At 02:33 PM 4/8/02 -0500, Scott Willis wrote:
>My MGA is leaking between the transmission bellhousing and the rear of the
>engine from what I can tell. It's dripping off that seam. The transmission
>oil is not leaking. .... What could be leaking back there? ....
>
>Could oil be coming from the bushing on the back of the crank shaft? If
>so, wouldn't that make my clutch slip? I know I'll have to pull the motor
>to repair the leak so I want to order the right seals.
All things being relative, if it's not leaking too bad it may be
normal. The MGA doe not have a rear crankshaft seal. It does have a
mechanical scroll groove in the crankshaft that fits up very close to the
rear of the engine block and rear main bearing cap. This does a pretty
good job of keeping the oil in when the engine is runing, then allows a few
drops to dribble out when you shut it off. Keep in mind that this is a
1950's vintage car that was built with 1920's technology.
There is a gasket between the engine block and the engine rear plate. This
primarily keeps the oil in at the back end of the camshaft and has nothing
to do with sealing the crankshaft. The engine rear plate actually has a
slot in the front surface to allow such oil leakage to drain down the front
side of the plate, but some of always gets to the back side of the plate
inside of the bellhousing anyway. There is also a small hole in the bottom
of the bellhousing that should have a cotter pin in it ("split pin" to the
English blokes). This is a designed leakage point. The cotter pin is
supposed to vibrate about when the engine is running to keep the drain hole
clear so the oil does not accumelate inside the bellhousing.
On the other hand, if the leakage from the rear of the engine is really bad
(puddle every time you stop), then the engine may have damaged surfaces on
the scroll area of the crankshaft and/or on the close mating surfaces of
the engine block and rear main bearing cap. This can happen if the main
bearing gets badly worn to the point that the crankshaft can actually touch
the block or bearing cap. The proper cure for this condition is
particularly expensive, requiring complete disassembly of the engine for
shaving down the main bearing caps and line boring of the main bearing
cradles in the engine block (and maybe welding of the dameged rear surfaces
first). I once encountered this condition right after an expensive engine
overhaul. Not wanting to tear it all apart for more machine work, I
conjured up a devious rubber seal for the rear of the 3-main-bearing
engine. This is not particularly easy, but it can be much cheaper than
tearing the engine apert for more machining. Check here:
http://www.ntsource.com/~barneymg/mgtech/engine/rs101.htm
>Also, any clue as to getting the tappet covers not to leak?
Blue RTV sealant on both sides of the gaskets, and another dab around the
bolt head, should affect a perfect seal on the tappet covers.
Barney Gaylord
1958 MGA with an attitude
http://www.ntsource.com/~barneymg
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