Engine blueprinted Sept 1990. Less than 5000 miles since (very infrequent usage, probably the cause of my problem.) #5 wet with oil, compression 15 points less than other cylinders, smoking left exhaust. Suspect a cracked ring or bad intake guide. Is there any way to differentiate without pulling the head?

Also, need recommendations for a reputable 4.2 E-Type mechanic in the Tucson area.

Appreciate any and all comments.

Jerry

Submitted by ianc@uvic.ca on Sun, 12/31/2006 - 15:24

Putting a couple of cc's of oil in the suspect cylinder works fine. Heavy is better. (DON'T use 20-50: it's only 20 at low temps. Get some straight 40 wt.) Make sure the throttle is wide open. 1969 E Type

Submitted by DShali20@opton… on Wed, 12/20/2006 - 11:23

I've been told that if you pour a small amount of oil into the cylander thru the spark plug opening it will temporarally seal bad rings. If you then perform the compression test and you have good compression it indicates ring failure. If you have poor compression, it indicates valve guide failure.

This is something you can try if you don't have the equipment for the leak down test.

If you try it, let me know. I've never done this test.

Submitted by mfrank@westnet.com on Sat, 12/09/2006 - 21:55

What you need to do is a leak down test. Any place that does engine service should have the equipment. Basically, you crank the questionable cylinder to a point where both valves are closed. You install the tester in the spark plug hole. The tester is a brass manifold, with a schraeder valve, a hose, and a pressure guage. Using the fittings on the manifold, you fill the cylinder with pressurized air, and observe how long the cylinder can hold pressure. If there's a leak, it will be apparent. You will also be able to listen at the carbs, exhaust, and oil fill hole and will be able to pinpoint the problem by where you hear the air escaping.

The combinantion of low compression and oily plug suggests a ring more than a valve guide.