merc compression test steps question

krawczmwk

Seaman Apprentice
Joined
Mar 17, 2010
Messages
41
I have a 1985 merc 50 hp 4 cyl outboard.
I bought a compression tester today. My question, I have read many posts on how to do a compression check and there seem to be many different ways to do one. I will list the steps I am going to take and if you wouldn't mind, check to see if I missed a step.

1. Warm engine
2. pull all of the wires from the 4 plugs
3. attach the guage to the first plug
4. ground the other 3 plug wires
5. in neutral, put throttle in wot
6. try to start the motor for 3 seconds, record the pressure
7. run the same test on the other 3 cylinders and record the pressure
8. check for pressure to be at least 100 and consistent across the 4 cylinders.

Does this sound right?
Thanks
mark
 

Barnacle_Bill

Admiral
Joined
Feb 8, 2004
Messages
6,469
Re: merc compression test steps question

I would trip the emergency kill switch. Then you wouldn't have to worry about grounding the other leads. Let the motor keep turning over until the gauge stops rising.
 
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