Originally Posted by
markk
So now a fool can do a compression test, and like I stated above, and thank you for backing me up, compression tests are pointless for diagnosis other than has it has it or differentiated amounts.
Whenever you post, you always come across trying to belittle people and their own experience/professionalism.
For your information I teach this to people day in and day out and spent over 20 years diagnosing and repairing engines.
Just to finish, and my apologies to the op for the off shoot, I did state the vehicle had a missfire and a cyl leak tester would have pinpointed the issue without fail, but then you knew that im sure.
Regards
Mark
And equally your leakdown test is pointless on its own. And as I said, you didnt say which cylinder had a misfire, nor give a clue as to whether it's fuel, spark or other misfire problem. The misfire could have been on a good compression cylinder which would have meant either a leakdown or compression numbers were actually pointless for your specific problem.
That doesnt mean a compression test is useless, if you're a teacher then you should know this.
A leakdown can only give a clue as to a valve or piston sealing problem. A compression test can give insight to more than that as it relies on also getting air into and out of the cylinder in order to give a result. So IMO in many cases is far more useful than a leakdown test.
In the case of the OP, a compression test sounds very valid, and the exact results will give a good diagnosis. Again, you say you teach this stuff, you should be very well aware of this.
And back to you claiming a leakdown can pinpoint a misfire. So how can a leakdown pinpoint a failing plug, lead, coil, dodgy injector, worn camshaft/valve clearances too large ?
All potential causes of a misfire, and none of which a leakdown test will identify
But I guess you knew that too ?