[updated:LAST EDITED ON 27-Dec-02 AT 04:39 PM (EST)]I'm trying to remove the last two pistons from my donor 390 shortblock. Each piston is frozen solid in its cylinder by serious rust. (The crank is already out.) We're using a pretty big hammer and #3 and #4 cylinders are just not budging.

Here's the question: regular Coke, diet coke, or some Pepsi product?

Right now I have Classic Coke in #3 and Diet Coke in #4 as a mini research project, but will switch to something else if that's better. How long should they soak? -- an hour, a day, a week?

This worked well on a Jeep 20 years ago, but its rust wasn't as bad as this, and I can't remember which brand of pop I used.

--Matt


1972 F250 Custom Sport Camper Special 4x2 360 2v C6 3.73
Some day hope to shorten to a 104" wheelbase as part of a Broncification project
My FTE Website -- http://www.clubfte.com/users/mlf72f250/index.html
My Galleries -- https://www.ford-trucks.com/user_gallery/displaygallery.php?userid=1108

 

Hey matt
ive had success with marvel mystery oil or liquid wrench to loosen rusted parts..save the soda for later!
just my .02 worth
GOOD LUCK

 

So Coke has Phosphoric Acid in it. I assume that's what's at work there. You might consider getting straight Phosphoric Acid and skipping the research. You might also want to consider just dissolving the Aluminum pistons with Nitric Acid.

When I disassembled my 292 Y-block I had to scrape the rust out of the cylinder bore above two pistons. I was able to push the pistons down enough to get at the ridge of rust. Once I had scraped and scratched the rust scale off, I used a cylinder hone to smooth things out.

It still took soaking in PB Blaster and pounding from below with a 5 lb. sledge on a 2x4 to get those monkeys out of there.

Good luck.

 

[updated:LAST EDITED ON 27-Dec-02 AT 07:50 PM (EST)]Ben and Paul,
Thanks, I like that thinking! Maybe next time a mix of phosphoric and nitric acid with a MMO chaser would do the trick. ;-)

After almost two hours of soaking the Diet Coke (#4) seemed have a slight advantage, although that one was reported to be slightly looser before the acid treatment. We wound up using a big hammer and a brass drift. Those main saddles are pretty sharp. Yeowch! After two hours of pounding and surprisingly little cursing, #3 piston came out in pieces and #4 came out almost intact except for the hole in the top and miscellaneous dents.

In retrospect, giving it more soak time probably would have made it easier. I'll definitely have to look into the acid + MMO options. I wonder what the big industrial rebuilding folks do?

Anyway, I now have a 390 crank and connecting rods and will proceed.

Thanks again.

--Matt


1972 F250 Custom Sport Camper Special 4x2 360 2v C6 3.73
Some day hope to shorten to a 104" wheelbase as part of a Broncification project
My FTE Website -- http://www.clubfte.com/users/mlf72f250/index.html
My Galleries -- https://www.ford-trucks.com/user_gallery/displaygallery.php?userid=1108

 

Matt
glad to hear you god those badboys out! You arent anywhere near New Jersey are ya? I have an ole 400 that is stuck and its still in the truck and I pretty much have given up hope. I tried the MMO, the pepsi and the liquid wrench PLUS beating on it--all to no avail! I think im gonna need dynamite to break it loose. TO make matters worse, it is the DRIVER real cyliner that is rusty so its kinda hard to get at with the engine in the truck. Wanna come over and work some of yr magic on my truck?
I honestly dont know if its rusted stuck or the idgit that sold it to me tossed a rod and thats what is binding it up (havent dropped the pan yet)---i iced this project truck for now. But hey, If you wanna take a crack at it--a 30 pack of bud is in it for ya
Regards
Ben

 

I've used kerosene and/or diesel with dry ice on a 302 that'd been left out for a year without heads. Moderatly rusty. The pistons practically fell out.