Re: Engine Compression Test Help?

["Joe Costanzo" <joe_costanzo@domain.elided>]

     Mark,
     
     I believe the following is correct - any other digesters, feel free to 
     chime in with corrections.
     
     Disconnect the coil wire from the distributor.  One cylinder at a 
     time, remove the spark plug & thread in the fitting for the 
     compression tester.  Turn the key and crank the engine a few times.  
     Your compression reading should be on the dial.
     
     I was told yesterday (coincidence, huh?) by a coworker that to 
     determine whether it's bad rings or bad valves causing compression 
     loss, some engine oil (10W-40, etc. - just enough to coat the piston & 
     get down on the sides) into the combustion chamber before running the 
     compression check will temporarily seal up a bad compression ring.  
     I've never checked it myself, so I can't say for sure if it'll 
     actually work.  Remember that once you reinstall and run the engine, 
     this oil will cause extra smoke.  Also, if you put too much oil in, 
     you could possibly hydraulic the engine.
     
     Again - I've never actually tried this, so you might want to check 
     with someone more experienced.  Either way, I hope this information is 
     useful.  Good luck!
     
     Joe Costanzo
     '79 Scout II


______________________________ Reply Separator _________________________________
Subject: Engine Compression Test Help?
Author:  alice@domain.elided at internet
Date:    9/24/98 8:53 AM


Hello,
Can someone direct email me details on how to perform a proper 
engine compression test.  I want to do it this day, so direct email 
will help me most.
     
Specifically, I want to know whether this is performed cold or hot 
(warm) engine, carb throttle blocked open or closed (assuming choke 
plate is full open), spark plugs in or out, oil squirted in cylinders 
or not (and how much), how many cranks to allow,  etc....
     
How can I determine if a problem exists with the rings or valves 
or elsewhere?  What are the series of steps to determine a full 
account of the engine condition?
     
Thanks!   Mark