Power glide re-seal vs other

[57barnwagon]

Is the power glide prone to leaks and is it worth the time vs changing to another version? It runs well as long as you top off the fluid. But it leaks out when parked.

[carls 56 (RIP 11/24/2021)]

topping off is probably your problem. its called "burping or puking'" and is common to PG. i have heard that not filling can help.

[57barnwagon]

it will slip if I do not

[567chevys]

Here this Might help you

This is also on this site

This is from a company that makes excellent upgrade parts and problem solutions for automatic transmissions.

Here is a link to a technical discussion about the Cast Iron Powerglide leaking issue.

https://www.sonnax.com/tech_resource...werglide-leaks



Here is their explanation of the cause, and the proper fix for the pre-’58 Cast Iron Powerglide:

Before 1958, the only vent for the transmission was the opening at the top of the fill tube. The dipstick did not have a positive seal, and was designed to allow air to enter and exit the transmission.

The Hydra-matic™ transmission of that day had a similar dipstick, but it entered the transmission at the top of the case and vented the entire main case and extension housing cavity equally. Since all of the cavities of the Hydro-matic were well vented, leaks were not an issue. By comparison, on the C.I Powerglide, the dipstick tube enters the case at a lower level. This means that - when the fluid is at its proper level - this area is isolated from the rest of the main case cavity. When all of the area inside a transmission case is not vented equally, pockets of pressure are allowed to build up. The vented area of the main transmission case and the extension housing are connected by an orifice in the 11 O'clock position in the rear pump.

This orifice was restricted by a small pin. Veteran C.I. Powerglide rebuilders learned the hard way that leaving the pin out of the orifice in the rear pump would cause the transmission to burp oil out of the dipstick. Before the vent was added to the main case in 1958, this burping action was the only way that a pressure build up could be exhausted from the main case. This pressure build-up also explains the numerous stubborn leaks.

To retrofit a vent to the earlier transmissions, a 90° brass fitting was added to the extension housing. A length of fuel line hose with a plastic vent (from a 350 transmission) was attached to the fitting. The end of the hose with the vent was then attached near the top of the dipstick tube.

Unfortunately, this root cause analysis was started more than 50 years too late for this problem, but hopefully it will help with the way we approach future ones.

Hope this helps!

Harrel Lamkin