ok mr mechanics, ive searched the threads about why my car may be smoking and read many suggestions to do a leak down test to test cylinders. how exactally do i do this? i want to eliminate possible causes of my smoking problem before i tear into something i dont have too.

 

A leak-down test requires an air supply, a regulator, and a calibrated orifice to meter the air into the cylinder. Pressure gauges are installed in the assembly before and after the orifice. Engine is restrained from turning and air is directed into the cylinder w/ pressure upstream of orifice regulated to 100 psi. Depending on the amount of air leaking by the piston or valves, the pressure will drop across the orifice, so you might read 96 psi downstream of the orifice for a good engine reading. The reading is usually written as 96/100. A low reading, say 70/100 would indicate significant air leaking somewhere. You can listen at the exhaust pipe for leakage by exhaust valve, listen at intake manifold for an intake valve leak, or listen at the crankcase for piston/rings leak.

A leak-down test is more definitive than a simple compression test in assessing leakage by the rings and there are usually standards available to guide you on the meaning of the leak down readings.

The equipment is frequently available on ebay for auction and is readily available from tool stores online.

See following link:

http://www.racerpartswholesale.com/long29a.htm

good luck

 

OK Mr. Spock