START BY FILLING THE CYLINDERS WITH MARVELOUS MYSTERY OIL LET IT SIT FOR A FEW DAYS.IF THAT BRINGS NO RESULTS THEN THE GREASE GUN TRICK WILL DO THE JOB!REMOVE THE CAM SHAFTS THIS WILL CLOSE ALL THE VAVES THAT ARE NOT STUCK OPEN.PUT A MODIFIED SPARK PLUG/GREASE ZERK IN EACH CYLINDER AND START PUMPING.AS MENTIONED IT WILL NOT FLY OFF AND KILL YOU BUT WILL MOVE A LITTLE BIT WITH EACH PUMP.I DONT THINK THE SCREW JACKS WOULD WORK WITH OUT DAMAGE TO THE ENGINE OR THE JACKS.THANKS MIKE

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No disrespect to the previous poster, however having removed and seperated many, many cylinder banks-- the bank jacks are the best way to remove the banks from the engine. The marvel mystery oil will do as well as the jet fuel so whatever works. The best way is to see if you can get the engine to turn over before you try to pull the banks. If you get it freely moving then it's not a problem.

Sparrow

HI I AGREE,I WAS ASUMING THAT IT IS FROZE UP .THE GREASE TRICK IS A LAST RESORT BUT HAS WORKED WELL MANY TIMES, IT ALSO WORKS ON FROZEN OLEO STRUTS .THANKS MIKE

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IF YOU CAN FIND IT WE CAN FIX IT