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The mkiv Supra Owners Club

Manual Gearbox breather?


Paul

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No form of pressure relief then, I assume that as with anything mechanical that's sealed it would need some sort of exit as some small pressure must build up during use?

 

Answer to question is that I'm still getting oil weeping despite changing the rear seals twice! Job was done properly, companion flange in A1 condition (had new one waiting but no better than original).

The next stage is to drop the box again and change the seal to the gear lever linkage but also check any pressure release system in case it's blocked and causing a build up?

BTW, no cracks etc in casing.

 

Paul

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I didn't do it but was there throughout both times and yes the shaft looks like new, no wear rings, nothing.

Infact it all looks in exceptional condition but still leaks. As the gear lever linkage is above the output and has a seal then this is the next option, to change this.

I know that the box isn't pressurised as such but is it possible for some to build up?

 

Edit: Some gearboxes do have breathers, I now remember when I've worked on industrial worm type ones and they have breather plugs mounted at the high point of the casing.

Paul

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Not puddles, it's never been that bad, drips on the floor when parked. In all the time it's leaked there's never been a need to top up.

 

I know it's not going to damage the box but I feel it needs doing as it's not right.

We were looking at this gear linkage seal as being the next step and then I saw the post on Supraforums. They seem to think that this seal is more likely to be the cause of a leak than the main output one. We've got the seal on order and it's booked in for a few weeks time.

BTW, I'm in engineering so these things bug me, it wasn't designed to leak so it shouldn't :sly:

Paul

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It will definiteley have a breather, but I can't remember where it is. I am pulling an engine and manual box out next week, I'll look for you if you remind me. The gearbox heats up through friction and heat through conduction and convection from the engine, the air inside expands, if there was no breather the pressure build up could be considerable and cause leaks or even pop a seal.

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It will definiteley have a breather, but I can't remember where it is. I am pulling an engine and manual box out next week, I'll look for you if you remind me. The gearbox heats up through friction and heat through conduction and convection from the engine, the air inside expands, if there was no breather the pressure build up could be considerable and cause leaks or even pop a seal.

 

Cheers Chris, that's what I thought it must have some sort of breather even if it's a simple plug with a pin hole?

That'll be great if you could let me know where it is, need to check it's not clogged up although the problem does point towards the linkage seal now.

 

Out of interest have you replaced the linkage seal before? On Supraforums they talk of not taking the original out and adding the new one infront of it.

 

Paul

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Cheers Chris, that's what I thought it must have some sort of breather even if it's a simple plug with a pin hole?

That'll be great if you could let me know where it is, need to check it's not clogged up although the problem does point towards the linkage seal now.

 

Out of interest have you replaced the linkage seal before? On Supraforums they talk of not taking the original out and adding the new one infront of it.

 

Paul

Never changed one to be honest. That's an old Mini / 1100 / 1300 BMC trick, to put two seals on the gearlever rod out of the gearbox. Sounds a good idea, the outermost one will protect the inner from grit and stuff. i'd put 2 new ones in rather than just one outermost new one, to be really sure. let us know how you get on. Cheers.

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  • 3 weeks later...
Breather is shown at my site below. Also pics of a Supra without engine. Anyone ever wondered if they designed it to also take the lexus 4 litre V8? Looks as if it would drop in nicely.

 

PICS HERE

 

 

DO IT!!!! PLEASE!!! Nice pair of low slung tubbies too :)

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Thanks for that Chris,

been to Phoenix today and changed the linkage seal, obvious play/gap between the rod and the I/d of the seal. Looks like this may have been the problem?

Doubled up by pushing the original in quarter of an inch and then fitting new one on top. To get to the breather it'll mean the box out, will see how this seal goes first.

Did the breather on that one you're working on looked blocked in any way?

 

Thanks again, Paul

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