Repair and Replacement Information For Your Imperial's Transmission Gasket


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Question from Brooks (1961):

Awhile back I changed the fluid on my '61, and I wondered if anyone else had run across this. I have always used silicone to seal the cork gaskets, as otherwise they tend to shrink over time, and start leaking.

I noticed the directions that came with the new cork gasket said to coat both sides of the gasket with grease. As in chassis grease. I thought "That's just about the stupidest thing I ever heard of", but thought "what they hey, let's see what happens. These people probably know more about this than I do."

Well, I am here to tell you that it STILL isn't leaking....much to my amazement. Has anybody else ever tried this?


From Rich:

Hey, you are absolutely right ! I used to use silicone on my trans. pan gaskets also, more to hold 'em in place than to seal anything. I then went through an Automotive Technical School (Vale Tech. in Blairsville PA), & General Motors Training Center ( in Monroeville, PA). At both places I was told to never put silicone on an automotive transmission. Apparently, the detergents in the Trans. fluid dissolve the silicone over time, & you will have bits of silicone floating around clogging up the filter or possibly getting stuck in something. Always use that grease. Also, I have learned that it is a big help to but the gasket & filter kit a couple of days before you plan to do the job. Then you can lay the gasket out flat somewhere. This helps to keep the gasket in place. Otherwise , you are fighting the gasket trying to return to its " rolled up" condition of how it was jammed into the little box.

From Steve:

I have always used a thin coat of Aviation Form-A-Gasket on the trans-pan and on the mating surface on the tranny. The Form-A-Gasket is a tar-like substance and comes in a small plastic bottle with a brush. It is available in all part stores.

I'll clean the surfaces thoroughly and straighten out any dimples that over-tightened bolts made...then apply a thin coat of the gasket material, and let it sit until it gets "tacky". Then, I'll place the gasket on the pan, making sure all of the holes line up, then I'll turn the pan (that now has the gasket loosely attached) upside-down...onto a flat surface and set a weight or brick on the pan.

After an hour or so, remove the weight and install the pan. The gasket will be firmly held in place on the pan as you install the pan on the tranny. No more fiddling with getting the holes lined up. I always brush a little on the tranny about 1/2 hour before...and wait until it gets tacky too.

Note: Do not let this stuff spill in your toolbox! Been there, done that. Carburetor cleaner helps during clean-up.

Question from Tim (1967):

My '67 has developed a transmission fluid leak. It's not a steady stream, but three days in the garage is enough to produce a "pool of blood" on the floor under the front of the car.

My mechanic tells me I should bring him a "pan gasket" to fix it. But is "a pan gasket for a 1967 Imperial" enough information for the nice person at the parts store to know what I need? I don't know nothin' 'bout fixin' no transmissions, and their computer systems don't typically go back as far as '67.

I see the following transmission gaskets listed at, all made by Pioneer Products: Trans. Gasket: front pump: A904 $2.59 Trans. Gasket: front pump: A727 $0.99 Trans. Gasket: extended housing (incl. A727) (incl. A904) $0.99

Is one of those what I need? They sure are cheap!


From Rick:

My guess is the shifting linkage seal needs replacing.  The fluid level goes up as it sits and can reach the seal level and if the seal is worn or just plain old, they can start to seep fluid.  It's not a hard fix, just drop the transmission pan, disconnect the linkage, drop the valve body.  The seal is in the shaft hole - knock it up and out.  The new seal is in the hole and down, reassemble with new filter as long as you're in takes 1 to 2 hrs for all of it.

From John:

I recently read an article on sealing up 727s and they suggested using a new pan gasket P/N 2464324AC. It is a rubber, metal cored gasket with torque limiters. I bought one at the Chrysler dealer for $16 and am going to replace the cork gasket this weekend. I will report back if it eliminates the puddle under the transmission.

This page last updated February 11, 2004.  Send us your feedback, and come join the Imperial Mailing List - Online Car Club