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MG Midget and Sprite Technical - Gearbox noise

Hi Guys. I have a buzzing noise from the gearbox which I was told required an anti-rattle kit to stop it.I duely purchased and have just fitted same.Unfortunately there is no difference.However while I was delving into the box I noticed a large build up of rusty coloured goo in the casing.Is it possible to add an engine flush to the box and clean out all the crud,then replace the oil.
Another question.Which oil should I use.Standard or modern synthetic?
I.M. CHRISTIE

NOPE !!! Dont do that !

Thats a BAD idea, what happens with aged engines and im betting a wooden nickle the same applies to the 1275 gear box that has not been serviced regularly is a sludge builds up inside all the bearings and close spec tolerance spaces and it becomes gap filler

If you clean all that junk put that has been there for 1000s of miles, and years of build up...then those gaps and spaces are to big, and the gear box will fall apart in about 800 miles and go bang

If you didnt have the brown goo grease, I might have said yes to clean it out

But if you must clean it out and hell be damned,then id use (K1, kerosene, parfin) (all the same, differant name regionally)

Prop
Prop and the Blackhole Midget

erm. Where's the sludge come from in a box Prop? In engines it's combustion by-products in the oil. Only stuff hanging around that's horrid in a gearbox should be bits of gearbox rather than sludge; the bits might make a sort of tooth paste (not that sort!)

Rusty goo in the casing is a bad thing. Got a pic? Means something is rusty or has been inside - if it's teeth or bearings then a noisy gearbox is guaranteed.

In that situation I'd be jacking the car up at the back, empty box, fill with paraffin and run it WITH NO LOAD on it and at slow speed through the gears. Empty paraffin out and repeat till it runs clear; same as clearing out bits of mank after an exploded halfshaft.

Then refill with decent 20-50 engine oil as per spec.
Rob Armstrong

Rob,

The brown goo scares me... im guessing it may never have been changed...I do understand your comment about sludge in.engine and shouldnt be in the gear box, but if its already brown and paste...it may have well gone bad 35 years ago

Prop
Prop and the Blackhole Midget

Over the years, trans oil can get pretty nasty. I suspect from condensation of water. I went through this on my 46 Chev truck recently. I realized there was a problem when I could not move the gear lever on a cold morning. Hmm, not sure how that happened. I'm pretty sure I had just changed it in the mid-seventies.

I agree with the kerosene (paraffin) flush, though I would use diesel fuel since it is easier to get, cheaper, and probably has a bit better lubrication properties. However, when I use it to flush gearboxes, I add a quart of motor oil to 3 or 4 quarts of the diesel.

Then, like Rob said, run it with the drive wheels in the air. I do this in all gears to help spread the flush.

I think it is not normal to use synthetic in most gearboxes because it can be too slick for the syncros.

Charley
C R Huff

What gearbox is it exactly IM?
RS Hughes

Right I have decided not to flush the box.I will go for a half hour drive then remove the drain plug and see what comes out. When I refill it with 20 50 oil should I use ordinary engine oil or Valvoline racing oil,as both are available?
I.M. CHRISTIE

No sure about the diesel fuel advice as modern low sulphur diesel fuel has much lower lubricity than older fuels. I was told by an engineer I knew at LR that modern diesel fuels could result in pump failure of older models in a mater of months.
David Billington

This thread was discussed between 07/06/2015 and 09/06/2015

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