Ruling Out A Blown Engine Gasket

When all the symptoms point towards a blown head gasket, like loss of power and backfiring, try this quick and easy way to confirm the diagnosis.  First, you will need to take out all the spark plugs.  Next, take a section of paper towel, roll it up and push it into the removed spark plug hole.  When you have all the spark plug holes plugged with paper towel, roll the engine over and see if the entire paper towel is blown out of the spark plug holes.  The paper towel that remains in the hole will indicate a loss of compression in that cylinder.  The loss of compression will keep the gas from firing and force the raw gas into the exhaust pipe.  That will cause backfiring and a loss of power.

If a blown head gasket is indicated, it is time to take the engine head off and replace the head gasket.  Once that is completed and the head is back on and tightened to 55 foot-pounds, it is time to recheck the timing of your car.  A nice tool to use to get the first cylinder piston to top dead center for timing the car is one available from Eastwood.  It is called the “Whistler” and is part #46048.  Once you have this tool, you will need to make an adapter so that 18 mm will fit into the Model A spark plug hole.  The way it works is as the piston rises, compressed air escapes through the whistle.  When the whistling stops, the piston is at top dead center.  Then you can set your distributor to the first pole and the car should be timed.  Good luck and I hope this little technique helps you solve your engine problems.

This tech tip was provided by Jeff Johnson and printed in the September 2003 “A” Quail Call.

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