I recently purchased a 20' '69 Fiberform Spokane model with a Volvo aq175a 6cyl engine. Boat was sold by a friend of the widow of the owner so I didn't get much info on the engine. I do know that it is not the original and has been in the boat for several years.<br /><br />Engine runs strong, starts fine when cold. Oil pressure after warm up is a third of the way into the green on a gauge that goes to 80psi but has no other number than 0. At idle the pressure drops into the red after running at cruising speed (3500-3800rpms). Possible problems?<br /><br />I checked the compression in all cyl and came up with all but one in the 150-130 range and cyl #3 at 50, this is definetely a concern but I'm hoping to make it through the rest of the summer before tearing into the engine. Rings or stuck valve for the low compression, what else?<br /><br />Any other info some of you may have about this engine would be great, I need to decide today about what repair manual to get Clymers or Seloc.