1991 Mercury Black Max 150 compression question..

[TampaBoater]

Ok so I am looking at a 1991 Searay 180 Bowrider with a 1991 Mercury Black Max 150. Looks, great, fires right up, sounds beautiful. Did a compression test and its running even at 60psi on all 6. My question is, is this kind of low for this size engine? Spark plugs look almost brand new after sitting "supposedly" for 2 years. Carbs look great, like new quicksilver prop, kicks in forw/rev real smooth. I am just concerned about the compression and a water trial is not possible. Any thoughts?

Also, the steering is hydraulic, and when I turn the wheel its really loose and motor dont turn. There is a reservoir on top of the steering wheel base and its empty. Is this the culprit?

 

[sam am I]

"Water test not possible"............LMAO, wonder why? I'd give um $100 for the motor tho

From merc manual for these engines....

"All Models: Using a fully charged battery, throttle shutters wide open and cylinder block warm"

"110 - 135 psi, Variance between cylinders should not exceed 15 psi"

I'd maybe go 80-90 psi tops for a 91 but no less. If that gauge is correct, the guts have been ran out of it, it's smooth only because it's even across all the holes, its a dog...........Run like he!!!

 

[Iceman66]

Would try with another gauge,60 psi is way to low, but since they are the same I guess the gauge is incorrect.


" Also, the steering is hydraulic, and when I turn the wheel its really loose and motor dont turn. There is a reservoir on top of the steering wheel base and its empty. Is this the culprit?"

Probably, the question you should ask your self and the seller, is why.