compsion test question

[foresteronw]

I am just wondering if anyone can point me in the right direction in performing a compresion test. I know how I need to hook up the guage, but in my manual it says to ground the coil wire. Any advice on how to do this, were the best place to ground it to would be. And how many tests should I run, as in should I do it three times and take the average or somethig different. Also does it matter weather I use the starter or should I crank it by hand? Thanks

 

[kenimpzoom]

Re: compsion test question

You have to crank it with the starter and make sure the battery is good.<br /><br />Just pull the coil wire off of the distributor and clamp it or alligator clip it to the engine block.<br /><br />I usually just take the readings twice and if the readings are the same or close move on to next cylinder.<br /><br />Also, be sure to warm up the engine first for about 10 minutes, and then ground coil wire, then open the throttle all the way, and then do the test.<br /><br />Ken

 

[foresteronw]

Re: compsion test question

Just curious about two things you said. Why do you open the throttle all the way? And I have been told that you can't truley warm up your engine in the drive way with the "muffs" will this be ok to run it there for ten minutes for a compresion test?

 

[kenimpzoom]

Re: compsion test question

Yes 10 minutes is fine on the muffs.<br /><br />You open the throttle all the way to let the engine breathe all the air it can breathe.<br /><br />If the throttle was closed, then engine wouldnt get enough air, and the compression would be low.<br /><br />Ken