Anything and everything Herald. Talk about anything from the first 948s to the last 13/60s.

Clutch, gearbox, overdrive, propeller shaft.

Latest thing is now the 'box has developed a leak from the drain plug. I've tightened it up as much as I dared, that didn't work so I had it off and applied some thick jointing paste which also hasn't worked. It's not a big leak, and as you'd expect not really dependent on how much I use the car. Now I could keep on top of it by regular topping-up but with the price of proper GL4 gear oil, and the mess it's making on the garage floor, it wants sorting.

Any ideas? It's a later type plug (in a later Spit 4-synchro 'box) with a bit of a hex head on it, I've been toying with the idea of a thick lead washer or two but to be honest I ain't too confident of its being a success. Should I try a new plug-mind you there's nowt to see wrong with the present one, no sign of a stripped thread or anything.

Help! It's driving me up the wall!

Dan,
Just a thought...have you tried PTFE threadseal tape; the stuff plumbers use. Its both chemically and heat resistant and worked a treat on my leaking sump plug. Furthermore, its also very cheap and easily available at any DIY store.
Graham
p.s. have a look at the attached. It always amazes me what peer reviewed journals accept for publication (no disrespect to the authors).

Hi Graham,
I'll bear it in mind but to be honest I haven't had much luck with this stuff before, especially on taper fittings-I find a paste is better for those but it just hasn't worked this time. Maybe I need a better compound-I suspect the one I am using (years old) is no more than white lead/zinc oxide in linseed oil, although it has worked well on lines to oil pressure gauges and on plumbing fittings. I've used blue hylomar on iffy sump plugs before, but not taper fittings-the ones you are supposed to replace a copper washer on only you never have one the right size do you... I'm also toying with the idea of red hermetite or similar.

It can't be too difficult to seal can it?????????? Still open to suggestions!

Not much help for a taper fitting, but if you are ever short of a replacement copper washer, you can rejuvenate and reuse the old one by simpy annealing the copper. Just heat to red heat and allow to cool (or quench in water if you are in a hurry).
I've always found PTFE tape good for thread sealant (and it has the benefit that if it gets into the gearbox it won't damage anything, may even be a lubricant! But don't let it get into the overdrive!)
It may be the case that the hole or the plug is slightly distorted. Simply trying a new plug would prove if the plug is the problem, but the solution to a distorted hole would be to run the taper tap though it again. Not so easy.
Not intended for sealant (although sometimes called such) more for preventing threads working loose, but if you can get the threads clean enough, some Loctite threadlock/nutlock/studlock might do the trick. With a taper thread there should be no problems with undoing it again next tme you need to drain the oil, but make sure the squre drive is in good nick and you have a close fitting spanner.

It's not a square drive, it's a hexagon and a fairly large one at that, somewhere around 3/4 if memory serves. Which is probably half the problem..!

The weight of opinion seems to be with the PTFE tape, I suppose I'll get some fresh (maybe had no luck before because it is old?) and try again with it.

Well I went to sort this a few weeks back - been busy with other jobs - only my lamp went and I had to go back under the car with a substitute, and much brighter, bulb. Then I found it's not coming from the drain plug at all but from round the speedo drive and oozing down. Since then I've been messing around in a half-hearted fashion and managed to come up with a new question! Is there an oil seal where the drive sits in the 'box casing that I can replace? The drive seems a bit loose in the casing (retaining bolt is tight) and when I wobble it, a drop of oil appears. Any thoughts on this?

There are two O-rings that are part of the speedo drive assembly - They might have failed.

Thanks for that info. But supplementary question-are these O rings a special item or a standard size?

Section : Gearbox

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