1980 TH350 auto...What drain plug?
Thread Starter
Pro
Joined: Oct 2006
Posts: 545
Likes: 2
From: Peoplez Republik (communist portland) Orygun
1980 TH350 auto...What drain plug?
My automatic TH350 trans-pan is leaky. I wanted to drain the transmission & put on a new gasket. The manual shows some TH350's having a drain plug and a filter of some sort...Well, I don't think my tranny has a drain plug.
Is it possible that not all TH350's have the tranny drain plug?
If so, to drain the tranny, is it advisable to simply unscrew the pan and drain it that way? How much fluid is going to come out?
Yes, I can rebuild an engine. But when it comes to carburators & auto transissions, I stay the H3ll away in fear
any tips?
AP
Is it possible that not all TH350's have the tranny drain plug?
If so, to drain the tranny, is it advisable to simply unscrew the pan and drain it that way? How much fluid is going to come out?
Yes, I can rebuild an engine. But when it comes to carburators & auto transissions, I stay the H3ll away in fear
any tips?
AP
Burning Brakes
Joined: Nov 2005
Posts: 1,143
Likes: 0
From: Leander Texas
I have never seen a th350 tranny with a drain plug. I've always just losened the pan bolts, and let the fluid drain that way.
You'll get about 5-6 quarts to drain out.
It is best to leave some of the pan bolts in until it stops draining. then remove the rest. Warning there will still be about 1 quart still in the pan that youm will wear.
You'll get about 5-6 quarts to drain out.
It is best to leave some of the pan bolts in until it stops draining. then remove the rest. Warning there will still be about 1 quart still in the pan that youm will wear.
Race Director
Joined: Feb 2004
Posts: 12,518
Likes: 19
My automatic TH350 trans-pan is leaky. I wanted to drain the transmission & put on a new gasket. The manual shows some TH350's having a drain plug and a filter of some sort...Well, I don't think my tranny has a drain plug.
Is it possible that not all TH350's have the tranny drain plug?
If so, to drain the tranny, is it advisable to simply unscrew the pan and drain it that way? How much fluid is going to come out?
Yes, I can rebuild an engine. But when it comes to carburators & auto transissions, I stay the H3ll away in fear
any tips?
AP
Is it possible that not all TH350's have the tranny drain plug?
If so, to drain the tranny, is it advisable to simply unscrew the pan and drain it that way? How much fluid is going to come out?
Yes, I can rebuild an engine. But when it comes to carburators & auto transissions, I stay the H3ll away in fear
any tips?
AP
Racer
Joined: Jun 2005
Posts: 400
Likes: 11
From: Lubbock Texas
From what I have seen over the years that they do not have drain plugs. Funny how gm couldn' t ad a 50 cent drain plug to their transmissions.
Unbolt the pan & carefully tilt it to one side to let enough fluid out so you can go down with it with out dumping it all over yourself. It can be messy.
Unbolt the pan & carefully tilt it to one side to let enough fluid out so you can go down with it with out dumping it all over yourself. It can be messy.
Le Mans Master
Joined: Sep 2003
Posts: 8,812
Likes: 2,029
From: eastern NC
Years ago I wanted to change the trans fluid in my '77 and decided it was a good opportunity to do something about not having a drain plug in the Turbo 350 pan. After dropping the pan, I checked in the valve body area for a location where a plug would not interfere with anything and welded a 1" square X 3/8" piece inside the pan at this location. I drilled a hole and tapped it for a standard oil drain plug and viola... it now has a factory looking drain plug.
I'm sure that someone out there is now telling folks how his Turbo 350 came from the factory with a drain plug.
As for why the factory didn't do this... well I could tell you about the Mobil engineer that decided changing his own oil in his Rambler was something he could easily handle on his own... but that's another story for another day...
Most of the aftermarket transmission pans do come with a drain plug.
GUSTO
I'm sure that someone out there is now telling folks how his Turbo 350 came from the factory with a drain plug.
As for why the factory didn't do this... well I could tell you about the Mobil engineer that decided changing his own oil in his Rambler was something he could easily handle on his own... but that's another story for another day...
Most of the aftermarket transmission pans do come with a drain plug.
GUSTO
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Instructor
Joined: May 2006
Posts: 153
Likes: 0
From: Cecil County Maryland
I have never seen a th350 tranny with a drain plug. I've always just losened the pan bolts, and let the fluid drain that way.
You'll get about 5-6 quarts to drain out.
It is best to leave some of the pan bolts in until it stops draining. then remove the rest. Warning there will still be about 1 quart still in the pan that youm will wear.
You'll get about 5-6 quarts to drain out.
It is best to leave some of the pan bolts in until it stops draining. then remove the rest. Warning there will still be about 1 quart still in the pan that youm will wear.
Racer
Joined: Feb 2004
Posts: 489
Likes: 29
From: Denville NJ
I have gone the same route as Pete K and draw most of it out through the dip stick/filler port.
I use clear plastic or tygon tubing.
Find the right size that fits the port and slide it in all the way.
Connect this to a trap - jar with large stopper with two holes each with a short tube through holes. Connect one to the hose that is in the trans and the other to you vacuum source.
I use a small hand pump but some of those small 12 volt tire inflaters have a vacuum port also.
It is really easy. Less mess when you finally drop the pan.
You can use the same trap for removing the rear end fluid if you ever need to change it.
I use clear plastic or tygon tubing.
Find the right size that fits the port and slide it in all the way.
Connect this to a trap - jar with large stopper with two holes each with a short tube through holes. Connect one to the hose that is in the trans and the other to you vacuum source.
I use a small hand pump but some of those small 12 volt tire inflaters have a vacuum port also.
It is really easy. Less mess when you finally drop the pan.
You can use the same trap for removing the rear end fluid if you ever need to change it.
