The Ford Barn

Rich Bowes · 08-23-2015, 03:35 PM

Yesterday a friend and I conducted a series of diagnostic checks to see what work the motor in my '30 Roadster needs. Currently the engine is using some oil, as seen on the dipstick as the oil level decreases, and a puff of blue smoke from the exhaust pipe during gear shifts. Here are the results of the tests:

Leak down test results(conducted on cool engine, starting with each cylinder in turn at TDC, verified with digital inspection camera, then pumping 20 PSI into each cylinder in turn):

#1 cylinder -0 % leakage;

#2 cylinder - 20 % leakage, piston pushed down and engine turned backwards, air coming out the carburetor;

#3 cylinder - initially less than 3 % leakage, with air coming out exhaust pipe, then the leakwent down to 0 %;

#4 cylinder - less than 5 % leakage, piston went down and engine turned forward, could not detect where air was leaking from, checked carburetor, exhaust pipe, and radiator.

Camera also revealed carbon buildup atop pistons, and around the edges of some of the valves.

Vacuum test results (conducted on warm engine):

Drifts rapidly at idle between 13 and 20, stabilizes at higher RPM between 18 and 20.

Compression test results (conducted on warm engine):

DryWet

#1 cylinder -6060

#2 cylinder -6060

#3 cylinder6063

#4 cylinder6060

The leak down and vacuum tests indicate to us that the engine needs a valve job.

The oil usage, and blue smoke indicate oil in the cylinders, but that is not indicated by the compression tests, except maybe in cylinder #3.

Also, we don't know why the leak down test caused the piston in #2 cylinder
to go down and turn the engine backward, or why it caused the piston in #4
cylinder to go down and turn the engine forward.

Could someone please help us understand the test results, and let us know if they indicate that the engine needs more than just a valve job?

08-23-2015, 03:35 PM	#1
Rich Bowes Member Join Date: Nov 2012 Location: Cotuit MA Posts: 32	Questions for engine experts Yesterday a friend and I conducted a series of diagnostic checks to see what work the motor in my '30 Roadster needs. Currently the engine is using some oil, as seen on the dipstick as the oil level decreases, and a puff of blue smoke from the exhaust pipe during gear shifts. Here are the results of the tests: Leak down test results(conducted on cool engine, starting with each cylinder in turn at TDC, verified with digital inspection camera, then pumping 20 PSI into each cylinder in turn): #1 cylinder -0 % leakage; #2 cylinder - 20 % leakage, piston pushed down and engine turned backwards, air coming out the carburetor; #3 cylinder - initially less than 3 % leakage, with air coming out exhaust pipe, then the leakwent down to 0 %; #4 cylinder - less than 5 % leakage, piston went down and engine turned forward, could not detect where air was leaking from, checked carburetor, exhaust pipe, and radiator. Camera also revealed carbon buildup atop pistons, and around the edges of some of the valves. Vacuum test results (conducted on warm engine): Drifts rapidly at idle between 13 and 20, stabilizes at higher RPM between 18 and 20. Compression test results (conducted on warm engine): DryWet #1 cylinder -6060 #2 cylinder -6060 #3 cylinder6063 #4 cylinder6060 The leak down and vacuum tests indicate to us that the engine needs a valve job. The oil usage, and blue smoke indicate oil in the cylinders, but that is not indicated by the compression tests, except maybe in cylinder #3. Also, we don't know why the leak down test caused the piston in #2 cylinder to go down and turn the engine backward, or why it caused the piston in #4 cylinder to go down and turn the engine forward. Could someone please help us understand the test results, and let us know if they indicate that the engine needs more than just a valve job?