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Post by mongoose on Nov 9, 2010 16:06:05 GMT -5
I've had my '65 Cutlass since 1985... so I thought I had pretty much seen everything on this car.
I recently got the new motor running... and over the last 10 days or so the car has sat on 4 jack stands so we could put a new exhaust system on it... bleed the brakes, etc.
The other day I saw that some transmission fluid had leaked on to my drain pan (just in case). With the car nearly 3' off the ground, it was easy to crawl underneath and find the source. I figured it was probably the drain plug needing to be tightened a bit after letting everything heat up.
I traced the drip to the driveshaft yolk, and saw a drip forming off the u-joint. Anyway so I figured the new tailshaft seal wasn't sealing right, or that maybe I had some grooving on the yolk itself allowing fluid to get by. So I wiped everything off really good, and gave it 24 hours so I could get a good look where the leak was.
What I found still has me scratching my head...
There appears to be a small hole in the center of the driveshaft yolk itself, and transmission fluid is trickling out of that hole, and tracing its way down the yolk to the lowest point it can find before it drips off.
So what the hell is that hole, and why would it be open to the tailshaft itself that would allow transmission fluid to work its way through the output shaft spline and out this hole? It's never done that before that I know of, but then again I have historically had trouble with a chronically leaking dipstick tube seal before I replaced it with one of the "new" styles that uses a "boot" to seal the tube to the transmission (instead of an o-ring). So I could have had a leak at the rear too, and just not realized it.
So why is this hole there... and why would it be leaking???
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Post by mongoose on Nov 9, 2010 17:24:50 GMT -5
Forgot to mention the transmission is a TH-400.
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Post by BR[] on Nov 9, 2010 18:14:39 GMT -5
Sounds like you need to get your mig out and give it a touch.
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Post by otis1965 on Nov 9, 2010 18:34:14 GMT -5
i had the same problem when i had a new drive shaft made i had the hole welded shut
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Post by rickman on Nov 9, 2010 19:49:41 GMT -5
If the hole will slide into the seal when it's on all 4's, you won't have to do a thing!
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Post by mongoose on Nov 9, 2010 20:21:52 GMT -5
The hole is in the very center of the end of the yolk (in line with the center of the output shaft... and looks like it is supposed to be there, but for the life of me I could not come up with a reason why. If none of you have seen this before, it sounds like it's something that needs to be "fixed".
The only thing I could come up with is that it vented the yolk as it slides back and forth along the transmission output shaft as the suspension travels up and down, to prevent suction and pressure between the cavity of the yolk and the output shaft.
I don't know... just reachin'. But if that is the case, then something else is "up" allowing transmission fluid to fill the inside of the yolk, and then to seep out of this "vent" hole.
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Post by otis1965 on Nov 9, 2010 20:47:11 GMT -5
thats where mine was we tried silicone but welding worked no more leaks
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Post by Big Mike on Nov 10, 2010 11:41:05 GMT -5
The hole is in the very center of the end of the yolk (in line with the center of the output shaft... and looks like it is supposed to be there, but for the life of me I could not come up with a reason why. SNIP The only thing I could come up with is that it vented the yolk as it slides back and forth along the transmission output shaft as the suspension travels up and down, to prevent suction and pressure between the cavity of the yolk and the output shaft. No, you are not reaching, that is exactly what that hole is for, to vent and so you can actually be able to install the drive shaft and so it will be able to slide back and forth while driving. If you didn't have a hole, it would be hard to install and operate properly, especially on a properly sealed transmission. The car is most likely ever so slightly higher in the front causing the fluid level to shift enough to leak out the hole. Or, it could possibly be slightly over filled as well. |
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Post by mongoose on Nov 10, 2010 16:22:47 GMT -5
Or, it could possibly be slightly over filled as well. I guess it's possible it got overfilled while I was breaking the motor in... although I obviously tried to be careful in filling it. The thought of the pan being overfilled entered my mind... as the leak didn't appear until about a week after the car had sat... allowing fluid throughout the transmission to gradually drain back into the pan. So if I had over filled it somewhat, then perhaps that created the opportunity for the fluid to work it's way out the "vent" hole. I have a new filler tube/dipstick in this transmission that I found the read to be kind of sloppy... there were signs of fluid here and there on the stick when I read it... and I thought there must still be some clinging to the sides of the tube. When cold, about where should the fluid level read? Maybe a quart low? Of course it would make no sense for me to check it now without starting it up, as there is probably excess fluid in the pan from it sitting for about 2 weeks. Or maybe another way to look at it... about how far should you expect the fluid to read after the car has sat like mine has? That probably an impossible question to answer. |
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Post by mongoose on Nov 10, 2010 16:47:04 GMT -5
Just checked the fill level. The fluid level is 2 1/2" above the top of the "Hot" range on the dipstick. Again, the car has not been started in 2 weeks, so I know fluid has drained back into the pan.
Any thoughts on where this should be? My vote is on the "over-fill" category at this point.
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Post by Big Mike on Nov 11, 2010 10:19:55 GMT -5
Just checked the fill level. The fluid level is 2 1/2" above the top of the "Hot" range on the dipstick. Again, the car has not been started in 2 weeks, so I know fluid has drained back into the pan.
Any thoughts on where this should be? My vote is on the "over-fill" category at this point. Is the level 2½ inches above the "Hot" level with the engine and trans warmed up and engine running? If it is, then it's waaaaay over full. If it's 2½" with the trans cold and engine off, then maybe not, but it still sounds a little high. |
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Post by mongoose on Nov 11, 2010 11:41:45 GMT -5
No... that's the reading I just checked with the engine and transmission about 10 days cold. Last time I started it was on Halloween night for a group of party-goers.
I didn't know if anyone else had easy access to their car, with a TH400, that's sat for a period of time, where they could check the fill level on their dipstick. Could always hope anyway. Worse case I can just start her up again! ;D
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Post by bil on Nov 11, 2010 20:25:10 GMT -5
+1 on Mikes advise-I had the same thing happen with the T400 on my 70-when it was at the right angle anf a bit over full,it would seep out the hole.And if you hold your finger or a string,etc,by the hole when you slide it on the output shaft,you will notice that the air DOES come out.I also believe that is what it is for.JMO ---bil
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