How to check compression

[Little.desperado]

Hi Everybody,

i heard, when checking Compression i have to make a connection between the spark plug wire and the engine, in order not to damage the ignition system.
Is this correct and absolutely necessary?

How can I easily make a connection between the spark plug wire and the engine ground?

Thanks for your held and advise!

Greetings from Munich - Oktoberfest-Time!!!!

 

[Scaaty]

Re: How to check compression

I would do it with ANY electronic Ignition parts, just to be safe. Easiest way is a jumper wire/clips from the coil wire to ground on say V-6/8's Auto motors, outboards same if you can get the right wire, or just whip up some clips and wire and do the individual plugs. You will still get a spark, so watch for gas fumes...

 

[Paul Moir]

Re: How to check compression

It is not necessary if the engine is equipped with a kill switch lanyard, or you have some other way to disable spark. For example you can leave the keyswitch on "off" and jump the solenoid with a jumper cable. (I hope that makes some sense!)

Otherwise, I simply leave the spark plugs plugged in and lay them against the engine, keeping them good and far away from the spark plug hole. This will not work if the engine is well painted though.

 

[rickdb1boat]

Re: How to check compression

A strand of wire with some large alligator clips attached works well for multi-cylinder engines....

 

[Bruce San]

Re: How to check compression

NAPA has a nice little rig for this. It's nothing more than a plastic handle with a spring loaded push button switch and two wires with alligator clips on them. about $12 I think. You hook it up right at the starrter solinoid and it allows you to engage and run the starter without the ignition circuit. Leave the key off and don't worry about the spark. It also allows you to stay with the compression tester not walking back and forth from the engine to the ignition switch. Makes a compression check on a multi cylinder engine much easier.