Transmission Leak ???? TH350

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

bob - 17 Feb 2006 04:04 GMT

This is a 1970 Cutlass that originally had a 2 bbl carb so I assume it is a
TH350 tranny. Have fluid dripping from the back end of tranny but after
wiping everthing dry, it is dripping from the inside of the U-joint, between
the yoke and the cross if I am describing this right (the seal on the
outside that is visible is dry). What seals this? Do I need to take the
tailshaft off or is there some sealing required on the spline as the yoke
assembly is slid in? Kinda confused as I didn't know there was a leak in
this area to fail.. What to I need to replace?

Thanks,
bobby

Reply to this Message

will350@eskimo.com - 17 Feb 2006 14:13 GMT

I'm not "absolutely,
positively" sure,but I think there is a soft plug in the aft end of the
yoke to seal off the splines.

Reply to this Message

bob - 17 Feb 2006 18:22 GMT

> I'm not "absolutely,
> positively" sure,but I think there is a soft plug in the aft end of the
> yoke to seal off the splines.

Thanks for the message and I will have to pull it apart to see what is going
on but trying to determine if it is a 30 minute job or 4 hrs. Another note
is the fluid is constantly dripping and the car hasn't been driven in a
couple of weeks. I've pulled the drive shaft on Fords before and no fluid
ran out. Is Olds (GM) different or is there a seal in the tail section that
has failed and letting the fluid to the spline in the first place?

Reply to this Message

Don - 18 Feb 2006 15:32 GMT

>> I'm not "absolutely,
>> positively" sure,but I think there is a soft plug in the aft end of the
[quoted text clipped - 6 lines]
>ran out. Is Olds (GM) different or is there a seal in the tail section that
>has failed and letting the fluid to the spline in the first place?

If the check valve that keeps the torque convertor full doesn't seal
properly the transmission will gradually overfill as the torque
convertor drains down thus causing the output shaft splines to be
submerged in fluid where they are normally only exposed to splash. If
you start driving this car daily you may not have significant leakage
from the transmission tail. There is no seal to keep fluid out of the
tail housing. There is a plug in the yoke. Sometimes it is vented,
sometimes not.

Don
www.donsautomotive.com

Reply to this Message

bob - 20 Feb 2006 16:56 GMT

> >> I'm not "absolutely,
> >> positively" sure,but I think there is a soft plug in the aft end of the
[quoted text clipped - 18 lines]
> Don
> www.donsautomotive.com

Don,

Thanks for the note. I assume this check valve is in the torque converter
so the fix is to replace torque converter? Also, is there a problem sealing
the end of the yoke (not sure how to do this yet as I haven't pulled it
apart yet but I'm sure it is possible).

Several weeks ago, the car was a little low on fluid (on the end of
dipstick) but took over a quart to get back to full. I don't check this
very often so not sure how long it has been there but when starting from
cold, it acts like it is low on fluid as it takes several seconds to shift
into reverse or drive the first time. Shifts fine after that. Maybe this
is another symptom of bad check valve?

Thanks,
bobby

Reply to this Message

lugnut - 20 Feb 2006 19:50 GMT

>This is a 1970 Cutlass that originally had a 2 bbl carb so I assume it is a
>TH350 tranny. Have fluid dripping from the back end of tranny but after
[quoted text clipped - 7 lines]
>Thanks,
>bobby

The yoke probably should be "vented" so that air does not
get trapped inside the yoke making it transfer shock between
the drive shaft and the trans tailshaft. Fluid should not
be high enough to leak out the rear. Splash is about the
only lube there should be back there. Some of the tail
shalves have an "O"ring that the front of the yoke slips
over to keep any fluid from the spline area but, I do not
recall if that is the case on the THM350. Make sure the
trans is not over full which will do this. The torque
converter may be draining back but, it can only drain about
3-4 quarts at most this way. This should not be a problem
if the vehicle is sitting on level ground but, if it is
parked with the nose up in the air, it could be if the trans
is overfull a bit.

Lugnut

Reply to this Message