a 727 tranny leak question

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trudysduster

trudysduster

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I have a leak on my 727. It doesnt leak until I park it and it seems to leak over night. I guess the torque convertor is draining back to the pan. I have changed the pan gasket and even put on a new TCI pan thinking that was the problem. I changed the dip stick o-ring and it isnt there. I am leaning towards the driver side area. I have been told the problem might be in the shift lever or kick down lever seals. The question is I have been told that if I put a deep pan on it that the fluid level will be lower than the seals and it will not leak. What are your thoughts on this. I do not want to lay under the car for hours waiting for this to start leaking to see where it is coming from exactly. But it looks like it is leaking somewhere on the driverside and running down and around the bottom of the pan. Will a deeper pan fix the leak if it is coming from the seals. I have never put them in before. Any help would be appreciated.
 
I would think you'd simply add 2 quarts to make up for the pan thus the fluid level will be the same in either. The dipstick is still at the same level. So don't think that will help you out.
 
If you replace the seals on the shift lever /kickdown and the neutral safety switch, and it still leaks, look at the back of the trans.Above the pan. There is a shaft that is the pivot for the rear band. It has an O ring on it. I chased a leak for years until I found out that the builder (ATI) was too lazy to change it. You have to drop the pan, pull the rear housing and loosen the lever adjustment to remove the pivot rod and change the O ring. When you remove the pan you will see what needs to be done. Hopefully it's just the shifter seal.........
 
deep pan with the filter extention without the 2 extra quarts is a getto solution. you can do the shifter seal with the trans in the car. the service manual has ok instructions. just read it through a couple times.
good luck
 
There is no seal on the front band adjuster and I have seen them leak if their not tight enough. Generally if their tight they don't leak. May seep a little but not leak. And they generally don't even do that setting as it's up higher than the fluid level. Also as mentioned if you install a deep pan you should still fill it to the full mark (when completely warmed up) on the dipstick when otherwise your defeating the purpose the deep pan provides which is extra fluid. The speedo housing is a very common leak. Sometimes the large o-ring on the outer perimeter leaks but most of the time it's the inner seal that leaks. If it is the inner seal the best fix is to install a seal from a (dare I say) Chevy Turbo 400 as they are a spring loaded seal that seals much better. The shift shaft seal can also leak as can the throttle pressure linkage (kickdown) shaft seal. You need to clean it up good and run it and inspect it closely to determine exactly what is leaking.
 
thanks guys, I am in the process of pulling it and replacing all the seals and o-rings to make sure. Will update you.
 
can anyone give me NAPA part numbers for the shift shaft, speedo and any other possible leak causing seals on the 904? All I get is blank looks when I ask for it and have no success on google.
 
jpywell52 said:
can anyone give me NAPA part numbers for the shift shaft, speedo and any other possible leak causing seals on the 904? All I get is blank looks when I ask for it and have no success on google.
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Have you tried looking them up on NAPA's website? It's www.napaonline.com I get the same blank stares from some of the guys at my local NAPA so I just look things up online and give them the part #'s.

as for what's leaking there are several things that can leak. Your best way to tell what is actually leaking is to clean it up real good with a pressure washer or carb/brake clean if you don't have access to a pressure washer, then run it in gear with the wheels jacked up and supported and watch to see what's leaking. The shift shaft and throttle pressure seals are likely candidates as is the speedometer shaft seal. If it is the speedometer shaft seal I use a seal from a Chevy turbo 400 cause it's a spring loaded seal that seals much better. Like Kim said the lines can leak too. Front pump. Extension housing seals. Filler tube O-ring and there's an O-ring on the pin that holds the rear band mechanism in place. It's partly captured by the extension housing. The extension housing seals can leak. Basically there isn't a seal that can't leak.
 
National part number is 8609. If that's not the number NAPA uses, they should be able to interchange it.
 
Thanks guys, my slant six oil leak just got WAY worse this week and I'm afraid it may be time to pull the whole works and go through all the seals. I'm leaving a 1 quart puddle of trans/10/30 every night.
 
the low band shaft does have a o ring,it is towards back tranny,drivers side above the pan,the tail shaft has a piece that sticks out over the shaft preventing it from coming out,I bet your leak is right there,a shot rodder fix is to clean area real good,and put some black RTV in the indentation,you probably need to drain the fluid down a bit before cleaning,Rtv it let dry,it will solve your problem,not a permenate fix but until you want to drop pan and do it right? give it a try.
 
trudysduster said:
I have a leak on my 727. It doesnt leak until I park it and it seems to leak over night. I guess the torque convertor is draining back to the pan. I have changed the pan gasket and even put on a new TCI pan thinking that was the problem. I changed the dip stick o-ring and it isnt there. I am leaning towards the driver side area. I have been told the problem might be in the shift lever or kick down lever seals. The question is I have been told that if I put a deep pan on it that the fluid level will be lower than the seals and it will not leak. What are your thoughts on this. I do not want to lay under the car for hours waiting for this to start leaking to see where it is coming from exactly. But it looks like it is leaking somewhere on the driverside and running down and around the bottom of the pan. Will a deeper pan fix the leak if it is coming from the seals. I have never put them in before. Any help would be appreciated.
Click to expand...
I just did the shift seal on my 727. I had to turn the tranny on it's back and pull the shift rod out a ways to get to the shaft. What happened to mine is that id developed corrosion on the shaft and I had to work it over with emery cloth in order to get rid of the pitting from where the fluid seeped, then add the new seal. Bill
 
A lot of good suggestions here. If I could make a suggestion here's one. Clean the affected areas off realy really good with brake clean & compressed air if you have it, then spray the areas around the pan gasket & shift & Kickdown seals, cooler lines & don't forget around the bottom of the dip stick tube with ordinary athletes foot powder spray. Spray it on good & wet & then drive it as normal until it leaks. The powder will show the leaking area & should still be dry where it doesnt. Or you could add some oil leak dye in it & check it with a uv light if you have acceaa to one. Good luck!
 
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