96 75 Force

[JCovas]

I have a 75 hp Force that has too much compression when the plugs are in to turn the motor. So far I've only found a single reed cracked. I replaced the cracked red assembly and removed head cover and lower engine cover also. I couldn't find anything unusual, everything actually looked great! It turned freely by hand and pistons were clean.
I assembled everything and I can't hardly turn the flywheel by hand or with the starter sunless I remove all 3 plugs. Does this engine have a preasure release?

 

[racerone]

Take the electric starter apart for inspection.----Have your battery load tested too.------No such thing as ---" too much compression "------Or post your compression numbers when tested with a good compression testing device.

 

[JCovas]

Something could be wrong with the battery and also with the starter but there is nothing wrong with my arms and hands. This thing ain't turning.

 

[jerryjerry05]

If it turns with out the plugs?
But doesn't when they're in?
Low compression on one or more cyl. all 3 should read within 5# of each other.
Do like racerone suggested, compression test.
Use a "good" tester, Harbor Freight tools give horrible results.
Then load test the battery, it can read 12v and still be bad??
Clean/rebuild the starter.
The battery cable could have a bad spot?

Some cases the lower unit gears/bearings go bad and cause hard turning, drop the lower if the comp
or other suggestions don't fix.

 

[JCovas]

Lower unit is off, starter is good and battery has been load tested. Does anyone know if this thing has a preasure release? I don't want to press the flywheel off and pull the crankshaft to then find out it doesn't have one.

 

[The Force power]

I don't know your motor, but in the link you can look up your motor and see if it does.

https://www.mercurymarine.com/en/ca/parts-and-accessories/parts-catalog

 

[racerone]

Was this motor possibly submerged at one time ?-----There is no compression release.----Do some orderly trouble shooting.----This should be easy to figure out !

 

[JCovas]

Never submerged...

 

[jerryjerry05]

What are the compression readings??

You say the starter's good even a NEW starter can be bad,and the battery's good and the lower unit is off.
If the comp is good???? then you might have a bearing seized on the top of the crank?
Post comp readings?