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MG Midget and Sprite Technical - Crankcase venting and rear oil seal

I'm pulling my engine out for a transmission swap and I'm going to convert to the rear crank seal from moss to hopefully stop a slow oil leak that wont go away. I have a 1972 midget 1275 but have older carbs so I have a PCV valve on the manifold instead of the Y-tube to the carbs. Yes I know this is incorrect for 1972.

After adding the oil seal will I be able to ditch the PCV setup? Will I get "green" credits towards venting to the atmosphere if I stop marking my territory with 22w50?
CJCharvet

CJ,
I'm glad to hear you found a Datsun tranny.
I put the MiniMania seal kit on my engine when I totaly rebuilt it a year ago. I still have some oil leaking.
The Rivergate kit now employs a seal kit that is "supposed" to work better, so why add the Moss kit?
I'm not even sure if you can do both.
I'm running the Y-tube and have emptied the "wool" from the front cover can, so I'm not sure if you can ever teach these old motors new tricks such as not marking there spots.
Phil '5 speed sitting on garage shelf'
Phil Burke

NO YOU CANT!!!

The engine does not have a oil seal by its nature, because of wear in the piston rings you have blow by resulting in positive pressure meaning "OIL LEAKS",

What you want is negitive crankcase pressure thus the hose from the crankcase to the carbs which sucks air pressure out making a vacume and holding the oil inside the engine (IN Theory)

If you vent to atmosphere, it will not create the vacume and you will have 1:1 aymosher inside and outside the engine, meaning no vacume and you will have 3x as much oil leakage,

Good luck on the tranny conversion
prop
Prop***The End in 2012

CJ-
It is important to retain the crankcase ventilation system. Properly maintained, crankcase gases are drawn into the combustion chambers of the engine by the vacuum created by the fuel induction system. This permits the crankcase to function in a partial vacuum of about -2 PSI which not only reduces power loss due to the pistons, connecting rods, and crankshaft forcing the atmosphere inside of the crankcase to move about (a condition that is technically termed either ‘Windage Loss’ or ‘Pumping Loss’), it also causes oil mist inside of the crankcase to condense more rapidly while being drawn upwards towards the camshaft and tappets. Because the oil mist becomes more quickly and more highly condensed in the partial vacuum, more of it tends to fall into the sump rather than remaining in suspension as a fine mist and being drawn into the induction system. An oil separator that works on the turbulence principle is incorporated into the design in order to assist in preventing this. Due to the fact that the effectiveness of the system is dependent upon vacuum, all connections between the fuel tank, the vapor separator, the carbon canister, the rocker arm cover and its oil filler cap, the dipstick, the distributor, as well as between the oil separator and the induction system, must be well sealed in order to maintain the optimum state of vacuum.
J Strange

Prop,
He is adding a "real" seal. I do agree that you still want a slight negative pressure in the crankcase.

CJ,
I would suggest that you read the blurb on this at Barney Gaylord's MGA site, starting at
http://www.mgaguru.com/mgtech/engine/cv101.htm
and the following few pages.
David "just venting here" Lieb
David Lieb

Whoa you guys remember everything. I actually have postponed my search for a datsun transmission and I am going to use a spare a ribcase and rebuild the original. I've decided to add the moss oil seal while I'm at it. If the seal does anything, it should stop the small leak I've got. I will replace the PCV valve for now and shop for some y-tube carbs (I really hate the PCV valve). Thanks everybody.
CJCharvet

This thread was discussed between 11/01/2009 and 12/01/2009

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