MT82 Gearbox overfill ??

[Robmacca]

Guys... I have a 2010 Puma 110 and I’ve recently changed the gearbox oil. The manual indicates that it holds 2.4ltrs but I’ve read somewhere that u only put in 2.2ltrs.
I ended up putting in 2.3ltrs after speaking with MR Auto who actually put 2.5ltrs in. There was no oil coming out the fill plug when I was finished.
Now after a full days drive I seem to have a leak out of the drain opening where the Gearbox and TC bolt together.
I’ve checked the gearbox level and when I remove the plug the oil seems to overflow.
What sort of damage can be caused to the gearbox from overfilling the Gearbox?
Should I let the excess oil flow out the filler plug?

[ozy013]

Initial factory fill is 2.4ltrs, service fill is 2.2ltrs. The fill plug is not a level indicator...However I shouldn't think 0.1 or 0.2 of a ltr should cause any damage. If your worried just drain it and refill with the correct amount. An excessively overfilled gearbox can cause extra internal pressure build up which can damage seals. Also if the gears are completely immersed in oil it can cause foaming which affects the lubrication of the gears.
If its any consolation when I first changed my gearbox oil at 80,000ks I got just under 3ltrs out of it. I'm assuming by the colour and smell of the oil that it hadn't been changed since factory.

[350RRC]

Initial factory fill is 2.4ltrs, service fill is 2.2ltrs. The fill plug is not a level indicator...However I shouldn't think 0.1 or 0.2 of a ltr should cause any damage. If your worried just drain it and refill with the correct amount. An excessively overfilled gearbox can cause extra internal pressure build up which can damage seals. Also if the gears are completely immersed in oil it can cause foaming which affects the lubrication of the gears.
If its any consolation when I first changed my gearbox oil at 80,000ks I got just under 3ltrs out of it. I'm assuming by the colour and smell of the oil that it hadn't been changed since factory.

Older RRC's are 'classic' for diff overfills. The level plug originally used to be in in the cast part that holds the bearings and gears. Fill (from the fill hole in the sheet metal part) till it reaches the bottom of the thread in the level hole.

On later diffs the level plug was deleted in the cast part and some people just assumed that the fill plug in the sheet metal part was also the level and end up putting an extra 50% more oil into the diff than specified.

I only got caught out once by this and it took awhile to figure out what was going on. These days I just put the right amount into the Hills garden sprayer with modded wand, pump it up and fill via fill plug. One diff on my POS has the level plug, the other doesn't.

I do the same with the TC.

DL