Checking Compression

[FreeBeeTony]

In order to check compression.......would I remove the coil wire off a 5.7L Mercruiser and pull one plug at a time?<br /><br />I don't know what type of ignition it has.....I think the engine is a 350 Magnum.<br /><br />I don't want to damage anything by pulling the coil wire.

 

[tommays]

Re: Checking Compression

you should be able to just pull the saftey lanyard and shut off the ingition system <br /><br />and then test away<br /><br /><br />tommays

 

[FreeBeeTony]

Re: Checking Compression

Would pulling the coil wire damage anything?<br /><br />Just in case it doesn't have a safety lanyard.

 

[a.d.mobile]

Re: Checking Compression

be sure to ground it out. pull all plugs open throttle all the way, when you do it closed the choke will be closed and allow fuel to be pulled in washing out the cylinders causing false pressure readings. a.d.

 

[jeff13601]

Re: Checking Compression

Also I believe you use only four compression strokes of the cylinder. Don S put in a link a couple weeks back that explains it thoroughly. It would be worth your time to read it it http://www.boatfix.com/merc/Bullet/97/97_25.pdf

 

[waterone1@aol.com]

Re: Checking Compression

The above is good advice. The three important issues are to disable the ignition, open the throttle and remove all spark plugs. Even with all plugs removed, I usually stop for a coffee break after 4 cylinders to give the starter a chance to cool down.