1978 merc compression test after sitting 8 years

stevehendo34

Petty Officer 3rd Class
Joined
Aug 7, 2010
Messages
92
Turns over, what should i do before taking compression check.

Have not bought it yet, $150 for motor and controls was set up for pontoon which I need.

I know how to check for spark and oil in lower unit and bent prop shaft.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
50,283
Pull plugs, squirt a bit of oil in the cylinders. Take compression, then rebuild carb
 

tommarvin

Ensign
Joined
Nov 22, 2015
Messages
999
Take all the plugs out, we have to ground our plug wires to block if you turn the key, what I just learned, you can do a compression with key off, and use a pull rope, you cant break anything this way, because you didn't buy it yet maybe.

How do you check for a bent prop shaft ?

They say all cylinders should be within 10psi.

Was there water in the LU, if so don't buy it. or low compression.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,102
Gee, if that motor is an inline 6. it will have a distributor. Ign parts for it are expensive. Anyway to check to see if it has spark?
 
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