Merc 4 stroke EFI 60 hp Cooling Question

[jmoser]

4-cylinder 4 stroke 60 hp EFI outboard; vertical block with #1 cyl at top, #4 cyl at bottom.

Does the water jacket design and cooling water flow pattern produce different temps from top to bottom cylinders?

May have to break out the infrared temp gun to solve my curiosity - especially at trolling speeds where low RPMs limit water flow rate.

 

[jeffersondodson561]

Re: Merc 4 stroke EFI 60 hp Cooling Question

At lower rpms the pressure in the block is limited to thermostats opening and the build up of pressure to pop off the Pressure Relief Valve, so it stays for a longer duration until one of the two open. At higher rpms a lot of pressure is put into the block from the sheer force of the water at the gearcase. So the PRV will be constantly open and the thermostats in theory should be working less. But the water comes up the gearcase, through the midsection, through the block and then the heads. Most of the water exits the propshaft.