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Gearbox/Overdrive oil leak


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I've got a problem with my 61 3a in that I've got an oil leak that has developed between the back of the gearbox and the overdrive. I should add that I purchased the gearbox and overdrive as a fully refurbished unit from someone that I know 3 to 4 years ago but I've only just got round to installing into the car which is nearing a lengthy restoration. The box and overdrive has been recently tested and all seems fine but soon after I noticed the oil leak which I thought initially was coming from the large brass drain; I purchased the correct spanner and fitted a new washer but still the oil leaked. After lying under the car yesterday for best part of half an hour I could see that in actual fact its coming from the seal directly above the drain which hopefully you can see from the attached photo. This is taken looking towards the back of the car with the overdrive directly in front of you. It may be difficult to see but the oil is collecting on the horizontal joint and then running down the casing to the drain plug. The leak is quite steady and overnight probably equates to an egg cup full of oil and this is when the oil is cold, fresh out of the can. The oil that I'm using is 80W/90 by Motoquip (see attached)

 

I was intending to take the box out and have the gasket replaced but noticed an old posting last night from 2016 started by Martin (Mart O) in which Tom (Fireman 049) suggested using a product called 'Oil Tyte' which is available from Frosts and appears to be a stick that is rubbed into the joint and operates up to 15 PSI (1 Bar). Tom mentioned at the time that its cured his leak but I'm just wondering if anyone have any experience of using this product?

 

Graeme

 

 

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Hi Graeme ~

 

+1 for Oyltite. I used it to cure a leak between the gearbox and overdrive a few year ago and it's still going strong.

The secret is to use a sharp scraper to clear the joint before rubbing in the Oyltite. Make sure all traces of oil are removed.

You need a clean surface all round.

 

Tom.

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I've got a delivery of Oil Tyte coming this Friday, thanks for the tip Peter

 

Tom, just out of interest, was your leak in the same location and do you think it may be worthwhile slackening off the nuts securing the overdrive to the gearbox in order for me to work the stick into the gap more effectively?

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Hi Graeme ~

 

My leak was at the back of the gearbox so I wasn't able to slacken off the bolts.

In your case I'd be inclined to slacken off the securing bolts a little inorder that you get as much Oyltite in after you've completely cleaned

the outside surfaces first. But be careful, slackening the securing bolts may allow oil to leak out?

 

Tom.

Edited by Fireman049
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Thanks Tom, I think you're right, I've ordered some new fixing nuts as mine are looking a bit rounded and am planning to drain the box; clean thoroughly with carb cleaner and work the Oil Tyte into the gap. I'm a bit concerned as I'm told there's a bloody great spring behind all of this so I just want to slacken off a bit to allow me to form a good seal.

Graeme

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Elin in Canada has done a series of videos on our boxes and overdrive

This video shows the joint with the plate and box which is possibly your leak area. But the bolts are inside

https://youtu.be/cgNadKy16QE

Hopefully yours is od to plate in which case those bolts you can see.

 

I found this in mine after a season of sprints etc.

https://youtu.be/YD1kA-zdiLY

https://youtu.be/ettXA5EJ_OM

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Back about 1965, I opened up the gearbox and overdrive in my 1958 TR3A. (I can't remember why !). I forced it back together on assembly but while tightening the long side stud nuts, I bent the oil pump assembly at the rear of the overdrive and also put a large crack in the aluminium adaptor plate that fits in between the g/box and the O/D.

 

I replaced the oil pump assembly and it ran fine with the crack but it leaked until, in 1987, I started my restoration by replacing the adaptor plate with a new one. Leakage during the last 115,000 miles has been minimum.

 

Don Elliott, Original Owner TS 27489 L), Montreal

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