BW35 leaking - any experiences with leak stop additives?

[Dieter H. Marschall]

Hello,

the BW35 from my Stag is leaking. What additive to the gearbox oil would you recommend to stop the leak?

Maybe I will have to consider a rebuild or building in a ZF4 gearbox. What would be best? What costs will I have to face for both options?

Kind regards,
Dieter.

[RogerP]

Hi Dieter

Gearbox additive, in my experience don't touch it, about 20 years ago when we were in the Netherlands somebody gave me some to put in our BW35 did about 100ml and it then threw all the oil out, had to be relayed home and a complete gearbox rebuild.

If your funds can run to it fit the ZF.................If you are going to the ESM in Cologne there will be a few of us there with the ZF so if you want to try one just look me up and we can go out for a little run.

Rogerp

[Dieter H. Marschall]

Hello Roger,

I will gladly accept your offer and testdrive your Stag with the ZF4 gearbox. I will be there only on Saturday, however.

The problem is that the reconditioning of my BW35 here in Germany costs me about EUR 1400.-.

How much is the ZF4? Who does those conversions in the UK?

Kind regards,
Dieter.

[jbuckl]

About £2000 for a zf conversion.....includes all the parts required.
Tate & Lewis are the zf 4spd people (Clive & Russell) I thought I sent the phone numbers before?

BW 35 can be rebuilt by a competant diy person.
Its the easiest 'box to remove and refit.

1400 euro 'reconditioning' won't necessarily stop leaking.

BW35 can be made 'dry' but the torque convertor anti drain-back valve seems always to cause fluid expulsion on start after a period without use.
The anti drain back valve can allow fluid level to rise too high in the box when not in use.
Things needed to make dry are:- new banjo bolt & dowty seals intead of copper washers for filler tube ( the bolt will not withstand overtightening); repair all sump bolt threads.
Sump gasket~do not use R.T.V./silicone.
New drain plug fibre washer.
Include anti-beaming brackets (often missing)
Replace output shaft lip seal & Clean up the lip seal diameter on the prop.
Replace the shift lever lip seal.
pu sealer on the inhibitor switch~ if there is a leak from it.
Tight fitting tube on the plastic breather adaptor..original was pvc tube.
Oil cooler pipes checked for leaks.
Polish torque convertor output diameter & dog.
New input shaft lip seal.
New oil pump o-ring.
Governor housing (output) gasket.

Be very careful that a non leaking box isn't empty!

The parts are getting quite scarce but try 'jpat' , who still have a bw35 listing. http://www.jpat.co.uk/Borg%20Warner%2035.pdf
Noisey front pumps are a bit of a problem.(thats why i finally gave up with it and put a zf4spd in)

[martin]

Hi Dieter, have you any idea where the leak is ? If it's from the dipstick tube near the bottom, you just need to replace the banjo washers, if from the bottom of the trans, it's the trans sump gasket. Mine's dripped a bit for seven years, like most 35s but the quantity is very small, if messy. Martin.

[DJT]

[QUOTE=martin;137215]Mine's dripped a bit for seven years[QUOTE]

Not surprised after your recent admission to being 150........

[richardthestag]

everything they said above, unless the leak is from banjo joint or something simples then my recomendation in the interim is start buying shares in ATF and this stuff....

pettexpremiumcatlitter154618.jpeg

My BW35 leaked plenty but only after a day or two of standing and then it was always overflow up the dipstick tube because of TQ draining back into the box. Swapped it out for a MAN o/d.

Unless you are an originally freek i'd not bother reconditioning the bw35 especially as it may not fix the leak, it is very expensive and you still have a bw35 at the end of it

My Man o/d convertion was with a very good reconditioned box, new everything else and still came in at about 2/3 the cost of the bw35 estimate for reconditioning.

[martin]

[QUOTE=DJT;137216][QUOTE=martin;137215]Mine's dripped a bit for seven years

Not surprised after your recent admission to being 150........

GIT !

[kemp42]

Cured my constantly-leaking BW35 - have had a BW65 fitted !

[Dieter H. Marschall]

Hello everybody,

Thank you for all your hints. Obviously the leak is in between the torque converter and the gear box, as there are always some drops of gearbox oil at this little plastic grid.

In Germany some garages recommend an additive called "Lecwec", which seems to make the seals swell and become flexible again.

Kind regards,
Dieter.

[jbuckl]

Probably won't hurt seems to cost 30 euros

In the US & UK there is a similar product from Lucas (not birmingham lucas!)

http://www.lucasoil.com/products/display_products_overviews.sd?iid=12&catid=6

I have used this in a rover p5 steering box.....it reduced the leak.
The box was replaced to cure the leak. The design was poor from a seal point of view. (large felt washers employed to soak up seepage from new!)

[Giles]

I have had good results with Lucas additive in power steering but I would always be worried about putting anything in a Auto box. If it is a minor leak I think I would live with it

[Robin Searle]

I know that this is an old thread re the leaking BW35 auto gearbox.I purchased a STAG that had its BW rebuilt by a transmission shop. Tranny fluid leaked everywhere when it was parked,"it's a Stag problem all over" I was told.Despite the car being returned to the transmission shop 4 TIMES and unit removed THREE times,the last time is came back it was worse than ever.My brother,now retired,came over and said let me have it,I went on vacation and on returning Ian gave me the GOOD news,the transmission shop had NEVER fitted the breather pipe that goes up to behind the wiper motor.He fitted a thick wall pipe which really connects with the nipple on the unit and it never now drips at all.