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MG Midget and Sprite Technical - Rear main oil seal opinions

Over the winter I plan to pull my engine (1098 - small mains) and replace the clutch. Whilst out I'd like to have another go at reducing the amount of oil which finds it's way out so plan to carefully replace all engine gaskets. I've read some good things and bad things about the rear oil-seal upgrade kits that are available. Would welcome any opinions (good or bad).

Simon
SA Wood

I've always found crankcase vacuum fine to retain oil in engine...

A
Anthony Cutler

Currently no crankcase vacuum. Vented via standard pipe on tappet cover, vent on rocker cover to air filter and oil filler cap. Running single H4 SU carb through Shorrock supercharger with no vacuum attachment. I'd presuambly need a 1275 timing chain cover with canister/vent, HS4 carb ? - anything else ?
SA Wood

Further thought - not sure whether 1275 timing chain cover vent/canister will foul supercharger drive belts - anyone know ?
SA Wood

I used the mini-mania rear crank seal kit.
Pricey, and it took awhile to realy seal however virtualy leak free now.

http://www.spridgetmania.com/web/SUBTYPE/SearchText/CarSearch/SPRITE/Search/ric777/Search_Inventory.cfm
Phil Burke

Please mail me direct (my address: jed2'at'cam.ac.uk)
John.
J.E. Davies

Phil - wow that's expensive. In the uk, they are nearer £100 I think. Do you have crankcase vacuum or is your block open-vented like mine ?

Simon
SA Wood

They were slighty less expensive when I rebuilt in 2007.
I have crankcase vent. but added the seal anyway while I was in there.
As I say there are 'virtually' no leaks. I'm reluctant to say 'leak free' as I wouldn't want to pss off the gods of Mowog

So many parts are cheaper on your side that if I had the time and money to do a complete restoration at one time, I'd probably schedule a holiday to the UK before begining
Phil Burke

SA,

The crankcase seal wont cure all your ills, you will need to create some kind of negitive pressure inside the crankcase (aka vacume cleaner)...venting to atmosphere will only do so much manily at low rpm(drinking straw with no p/n pressure at both ends), once you bring the RMPs up to running speed, the engine it devolops pressure inside and pushes oil out every were it can (leaf blower) ... even if you run some tubing from the dip stick pipe to the intake manifold, thats better then nothing. ( thats vacume)

these engnes dont have a rear seal in the traditional sence...its a large screw that winds the oil back into the crankcase so thats the reason why vacume (neg. pressure) inside the crank case is so essential


prop
Prop

Tried umpteen lip seals,always wore Quickly and leaked a bucket,even before turbo fitted.Agree keep labyrinth,create crankcase vacuum.Anyway A series always marks where it's been-it's a sign of affection!
steve cowling

Like Phil, I installed the same kit when I rebuilt my engine. The seal does work, but only if there is a crankcase vacuum.
Stephen Strange

Thanks everyone for your comments. I will look at sorting out some crankcase vacuum. Fairly sure that canister on timing chain cover (as fitted to 1275) will foul supercharger drive belts. Anyone got a good unwanted SU-HS4 for sale ?

Simon
SA Wood

If you are willing to adopt an electric fuel pump, you can use the fuel pump hole for locating that canister, if your timing chain cover is too close.

Mini Spares sells an adapter for this purpose.

Your 1098 should already have a breather tube on the lifter cover that you can use, too.


Mr. Gasket sells a vacuum device that sucks from the exhaust pipe, for drag racing (the higher the RPM, the greater the vacuum). Sounds neat-o, may be over kill.

I have pondered the use of some kind of a diaper, or sanitary napkin just under that flywheel housing drain hole, to gather up those drips for me (I'd replace the pad, say, once a month!).

Also, most auto parts stores now sell a gray, fiber mat with poly backing that will absorb quite a lot of oil (I've seen them hold up to a quart). You just park over it and replace it when it gets too messy.


Norm
Norm Kerr

Norm,
you mean aa evacusump system, it works well above 1500rpm, i'll plumb it into the dizzy when the megajolts fitted.
Brad 1380

This thread was discussed between 13/08/2010 and 17/08/2010

MG Midget and Sprite Technical index

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