Hello all - first time poster.
I have a 1976 SeaRay 180 i/0 with a Mercruiser 165 L6 250ci engine. I bought the boat two years ago as a project and it has been a big one. After a lot more dollars and work than planned I have pretty well restored it and it is on the water.
The boat runs smooth and will cruise the harbor all day long sitting at around 25% mark on the temperature gauge. However as I open the throttle over 1500 revs the temperature gauge starts to creep up. It will stabilize around the 75% mark cruising at 3000ish rpm (25-30 mph) . However, if I push harder, or go to WOT it quickly climbs into the red. I have replaced almost the entire cooling system and am baffled.
The boat is raw water cooled and lives in the pacific, so raw water is coming in around 55-60 degrees.
In chronological order:
2010 1) Replaced the lower unit raw water pump and housing before I ever started the boat (sierra kit, ******** item 31862)
2010 2) The manifold was cracked and letting water into the #1 and 2 cylinders so it was replaced before ever starting the boat out. (Barr Marine - new part)
2010 3) Cleaned out rust deposits in the thermostat housing and replaced the thermostat (spring down right? - Sierra Thermostat kit 18-3650)
2011 4) Had the head rebuilt and installed a new marine head gasket (head done by west coast engine, gasket Fel-Pro Marine 17019)
2011 5) Replaced the engine circulating pump (brown box - new marine part)
2011 6) New lifters and push rods (sealed power)
2012 7) Replaced the exhaust elbow and upper bellows (sierra elbow, bellows and gaskets. The shutter was gone and not replaced)
In other things- compression is good and even 142-155 on all cylinders, the boat has a prestolite distributor, new coil, new oem plugs, and hot spark electronic ignition conversion. The engine is timed at 6 btdc. The engine oil pressure is 20-30 lbs from idle to WOT - I am running 15w40 conventional universal motor oil from walmart and a plain fram filter. The outdrive is propped with a new 19 pitch Aluminium Solas prop and WOT appears to be around 3800 RPM.
The hoses all seem ok. I am at a loss for ideas on what else could be going on here - any wisdom would be appreciated!
I have a 1976 SeaRay 180 i/0 with a Mercruiser 165 L6 250ci engine. I bought the boat two years ago as a project and it has been a big one. After a lot more dollars and work than planned I have pretty well restored it and it is on the water.
The boat runs smooth and will cruise the harbor all day long sitting at around 25% mark on the temperature gauge. However as I open the throttle over 1500 revs the temperature gauge starts to creep up. It will stabilize around the 75% mark cruising at 3000ish rpm (25-30 mph) . However, if I push harder, or go to WOT it quickly climbs into the red. I have replaced almost the entire cooling system and am baffled.
The boat is raw water cooled and lives in the pacific, so raw water is coming in around 55-60 degrees.
In chronological order:
2010 1) Replaced the lower unit raw water pump and housing before I ever started the boat (sierra kit, ******** item 31862)
2010 2) The manifold was cracked and letting water into the #1 and 2 cylinders so it was replaced before ever starting the boat out. (Barr Marine - new part)
2010 3) Cleaned out rust deposits in the thermostat housing and replaced the thermostat (spring down right? - Sierra Thermostat kit 18-3650)
2011 4) Had the head rebuilt and installed a new marine head gasket (head done by west coast engine, gasket Fel-Pro Marine 17019)
2011 5) Replaced the engine circulating pump (brown box - new marine part)
2011 6) New lifters and push rods (sealed power)
2012 7) Replaced the exhaust elbow and upper bellows (sierra elbow, bellows and gaskets. The shutter was gone and not replaced)
In other things- compression is good and even 142-155 on all cylinders, the boat has a prestolite distributor, new coil, new oem plugs, and hot spark electronic ignition conversion. The engine is timed at 6 btdc. The engine oil pressure is 20-30 lbs from idle to WOT - I am running 15w40 conventional universal motor oil from walmart and a plain fram filter. The outdrive is propped with a new 19 pitch Aluminium Solas prop and WOT appears to be around 3800 RPM.
The hoses all seem ok. I am at a loss for ideas on what else could be going on here - any wisdom would be appreciated!
