Merc 700 Compression Test

[jschrift]

I am about to check the compression of my engine I am buiilding a stand for it and I am just planning to hook it up to a battery and crank it for a few seconds. Should I squirt some oil down in the cylinders? Or do I need to have gas or anything else hooked up to it when I do this? Do I need to keep the spark plugs in or out? And does it matter about the throttle? Full open? Closed?

Thanks

 

[jschrift]

Re: Merc 700 Compression Test

It is a 1978

 

[Chris1956]

Re: Merc 700 Compression Test

Normally you test the compression with theplugs removed, throttle open full , with no extra oil in the cylinders. If you use the gear shift to open the throttle, watch as you crank, as the prop will turn. Removing the prop is best. Use a jumper from the battery connection to the starter solenoid, to the non grounded small terminal on the starter solenoid's primary winding, to crank the motor.

 

[JUSTINTIME]

Re: Merc 700 Compression Test

the motor will not crank over if u put it in gear, because of the neutral safety switch

best way is get a remote starter to test and just open the throttles by hand
u also need a spark board, or pull the emergency stop switch