The Stovebolt Site Forums The Shop Area Engine Shop Tranny leak

Hi all,
Please refer to the tranny photo at the end of my little metal pointer I have a small crack in my tranny. Is there any sealant I can use to stop the leak?

Thank you!

Jon

UnklRod asks, "Is there any sealant I can use to stop the leak?"

This is not good. First question is, "What caused this crack?"

Looks to be where the end of a cluster gear shaft resides or an idler gear group shaft. Cannot remember which for those old three speeds. Either way, this crack might be more extensive than appears; micro fracture hard to see or covered with paint.

If this trans has been rebuilt after the crack fact, probably not a problem but your case is weaker in that area. Most likely cause was high stress or blowing up inside. Really should replace that case part of your transmission.

These cast iron cases can be brazed but there is a need to drain the oil to do this and grind down to clean metal. Cannot have oil under a braze repair and more oil will weep out during heating. This is problematic.

Quickest fix is arc welding, but also requires clean metal and as little oil present as possible. Arc welding will burn away any weeping oil.

As you know, welding will mess up the paint. Brazing causes an issue with your tailshaft housing gasket; lot of heat is required for brazing. Arc welding is a better choice but more messy, requires some grinding and cleaning.

A "maybe" cure is fiberglass epoxy resin like from Home Depot. This also requires clean shiny metal and no oil present. I would grind this down to good clean metal, a bit scratched up for adhesion, clean with lacquer thinner, cut out a matching patch of fiberglass cloth, mix my resin, wipe the crack area with acetone, then epoxy this fiberglass patch over the crack. Very important to clean with acetone just seconds before repairing.

A two inch by two inch fiberglass patch, or thereabouts, would probably hold and stop this leak. Might leak a little right at the crack but under the patch. While the rest of the patch strongly adheres, chances are good no oil will escape from under this patch. Applying several coats of resin with sanding between would be a very good idea. Time consuming but worth the effort. You can feather the edges, never will notice a patch is there.

Prime and paint, ready for a car show.

Give the fiberglass / resin method a shot first, then consider brazing or arc welding. For all methods, clean shiny base metal is a must; no paint residue.

Be gentle on this trans, I know you will. You have a weak area there, a delicate area. Probably will be OK but don't push this.

Billyray

Hi Billyray,
Thank you very much for the info. I had the tranny rebuilt about a year ago. I have not tried the tranny out yet because of the resto I am doing. I filled it the other day with fluid to see how it would go and that is when I saw the leak. Now, the guy who rebuit it never said anything to me.
I will try your ideas to fix it and see how it goes. Thank you for the info!

Jon

Jon,
Are you sure it is a crack? It is in the location of the reverse idler lock pin. They have a tendency to leak. I would clean off the paint around it and make the determination. If it is seeping around the pin, a little JB weld should do the trick.
Fred

Try JB Weld, but get it good and clean first.

The picture looks more like a casting imperfection than a crack. There is no reason for the housing to crack in that particular spot, and an actual crack would not be as pronounced. I would clean everything up and see where the leak is actually coming from. If it is indeed a crack, I would find another housing. There plenty of them around.

Jon - I'll 3rd the JBWeld plan, cleaned well with solvent and power wire wheel [oil drained] - definitely skip the fiberglas, no question, it won't hold long term unless you use special resin meant for application to metal

Bill

Hey guys,
Thank you for the help, I would have thought the shop who rebuilt it a year ago would have brought it to my attention. Sorry about the poor picture. Wanted to give you all an idea where the leak was. I will see if I can get a better photo tonight. I am all about the JB. Once truck is running I will see how things go.

Thank you again!

Jon

Spoke with the shop that rebuilt the tranny. Showed him the photos. He said it should not be a problem. Suggested the JB weld and if there is a problem bring the truck in.

Thanks all,

Jon