Transmission Fluid Leak

#21
BW35 Trans Fluid Leak/noisy reverse gear - PROBLEM SOLVED

Dear Rover friends,

just to give you an info, he Problem is finally now (I hope) solved. I bought an rebuild BW35 which is now installed in my car.
I did not have too much time to test now, but until now it drives fine, losing just somedDrops of oil (parking).

Kind regards
Richard



In that case it may be that the converter has drained back into the gearbox itself, artificially raising the fluid level, and causing some fluid to leak out.

Hello P6 friends,

- my BW35 is still losing much oil (Bw35 was rebuild in circa 2010 by Rover Club Austria) and again in 2013 (reverse gear did not work anymore),
but it seems, they did not do a good job, because it is still losing much oil. my workshop said, the oil is not draining back from converter. (?)

- since a few weeks, the reverse gear of my BW35 sounds very rough and loud.
- I must fill up auto trans fluid now every 80-100 km, because the trans starts to slip.

OIL: what is the secret, to solve the problems? is it just a seal? (I am always using castrol TQF fluid)
NOISE: I am worry about this noise.

do you have any advice? I am scary to have again an auo trans box damage. :shock:
kind regards, richard
BW35 Trans Fluid Leak/noisy reverse gear

In that case it may be that the converter has drained back into the gearbox itself, artificially raising the fluid level, and causing some fluid to leak out.

Hello P6 friends,

- my BW35 is still losing much oil (Bw35 was rebuild in circa 2010 by Rover Club Austria) and again in 2013 (reverse gear did not work anymore),
but it seems, they did not do a good job, because it is still losing much oil. my workshop said, the oil is not draining back from converter. (?)

- since a few weeks, the reverse gear of my BW35 sounds very rough and loud.
- I must fill up auto trans fluid now every 80-100 km, because the trans starts to slip.

OIL: what is the secret, to solve the problems? is it just a seal? (I am always using castrol TQF fluid)
NOISE: I am worry about this noise.

do you have any advice? I am scary to have again an auo trans box damage. :shock:
kind regards, richard
 
#22
BW35: I suddenly experienced the same leak. One day there was a small pond on the floor. After refilling everything is honky-dory until the car has been standing for xx hours/days. Harvey states that the check valves very often do not work, but then most of us should experience the problem. Or?
Besides is the any cure apart from total dismatling? If not so I better replace with my somewhat younger spare engine with BW65. That is, if only I can find a rear mounting and a selector cable...
 

harveyp6

Well-Known Member
#23
The check valves in the valve block don't work very well. Some BW35/65/66 have a valve in the cooler return line and you could fit one of those if you can find one, or if not ISTR someone I know made a few.
 
#24
Good idea. Who might that be?

Besides I came to think: Where would the overflow typically come out. Is there a breather of some kind somewhere or is it by some some spindle - speedo drive - shift rod - anything?

An engineer (I) come to think "communicating vessels": If the (un)inteded breather is further up, the fluid wiil stay in the system and simply be pumped back to where it should be next time the engine is started.
 

harveyp6

Well-Known Member
#25
Solid dipstick tubes have a metal breather tube and there were problems with early ones which led to a modification to move the breather pipe up the tube. Later flexi tubes have a plastic breather pipe which ends around the gearbox main case/tailshaft housing joint.
 
#26
There may be something there. I shall check when back at the garage. If the breather tube does NOT pass/end over the top level of the converter, spills may/will occur if air can anyhow slip into the converter when the car is left standing idle...
 
#27
Parts catalogue illustration: According to the engine number my car should have this version. Later ones are quite similar. As can be seen the engineers clearly thought about communicating vessels. Even if the check (non-return) valves are inoperative the 'up-and-down' breather will prevent spills, but only if the 'up' part is completely airtight. I now know where I shall start fault-finding.
 

Attachments

#28
I found my leak: It comes dripping out from the sleeve around the bottom end of the kickdown cable. So nothing wrong with the breather. But if the breather tube (communicating vessels) should be of any benefit, the bottom end of the kickdown must be airtight. And is it really supposed to be that? Nevt, at the same level or just a cm. up comes the shift linkage and the inhibitor switch. Same thing: Supposed to be sealed and tight???.
 
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