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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - Valve stem oil seals

With the help of a MASC member, and his screw spring compressor and the 'Indian Rope Trick', I replaced the four 3 year old inlet valve oil seals on my 1275cc car for eight viton Mini MPI ones.

What a difference! From lots of smoke, especially on start up, the second round about from home or waiting to park at a drive in, to no visible smoke. I also do not smell of oil when I get out of the car and the car is genuinely running better.

Compared to a new standard black seal the ones removed are more rigid and the hole for the valve stem has enlarged, offering no resistance or sealing at all, despite the springs still being in place on them.

No sign of valve heat problems during high speed running, the tool was excellent and I was surprised how much rope was required.

Highly recommended.
KS Thompson

I'm not sure putting seals on the exhaust valve stems is recommended on all A series engines because the stems need a bit of lube due to the high temp the valve stems get to. It all depends on the materials the stem and valve guide are made of and maybe the later MPI minis were made from better material.
Rob
MG Moneypit

I have had excellent results with viton valve seals on all 8 stems on both the midget and the B. Reduces oil consumption to almost zero. 90K miles on the B engine with Viton seals and no issues whatsoever.
Glenn Mallory

I am not certain but I think earlier A Series engines had different stem seals to later engines. I think they were simple "O" rings similar to the earlier EXPAG engine. I made a mistake when rebuilding the engine from my TF and slipped the seals over the stems before fitting the springs etc. They should go in the spring cap under the collets. This prevents oil, that collects in the cap, running down the valve/ guide when the engine is stationary. Hence smoke on start up. When the engine is running any oil that is splashed on the valve stem is squeezed out as the valve moves down but a smear remains to lubricate. A common upgrade for the EXPAG is to fit Mini top hat seals but they need a groove machining in the guide (or as some do a drop of super glue) But there is a debate whether they stop lubrication.

Jan T
J Targosz

This thread was discussed on 15/09/2024

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.