Hiya everyone,

Ok, ive got a question, what would cause gearbox fluid to be pushed out of the breather tube for the auto box??

I noticed this problem one night after coming home along the M1 at about 75mph and as I came off at my junction I stopped for the traffic lights. As I pulled off the car hesitated at the end of first gear before suddenly 'banging' into second gear. It was a real sort of thud and I thought someone had driven into the back of me. It continued to do this for the next few miles as I made my way home and it gradually got better until you couldn't real feel the jolt between first and second.

Next morning I checked the fluid level following the guide in RAVE. The fluid level was right down towards the bottom of the dipstick, past the bottom dimple and only just showing. I topped up until I was just under the top mark and thought nothing more of it. I checked for leaks all round but couldnt see anything. The harsh shifting had gone and that was it.

Fast forward two weeks and I checked the level again, it was right down again and I noticed fluid underneath one of the three breathers that comes up at the back of the engine. I ran my finger under the breather and a drop of red ATF fluid came out, I figured this must be where its coming out from. I topped up again and then spoke to Ashcroft Transmissions as this gearbox is a reconned one from them that I had back in May/June of this year. Its got 10,000 miles on it since then.

Spoke to David Ashcroft who said to do a full fluid change which I did with the help of my specialist. We drained out the oil and checked for any swarf. We didnt see any and only a minimal amount on the gearbox sump plug which my mechanic felt was normal and generally less than he usually see's on gearboxes.

Fast forward to a few days ago when I checked the fluid again. It was right down again with more evidence of it coming out of the breather tube at the back of the engine. I topped it up yet again and phoned Ashcrofts back up.

While waiting for them to get back to me I did another trip on the motorway and stopped at a garage to fill up with diesel. As i walked back to the car I could see drops of fluid on the ground. Fearing this was the ATF fluid again I popped the bonnet and had a look. I could see evidence of it having come out of the breather tube again and now it had also come out of the dipstick tube!

Next thing to try is replacing the gearbox sump apparently. Im not convinced at all this is the answer as there is no damage to the current one and I cant see why changing it would make any difference?? Am I jumping to conclusions too fast and is there a real reason for changing the sump OR is this just a stab in the dark sort of thing??

I dont have much clue about the auto gearbox and I think Im going to have to read up on it but I need some ideas as to why the fluids being pushed out of the breather tube and now the dipstick tube. Im hoping Ashcrofts know their stuff and changing the sump will magically sort everything out but im not yet convinced

Any suggestions??

-Wills

dunno if this is any help. I had a similar problem on an older auto box. the fluid was being sucked up the vaccum pipe that controlled the gear changes. this was caused by a split diaphram in some sortta one way valve.

so long as you kept moving it was fine but if you slowed down or stopped you had to fill up again.

i've no idea if your box is all electronic or has this vaccuummmm pipe on it but it might be worth a look to see if there is any way that the engine is somehow pressorising the g/box.

Thanks for the reply slob, am going to try and have a read up of how the gearbox works and how it achieves gear changes etc. Hopefully I can then figure out exactly why the gearbox would create enough pressure to blow the oil out of the breather and dipstick.

Have spent most of the day trying to clean the driveway up a bit, the gearbox oil has just made a wonderful mess all over the place.

Not only that ive also noticed a very small diesel leak from the injector pump when the vehicles cold and one of my engine oil cooler pipes has started leaking as well. They say these things come in threes - wonderful

-Wills

Hi There,
Just a suggestion, but I think the last post was daft. I would suggest draining the ATF fluid from the 'BOX' and removing the sump, you will find a filter inside the gearbox that 'cleans' the hydraulic fluid before it is recycled around the system. Go for this first as it's a lot cheaper htan having the 'BOX' rebuilt. Cheers, Ian.

what the fook is daft about it??

a filter problem would most likely mean it was blocked therefore no fluid would circulate and you would get no drive. fluid coming out the breather and dipstick tube would not be caused by a blocked filter.

over filled might get yer fluid coming out the dipstick tube(which he says int the case) or pressure getting into the box from some other source which would be limited to the engine.

so explain why the last post was daft.

Well... Erm... I've had the snip but never had a problem getting the fluid of of my dipstick, blocked filter or not! (draw your own conclusions!!).