What is this bung in the engine block for?

[Robert 352]

Can someone tell me what this bung is for which is sitting on the side of the engine block, immediately above the brass bung which is used to drain the block?

Was this fitted in the factory or has it been fitted after the car in which the engine sits was sold?

Robert

[dursley92]

All the blocks have that, probably something to do with the production process.
The small one below it is the drain plug.

[Robert 352]

I asked because I have not seen this bung before. I have half a dozen engines sitting here and this is the first block I have seen with this bung fitted. It is off one of the last Sprints imported into this country.

This particular engine which I am working on came out of a car which was owned by someone whose background was in electrics/electronics and which was fitted with sensors in various positions on the inlet manifold, in the sump and on the drive train. Was I wondered this part of his adaption?

My parts book does not show it.

Robert

[soe8m]

Early and late engine differences. This you see mainly at early engines. Some have only the small and some none. It's not a home made modification but std factory.

Jeroen

[dursley92]

Just looked at my spare blocks again, a couple have it and a couple don't.

This one is an Issue 17 and has the plug.

[MIG Wielder]

This is an interesting question. My 1850 only has the brass water-drain bolt. I did look at the early 1850 parts book and both the brass and the large cast plug are both shown. Up to WF 3852 the brass plug had a drain tap in it which looks very similar to the early MGB radiator drain. After that a plain brass plug is fitted.( 129077) The large plug is fitted up to WF 4272. ( 154395 ). Note the typo on the part number listing is a " WF " number.

Both plugs appear in the latest Dolomite parts book Sept; 1981
So yes, there was a period when only the brass plug was fitted.
And no, I'm sorry to say I still don't know what is behind the large one.
Tony.