5.0 Merc Compression Readings

[New At This]

Hello, recently I purchased a 2000 boat that ran great at first, then I carried some fuel in. Started to bogg down, no top speed at all. Changed the cap, rotor, plugs, wires, fuel filter, no water in fuel. However, fuel seemed to lack that hi octane smell. Ran pretty good afterwards. Did a compression test and it registered 210 across the board. Is this considered good ?

 

[Lou C]

that's higher than normal, was there any sign of water in the cylinders?
that's a cause of high compression test results.
other causes of high compression test results on what's not a high compression engine:
faulty gauge
carbon build up in the combustion chambers
normal is about 150-170 or so. My old '88 4.3 is usually between 160-170.

 

[alldodge]

210 is way to high, either a bad gauge or there is liquid in the cylinders (gas,oil or water)

 

[New At This]

Seasoned mechanic did the plugs, wires compression check.

 

[alldodge]

Doesn't change my comment, motors that run on 87 octane do not have compression numbers that high. If motor was designed to run on 93 octane then could be right

 

[Scott Danforth]

If your motor truly has 210 psi cranking, it's a 13:1 drag racing motor

Mercruiser manual states cranking psi is 150 per cylinder

Seasoned mechanic did the plugs, wires compression check.

Is that BBQ seasoning or season salt? Because if the mechanic told you it was 210 psi, he/she is an idiot