vipervetteguy

1956 car. Since purchasing my wife's car, I've done a massive amount of researching regarding the transmission puking after the car sits for a while. Hers will puke after just a week or so. I understand that there are no real fixes for this situation. If we drive the car very few days, it doesn't spit all over the floor. Here's my question: Any estimates as to how long it needs to run in Drive so that the pump refills the converter? Is this something that should happen in just a minute or two? Right now we usually take the car for a quick 2 mile drive, but sometimes a shorter route would be nice. Yes, I know we could just experiment, but it would be easier if someone could share what they know from their own experience. Thanks.

pinball

The answer to your question is three to four minutes at idle. Now for a few more details. I am not an expert on powerglides, or anything else, but over the last 50 plus years, I have had several powerglide cars. What I do know based on my experience is that the puking out of the dipstick tube did not occur in the old days, but once the cars stopped being daily drivers, the problem surfaced. The problem can be resolved. What happens is a check valve in the valve body does not function properly, which allows fluid from the converter to seep back into the transmission sump. The longer the car sits, the more fluid goes into the sump. Your transmission is now overfilled. That is why you are not having an issue when the car is used regularly, but it will barf after sitting for several days.

FWIW, I bought an unmolested 55 Chevy with a 265/PG several years ago. The car had sat untouched for at least 28 years. Once I got it driveable, without any major engine/trans work, I used it for several months as a daily driver. That powerglide did not leak and never barfed. Conversely, the glide in my 57 Chevy has been leaking and barfing for years. The last time that the transmission projectile vomited all over the garage, it was removed from the car the next day and replaced with a Muncie 4 speed. So, your options are:
1. Pull the trans and have it fixed correctly. IF you can find someone competent to work on a PG, and you can find the parts, and you want to spend money.
2. Leave the trans in. I vented the 57 tailshaft housing to help minimize internal pressure. I also made a crude overflow tank that replaced the dipstick. Unfortunately, it wasn't on on that fateful last start. An overflow system could be fabricated that will eliminate the mess, but will require regularly drainng the overflow and topping off the trans. And most importantly, if you can start the car and keep it below about 800 RPM for 3-4 minutes, it will not barf. Easier said than done, but here is the technical, exhaustively researched formula:
wet sump + RPM= Barfing.

I can see if I can find some legitimate information I have collected over the years in my library, but the above is a short version of my love affair with Powerglides.
Kerry

vipervetteguy

Thanks for that response. Right now we keep the fluid at the bottom of the dipstick and run the car around the block once a week or so. I have a hose from the dipstick tube to a bottle under the car to catch fluid on start ups. (usually a few oz) When the car sits for weeks (on vacations) the trans does leak from the driver's side, too. The car is incredibly original, so a Muncie isn't a consideration.

Scott Marzahl

This may be of interest

"Sonnax Cast Iron Powerglide® Leaks" https://www.sonnax.com/tech_resource...werglide-leaks

boxster99t

My 67 PG pukes too, and I had the transmission rebuilt around 10 years ago when I lost second gear--puked before and after the rebuild and the shop I used was the one that Car Campbell in Plano TX recommended. I just live with it and once in awhile check the transmission fluid and add more.

vipervetteguy

Interesting reading. From my research, the consensus is that the vents and valve just don't really work.

Dan Hampton

Nice article, Scott. It touched all the base problems.

csherman

for the 53 54 55's - i do a couple things - right or wrong
1 - I run them about a 1/2 qt low....
2 - I shut the car off in reverse
Now I am sure these could be old wives tales but seems to work for my customers and I.....

MOXIE62

I've read where you are not suppose to idel the engine while power glide is in park. Not sure why.

scopeli

Old question and old answer. Torque converter is leaking back into the main body and when fully leaked down, level can get to the highest point of the tail shaft housing. A vent would ideally be drilled into the top of the main housing as it is in later powerglides. With the transmission already installed, you are left with drilling a hole into the highest point on the tailshaft and screwing in a vent tube. This should be enough to prevent burping, but as an extra step a hose can be connected to the vent tube and run to near the top of the transmission filler tube where you can attach the vent hose with a wire tie.

scopeli

What type of research have you done? I have actually installed the vent on the tailshaft after the transmission was installed and it has always prevented the powerglide from burbing.. Problem with rebuilding powerglides such as the one on a 55 corvette is that unless you can locate a valve body 4.216 #3719234, casting #3719233 in like new shape, you will have fluid bypassing at the point where the worn valve body and oil ring on the small input shaft from the converter mate. Second problem point is where the two ring on the valve body mate with the clutch drum, but the rings and clutch drum are easier to locate. Third problem area also has to deal with the valve body and that is the converter pressure regulating valve, 4.216, part #3713696, that is located inside the valve body.

vipervetteguy

Can you please provide to me the parts info necessary to install tail shaft vent? It certainly sounds like the vent is worth a try. Thanks.

vipervetteguy

Vent question: Why doesn't fluid burp out the vent on the tailshaft?

scopeli

Go back to Dan Hampton's post and view the 90 degree fitting on the tailshaft. Google "quarter inch transmission vent". The last vent I did is connected from the fitting on the tailshaft to the back side of my sparkplug wire guide where the "quarter inch trans vent" is attached with a wire tie. It is so well hidden that it took me quite a while to figure where I had placed the vent!