Volvo Penta 5.0 GL Compression Tolerances

[KrustiKrab]

Hi, I didn't use my boat last season and when I winterized my 2001 Monterey with a Volvo 5.0 GL had 85 psi on cyl # 5. I added Marvel Mystery oil in the oil when I changed it then directly in the cylinder right before I stored it. I just tuned it up and have it now at 140 psi so the issue appears to be a stuck valve. The others are between 150 & 160 averaging in the low 150's. Is this satisfactory ? Any suggestions?

Thanks

 

[Bondo]

Ayuh,..... Welcome Aboard,.... I'd run it 10, 20 hours, 'n retest it,...

 

[Scott Danforth]

Could be a sticking valve, crud on the valve, sticking rings, etc

As Bondo said, run it a while and retest