Author Topic: Leaking Trans Fluid  (Read 2372 times)

Offline Spool

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Leaking Trans Fluid
« on: April 18, 2021, 11:27:32 AM »
Hey guys.
73 C20 here.

I'm also leaking trans fluid from my driveshaft! It appears every single part my 'infamous mechanic' touched has a new problem.
I had him give me a transmission service back in Dec as I was having trouble engaging in first on a cold start.

I've attached pictures, but I appear to be leaking fluid on the driveshaft and on the edge of the pan as well.

Thinking, I'm going to just take this into a shop as it appears to be leaking from multiple places...
At first, I was thinking the seal gave out where the driveshaft meets the trans, but after seeing trans fluid along the edge of the pan too, I just felt utterly defeated at this point with so many things going wrong at once after my mechanics service. Any thoughts?

Offline JohnnyPopper

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Re: Leaking Trans Fluid
« Reply #1 on: April 18, 2021, 02:05:07 PM »
Your drive shaft doesn't hold any fluid so as to leak, likely being blown on it from the pan while driving.

Doesn't look like your rear seal is the problem either.

Try tightening your pan bolts, (not over tighten) before you take it in. You may find that takes care of it.
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline skinu

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Re: Leaking Trans Fluid
« Reply #2 on: April 18, 2021, 06:13:30 PM »
There's a hole in yoke end seal with silicone ,the seal on tail end housing can be serviced while there but the fluid is coming off the spines of the output shaft. This is kinda supposed to be a controlled leak but wear makes it fill the yoke and leak.can be done externally but if yoke is removed and silicone is put on from inside it's more permanent.

Offline bd

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Re: Leaking Trans Fluid
« Reply #3 on: April 18, 2021, 11:01:43 PM »


Leaking Driveshaft Yoke   Yoke leaks such as imaged above are rarely the result of poor service methods.  The o-ring simply loses elasticity over time with normal heat cycling.



700R4 Won't Stop Leaking  Different transmission, but the same principle.





What is the color of the fluid droplet forming in this image - red transmission fluid or brown engine oil?

Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Spool

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Re: Leaking Trans Fluid
« Reply #4 on: April 19, 2021, 09:09:04 AM »
Thanks, guys.

BD, the second image you questioned is actually an oil leak.
I believe I have always had a small leak at my rear main seal that makes its way down to the oil pan.

I recently parked on concrete the past few days as opposed to grass per usual, which allowed me to spot the leaks.
I placed cups of water beneath each pool of liquid and found that my trans fluid is leaking 'from' the yolk, and three spots along the pan as well.

But, further up towards the engine, BD, is in fact, a small oil leak.

I'll attempt to tighten the trans pan bolts, Johnny before bringing it in somewhere. Are there torque specs for that? About 10ft/lbs?

Offline JohnnyPopper

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Re: Leaking Trans Fluid
« Reply #5 on: April 19, 2021, 05:41:18 PM »


Leaking Driveshaft Yoke   Yoke leaks such as imaged above are rarely the result of poor service methods.  The o-ring simply loses elasticity over time with normal heat cycling.



700R4 Won't Stop Leaking  Different transmission, but the same principle.





What is the color of the fluid droplet forming in this image - red transmission fluid or brown engine oil?

I can't see how that o-ring keeps oil out of the spline. ??? It doesn't come in contact with the yoke, as it is constantly moving in and out of the tail stock. Is it sandwiched between the output shaft and the tail stock? I could see that as a possibility.
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline JohnnyPopper

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Re: Leaking Trans Fluid
« Reply #6 on: April 19, 2021, 05:44:56 PM »
Spool,

I've never used a torque wrench on pan's, just do it by feel. Sure there is a spec...
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline bd

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Re: Leaking Trans Fluid
« Reply #7 on: April 19, 2021, 09:59:44 PM »
I can't see how that o-ring keeps oil out of the spline. ??? It doesn't come in contact with the yoke, as it is constantly moving in and out of the tail stock. Is it sandwiched between the output shaft and the tail stock? I could see that as a possibility.

The o-ring (#691) rides directly against the smooth bushing surface of the slip-yoke.  By design, the splined open end of the yoke remains positioned and effectively shrouded inside of the sleeve (#690) at all times.  Now, the forward end of the sleeve is a light press fit over the output shaft and seals tightly against the shaft.  Hence, the o-ring seal, sleeve, output shaft, and yoke, together, function as a mechanical system to isolate the open end of the yoke from fluid emersion and direct splash.  If that o-ring doesn't seal efficiently so as to manage fluid migration into the small chamber created between the end of the yoke and the sleeve, any fore and aft movement of the driveline will effectively pump fluid past the splines and out the vent hole hidden behind the u-joint.  The result is an unrelenting, messy, and very annoying fluid drip.  Capiche?
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Spool

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Re: Leaking Trans Fluid
« Reply #8 on: May 01, 2021, 11:57:20 AM »
Last week, I went and tightened the bolts on the trans pan- there was room to be tightened for sure without really wrenching down on them.
I wiped it off and kept an eye on it, but it appears I still have a small leak. I can see the mess it makes in the driveway (gonna have to scrub that down and clean it up as it's not my driveway.)

Furthermore, it's a real mess down there. Makes me wish I had a larger budget to start tackling bigger jobs on the truck to get her closer and closer to perfect.

My current mission right now is to eliminate leaks and squeaks with a priority on leaks.

However, I keep checking the trans oil dip stick after driving for a mile or two and the levels seem fine. Strange?

Offline Mike81K10

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Re: Leaking Trans Fluid
« Reply #9 on: May 01, 2021, 06:42:19 PM »
I have found that tightening trans pan bolts never work once you have a leak. Only solution I have found is to pull off the pan and replace the seal with a new one. It is inexpensive to do and can help keep your driveway or garage cleaner. You can also change out the filter/screen if needed while you're at it.
« Last Edit: May 01, 2021, 06:45:43 PM by Mike81K10 »
"Tell me and I forget. Teach me and I remember. Involve me and I learn." -Benjamin Franklin

Offline JohnnyPopper

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Re: Leaking Trans Fluid
« Reply #10 on: May 02, 2021, 02:24:40 PM »
Yes if you're in it that deep, by all means change the filter. A clean transmission will live a long time.
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction