Here is the question ,,Will testing one cylinder for preasure tell you that either the other 5 is about the same ? or could one cylinder be fine and another real bad? What are the odds of one cylinder being bad when the motor is not buring oil which would mean bad rings for example
Try testing compression on cylinder #1 when the #5 piston has a big hole in it. All the cylinders must be tested, and a percentage variation between them needs to be calculated. Compression tests in general are a very primitive way of monitoring the condition of the cylinders. A leakdown test where air pressure is introduced into the cylinder with the crankshaft locked is a much better indicator of the mechanical condition of the piston rings, valves, head gasket, etc. Depending on the skill of the operator and the testing procedure he uses, a compression test is sort of a "measure with a micrometer, mark with chalk, and cut with an ax" process. It's better than nothing, but not much. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Try testing compression on cylinder #1 when the #5 piston has a big hole in it. All the cylinders must be tested, and a percentage variation between them needs to be calculated. Compression tests in general are a very primitive way of monitoring the condition of the cylinders. A leakdown test where air pressure is introduced into the cylinder with the crankshaft locked is a much better indicator of the mechanical condition of the piston rings, valves, head gasket, etc. Depending on the skill of the operator and the testing procedure he uses, a compression test is sort of a "measure with a micrometer, mark with chalk, and cut with an ax" process. It's better than nothing, but not much. Jerry
This explains it very well .. I was curious and not needing to do it ,, thx Jerry
Gearhead, Moderator for The Swap Meet and General Truck Talk
idaho,
Just a chime in here in case you hadn't checked yet. Here is just a sample of many available "engine leak down tester" available (not mine nor can I vouch for if this one as a good value or not) at an inexpensive price should you decide to do the testing yourself:
Perhaps others will come along and add their wisdom???
See below pics for my "old school engine tester" found amongst the boxes of spare parts and tools I got along with my Grandfather's '51 many years ago.
Dan
Dan
1951 Chevy 3 window 3100 (My Grandpa's hunting truck) 1966 Chevelle (Wife's Hot Rod) 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) Com Fac Maint Lead Tech Retired (1998-2021)
Finally time to get to work on my Grandpa's (now mine) truck!
"Free" means you leave a theoretically refundable deposit equal to the value of the tester and get it back when the tool is returned. How accurate it might be depends on how badly it was abused by the last guy who used it. I don't know about anybody else, but I'm pretty selective about who uses my hand tools, let alone my precision test equipment. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Thx to all of you ,,,,,,,,,,,for the explaining of how one should test compression on an engine the correct way and also what tool and where to get one.. I was curious and now I know ,,and one day when I sell my old stove bolt Car I will use these great ideas here if needed ,or share it with the new owner.
