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Gearbox disaster

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Posts: 25
Joined: Sun Nov 25, 2018 10:29 pm
Location: Mansfield

Gearbox disaster

Post by keithj » Sun May 19, 2019 5:38 pm

It was really good to meet everyone at Quorn this afternoon. It was our first “proving” run to find any problems. I found a problem. On the way back I dropped all the auto fluid on the floor and continued with the help of the RAC. This also happened when I first drove the car home after buying it but it has been fine since then. I assumed it had just been low on fluid but now I suspect a problem that occurs after about 50 miles. I have done a few trips but nothing over 20 miles. As the gears work fine and the fluid is still nice and pink ( albeit on the road) I am thinking torque converter,. Anyone got a suggestion for a good garage in the Mansfield area to sort it?

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Joined: Wed Aug 08, 2018 8:02 pm
Location: Leicestershire

Re: Gearbox disaster

Post by Superfly » Sun May 19, 2019 9:16 pm

Hi Keith
Met you at Quorn today,sorry to hear of your difficulties.
It's a strange one this is,as you say the gearbox changes gear fine but dump's it's oil after 50 miles,not once but twice.
Maladjustment aside,Automatic boxes don't tend to limp along if they go wrong and you usually get some warning signs of impending failure.
Have you located the source of the leak,is it blowing it out of the dipstick tube?
There's no breather on the BW35 box, but check the dipstick breather isn't blocked or damaged, it's at the top of the tube,
If pressure builds up it will find the easiest way to come out.
Triumph Stags appear to suffer from this issue,same gearbox.
1968 Daimler 250-V8 Saloon

Ian Slade
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Joined: Sat Feb 13, 2016 9:54 am
Location: Akrotiri Cyprus

Re: Gearbox disaster

Post by Ian Slade » Mon May 20, 2019 4:57 am

It is possible there is air in the system, if the previous owner has split the system then it is possible that when refilled there is an airlock to the cooler and you will dump oil either after a 20mile fast run or a longer run.
Owner since the 70's, Genghis is slightly to my left.

Posts: 25
Joined: Sun Nov 25, 2018 10:29 pm
Location: Mansfield

Re: Gearbox disaster

Post by keithj » Mon May 20, 2019 8:43 am

When I first noticed the problem at the fuel station a large puddle developed very quickly when the engine was running. It was literally dripping like a tap. While everywhere was wet it seemed to be coming from between the gearbox and engine hence my thought about the torque converter. After waiting for the RAC it had cooled down and I drove it in and off the 2 flatbeds that took us home. It was not leaking then and I suspect that if I filled it up now it would work OK. That was the symptom last time. Perhaps the suggestion of poor cooling is on the right track, I will investigate further tonight.

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Location: Twickenham

Re: Gearbox disaster

Post by Chris_R » Mon May 20, 2019 9:00 am

About 20 years ago I had this problem in a Triumph Stag with the BW35 gearbox, after almost exactly 50 miles of driving. As far as I recall there is a breather pipe which should be a hard black plastic tube with an inverted U loop at the top. Again, as far as I recall this being blocked led to excess pressure which forces out the fluid through the dipstick tube which then runs down and appears to be coming from the converter area. The breather connects to a spigot above the sump pan.
Consulting the SOC Forum the solution appears to be use the car more frequently! It appears to happen on little used cars. If it's not the breather pipe the issue appears to be the non-return valve in the converter. It can happen on new converters too. Of course this information relates to the BW35 as fitted in the Stag but it may be helpful.

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Re: Gearbox disaster

Post by tjt77 » Wed May 29, 2019 7:22 pm

fluid dripping between engine and box when engine is running in the manner you describe is most likely a sign that the front seal that wraps around torque converter has failed.. I have the self same issue with a Mk2 jaguar that was standing unused for many years ( with the same DG box as used in SP 250) ..on those BW DG boxes the front seal tends to come loose with age and fall out of its housing.. the BW 35 has better location of front seal..but the seal is easily damaged if care is not taken in removing box.. OR torque converter is left in situ when removing or replacing the gearbox.. the torque converter should always be removed WITH the gearbox .. seal is very easily damaged if this route is not strictly adhered to..

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