Rusted V12

[DSpringer]

I've got a replacement V12 for the 49 Merc V8 my 41 Zephyr has been running, but the pistons are solidly rusted in place. Is the Coke solution a myth? Is there a better way to break the pistons loose short of a sledge hammer and lots of WD40?

Dave

[Guest imported_V12Bill]

Try ATF, or diesel fuel , or a 50% mixture of ATF and acetone. Let sit for a few days and any of the above will loosen the grip of rust. Some persuasion may be required.Don't use a BFH, work the crankshaft back and forth by prying a screwdriver in the starter teeth.

[peecher]

Dave, you may find it a bit easier to loosen those pistons if you'll first remove the crankshaft. You can then gain access to both sides of the pistons and work on them individually. I have found that liberal amounts of Kroil to be a good penetrant but "jarring' the piston back and forth seems to help. You may indeed end up having to use a BFM to get them out. Below is a worst case scenario, I took weeks of "massaging" to finally get this critter apart. Good luck

[DavidAU]

The 50% ATF & acetone is the best rust breaker. Just let it soak in. If everything fails and the pistons will not move do not hit them with a BFH, you are liable to crack the cylinder bores. The best method is to put a big hole saw thru the middle of them, cut them down the sides a few times with a hacksaw blade and then break them in.

David

[DSpringer]

I figured you guys would be a great help. I'll start with Kroil or ATF/acetone, working the crankshaft, pulling the crankshaft, and finally my sawsall, and let you know how it goes.