Merc finally crankin'

Firewood

Petty Officer 2nd Class
Joined
Jun 4, 2001
Messages
117
Well after rebuilding starter,and replacing both solenoids I have the ole beast turning over. In the mean time I had been changing fluids and such. So tonight I bought a brand new compression guage from sears.I removed all 4 plugs and just cranked it a bit. I wanted to fill the new oil filter. So I then hooked the guage up. Keep in mind its a 4cyl. Both exteriorpistons pumped out 170psi and the middle two 140-150psi. I squirted some 80w oil into the middle cylinders and didn't do much maybe 5 or 10 psi more. So i'm figuring leaky head gasket between those two? I also squirted some oil into the exterior cylinders and got 10 psi more out of those. The manual says 150 psi is normal...so it has me thinking. I think next I'm gonna get some fuel into it and get it running,warm it up and see what kind of results I get. This motor has sat 8 years or better, and tonight is the first action its seen that I know of. I'd like to hear a few opinions on my compression results. Ultamitly I have 20 psi difference amoung the 4 cylinders. Also I have the motor on a stand in my garage, I plan on rigging the garden hose to the raw water hose that comes from the lower unit. Water is gonna be shooting out the exhaust pipe!! Also what about back pressure on the exhaust, all I have on it is the riser/water resevior. Do I need to do anything to the exhaust besides point it out my garage door?!!LOL
 

norman158

Petty Officer 1st Class
Joined
Jun 29, 2001
Messages
329
Re: Merc finally crankin'

get her warm and check the comperssion again
 

manowar

Petty Officer 2nd Class
Joined
Jul 9, 2001
Messages
124
Re: Merc finally crankin'

you have to check compression with motor warm more exact readings do you have a good idle and do the rpms respond to throttle if you changed your idle setting you usally have to adjust your throttle settings
 

Firewood

Petty Officer 2nd Class
Joined
Jun 4, 2001
Messages
117
Re: Merc finally crankin'

Had sometime today to mess with the motor. Couldn't get spark..after chasing problems and such, It turned out to be a bad coil lead. So I picked up a new set of wires,cap,rotor,points,cond. Put the new wires on and she fired on one crank. I ran short on time and the wife was complaining about me not watchin' the little guy.Tommorrow I should have it warmed up and new compression readings.
 

Firewood

Petty Officer 2nd Class
Joined
Jun 4, 2001
Messages
117
Re: Merc finally crankin'

Well I'm happy to report all cylinders are identical @ 170psi. I got all the bugs worked out of the motor and she idles real good, I warmed it up , popped out the plugs and did another compression test - I was happy to see those results. The manual says 150psi for a reading, I'll take the 170. :)
 
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