Re: Oil fill tube

Posted by Marco on August 14, 1998 at 00:08:44

In Reply to: Oil fill tube
posted by Al Downs on August 13, 1998 at 22:38:24

As Joe stated, this is a common problem with Model A's.Special breather caps with a tube to drain the oil to the bottom of the car began appearing almost as early as the "A" itself.
The cause of the problem is compression pressure escaping past the piston rings into the crank case. this is otherwise known as blow-by (or blowback as Joe said).With a properly rebuilt engine this situation should subside in 200-800 miles as the piston rings become seated.It will reappear as the cylinders and rings become worn (or damaged).
In many cases however, piston rings are installed with excessive ring end gaps which allows for some degree of excessive blow-by for the life of the engine.Many (most?)rebuilders either rely on the integrity of the ring manufacturer or merely check them to be sure the end gap is not to small.To small of a ring gap can cause cylinder scoring (leading to blow-by!), or other problems.
If you need a short term solution while the engine gets broken in then consider simply wrapping a shop rag or wash cloth around the tube just below the cap.Fold the rag in half with the fold up, wrap it, then circle it once with masking tape to hold it tight.Don't push it to tight against the cap or you will increase the crank case pressure and force oil out elsware.The rag will pick up 95% of the oil.

Follow Ups:
Re: Oil fill tube Kevin Daly August 14, 1998 at 07:05:04(1)
Re: Oil fill tube Marco August 15, 1998 at 09:57:12(0)

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