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MG MGB Technical - MGB Sumps

According to Moss, there are three different MGB sumps.

18G-GA 12H395

18GB-18V797 12H1976

From 18V797 12H3541

I know that some sumps have the drain plug on the side, rather than at the corner, but does anyone know the differences between the three and how interchangeable they are?
Dave O'Neill 2

I'm surprised you've not already looked on Paul's site - http://www.mgb-stuff.org.uk/enginetext.htm#dipstick
Nigel Atkins

The 18G-GA sump has a different bolt pattern and is not interchangeable with later engines.

The 18GB & 18V sumps are interchangeable - the cut away corner sump on later engines was so that you can access the torque converter bolts through the hole in the backplate.

Chris at Octarine Services

Nigel

I did look at Paul’s site, but I didn’t see ‘sump’ in the engine index.

Chris

Did the 18GB sump have the drain plug on the side, or the corner?

I have a 3-bearing engine which has a leaking sump. I also have several ‘spare’ sumps, so I essentially need to identify which, if any, will fit. I’m not currently in a position to turn the engine upside down to check the bolt pattern.
Dave O'Neill 2

18GB plug on the side.

Only a 3 bearing 18G/GA sump will fit yours.

If you look at the top flange of the sump where the side bulges out, the 5 bearing sump has 2 holes in line with each other, the early sump has three placed on the curve.

The pic is the late sump

Chris at Octarine Services

and this is the bolt pattern for the early 3 bearing sump

Early sump = 19 holes, late sump = 18 holes.

Chris at Octarine Services

"access the torque converter bolts through the hole in the backplate"

Is that the large hole with the rubber bung as in the attached? I wondered why that was there.

paulh4

Yes - it allows you to get a 1/2 af cranked ring spanner in to undo the 4 bolts holding the torque converter to the drive plate.
Chris at Octarine Services

Incidentally only Moss seem to give 12H1976 as the earlier 5-bearing sump. Other suppliers say 12H1426, changing to 12H3541 about a year after the auto option arrived with the Mk2. That had long gone by the time of the 18V797 that Moss give as the change point.
paulh4

Moss are wrong!

I think all 18G engines had the full sump and it was the 18V that introduced the cutaway corner, but without Clausager to hand I can't be sure.
Chris at Octarine Services

I stand corrected - Clausager says the 18GD, but I have never seen one, in the UK I have only seen the GB & GG engines.
Chris at Octarine Services

Somewhere a long time ago and I can't find it now I read that the later 5-bearing sump came in with the 18GG engine, which was about a year after the auto option and the 18GD engine - quite possible and only changed with experience. The Leyland Parts catalogue only gives the later sump for all 5-bearing engines i.e. 18GB on, as do various suppliers, none (that I can find with Google) showing the earlier one. I can't see a specific reference to the sump in Clausager, and this http://www.mgbmga.com/tech/mgb17.htm states the earlier sump was used up to 18GK and the later only with 18V. FWIW.
paulh4

It has to have come in with the introduction of the auto option which Clausager says was with the GD. There is no way to fit the toque converter without that access.

Of course that doesn't mean that the earlier sump was not fitted afterwards - there is no need for the cutout on manual gearbox equipped engines.
Chris at Octarine Services

Thanks for all the information.

The one sump that I have to hand at the moment has the drain plug on the side, but only eighteen holes, so no good for a 3-bearing.

I will have to dig out some more.

At least I know what Iooking for, now.
Dave O'Neill 2

This thread was discussed between 05/06/2019 and 06/06/2019

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