Thermal contraction of aluminum. Stuck Vintage Cadillac Alum. Distributor in Iron Block 1

[cadchris]

Gentleman,

I am trying to assist the vintage Cadillac community that has a chronic problem and chose the metallurgy section first of this board and will also post the same in the corrosion section.

Vintage Cadillac's of certain years used cast aluminum distributor housings and most of those are seized and stuck in the iron block distributor bores due to most likely galvanic corrosion.

Many have utilized most of the penetrating oils on the market without success only to end up snapping off the distributor housing utilizing available mechanical means to free the distributor...BFH. I have come up with a few different methods for others to try, and one involves super-chilling the distributor shaft outer housing either with liquid CO2 or 134a Refrigerant Freon in an attempt to thermally contract the aluminum from the iron block bore. There are some penetrating oils on the market that do combine an oil with a spray which claims to super-cool an object to -60F to break the corrosional bond or possible galling between these to metals.

Would cast aluminum contract enough from the cast iron bore to break the corrosion bond at -60F or would the temperature need to be far below that point?

These Cadillac cast iron motors were also know to have a high nickel content.

Can anyone calculate this contraction of aluminum or expansion of the iron?
Are we talking about thousands of an inch or greater?

I also thought about if the distributor could be packed in Dry Ice in an attempt to reach -109F for more thermal contraction of the aluminum.

Would heating the iron block to operating temps of 190F or possibly 225F be enough to expand the iron bore while attempting to super-cool the aluminum distributor housing shaft in a further attempt to break this bond?

In addition to the thermal effects on these metals, my idea would be to apply a twisting motion with a pipe wrench attached to the distributor housing and mechanical impacts with an air hammer into the distributor base in an attempt to create some form of harmonic vibration to further break this bond?

I also suggested continuous application of penetrating oil in hopes it will wick down to the target area.

The following link depicts the subject distributor and apparently, the corrosion occurs below the collar on the 2nd shaft bore alignment ring where it sits in the block bore.
Link

Your thoughts are greatly appreciated an explanation a remedial level!

Thank you,
Regards,
Chris

 

[swall]

I made up some acetone/ATF "mixture" once. They do not mix. Its like oil and water.

 

[1gibson]

Honestly, if it were in my driveway and the penetrating oil route didn't work (PB Blaster is my favorite) I would probably try to clamp my reciprocating tool (not sure of the name, check google images and ignore the sawzalls) to the dist, turn the tool on and pull/wiggle the dist until it broke free, then try normal methods of removal (read: vice grips on dist and pry-bar between block and vice grip jaw.)

 

[ornerynorsk]

Along with the thermal treatment, a small slidehammer would be my tool of choice. Twisting on something like that is asking for trouble.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.