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Gearbox oil is foamy

Posted by isaacjames24 
isaacjames24 Avatar
Isaac C.
Olympia, WA, USA   usa

I just checked my gearbox oil level and it's foamy. Very foamy. So foamy it's reading far above the FULL mark on the stick. I just changed the oil in it to Valvoline VR-1 20w-50 (same as I use in my engine) about a month ago. I was talked into using Royal Purple previously and drove with it in there for a few months. I hated it and so did the gearbox! Don't do it!!
Anyway, the car sat out in the cold rain for the last week (long story) so I warmed it up for about 5 minutes and then checked the fluids before I went on a little cruise. That's when I found the frothy gearbox oil.
Thoughts on the subject?

MKulka Avatar
Matt Kulka
Charlotte, NC, USA   usa
1974 MG MGB "Sophie" ~ For Sale ! ~

Does it look like a milkshake? If so, that's moisture in the oil. Since it sat out in the cold and rain, I suspect it's condensation. I would take the car on a run, long enough to get it warm and stay warm for awhile - an hour maybe? Then check it again. I'll bet that allows the moisture to evaporate and the oil to come back to normal.

isaacjames24 Avatar
Isaac C.
Olympia, WA, USA   usa

Thanks Matt! Sounds logical to me. I was thinking it probably had something to do with it sitting outside. Looks like I'll have to go on a drive....strictly for the benefit of the car, of course! If only I could get my wife to believe that...

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ohlord Avatar
Rob C
North of Seattle, N.W., USA   usa
1971 MG MGB "Bedouin 2"

It is most likely overfilled after the fluid change. They are more prone to aeration if even a bit above the full line.



"You take off the roof and the top is the height of the nearest Star"

ingoldsb Avatar
Terry Ingoldsby
Calgary, Alberta, Canada   can
1971 MG MGB

If it is above the fill mark, then I suspect it is being beaten into a froth by the gears.

I would change it (and I would go to a GL-4 gear oil such as Redline MT90) and check the level carefully.



Terry Ingoldsby
terry.ingoldsby@DCExperts.com

ohlord Avatar
Rob C
North of Seattle, N.W., USA   usa
1971 MG MGB "Bedouin 2"

Castrol 20/50 wt



"You take off the roof and the top is the height of the nearest Star"

rdgreen Avatar
Robert Green
Adelaide, South Australia, Australia   aus

Here we go!!!!



Those who risk nothing, do nothing, achieve nothing, become nothing.

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isaacjames24 Avatar
Isaac C.
Olympia, WA, USA   usa

You guys are welcome to discuss fluids-types all you want smileys with beer But the foam has settled and the fluid level is a gnat hair below FULL. I'm off for a drive!

mimssandi Avatar
Roger & Sandra Hobart
Mims, Fla, USA   usa

Water can get into the tranny from the shift lever area. Leave it in the rain with the top down and water runs down the shifter and finds its way into the tranny. Light brown foam is water.

GILMGA Avatar
Gil Dupre
CHATTANOOTA, TENNESSEE, USA   usa
1962 MG MGA
1974 MG MGB GT

Maybe you should use non detergent oil.devil smiley



Gil

gooser Avatar
Drake Myers
Danville Va, USA   usa

In reply to # 2306145 by GILMGA Maybe you should use non detergent oil.devil smiley


x2.

dipstick Avatar
Kenny Snyder
La Center, Washington, USA   usa

Consider checking the gearbox breather cap to be sure that it is clear to vent.

I doubt that rain water would get into your GT transmission, unless you leave the sunroof open.

Transmission oil hot generally runs 250 - 275 degrees (put your hand on it if you don't believe) and any moisture will boil off and pass out thru the vent.

The MGA/MGB transmission gears are designed to throw off mass quantities of oil in order to get that oil into the upper channel on the left side of the inner case that feeds the front cover, thus there will always be some "foam" on the dipstick on hot shutdown.



Be safe out there.
Kenny

MCCT Avatar
Charles Tisdall
New Zealand, Auckland, New Zealand   nzl
1967 MG MGB
1974 MG MGB GT

quite a common issue..I replaced my oil with Penrite non detergent ..made big difference

GILMGA Avatar
Gil Dupre
CHATTANOOTA, TENNESSEE, USA   usa
1962 MG MGA
1974 MG MGB GT

Ha. Non detergent oil doesnt foam.



Gil

Wachtmans Avatar
Wouter Strodijk
OVERVEEN, Noord Holland, Netherlands   nld
1974 MG MGB "The Bee"
1974 MG MGB "The Bee"
1974 MG MGB MkIII "The Bee"

A descent quality oil does not foam! It is water that makes it foam. Water cannot enter the tranny; even when you leave the sunroof open, water cannot run down the shifter into the tranny, that's BS; there is no opening whatsoever to the tranny over there! It could be either the Royal Purple does not match with the oil you replaced it with, or your oilcan has collected water. Don't run your MG until you get the clue! It will ruin your gearbox.

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