Re: 260 Mercruiser not cool enough- why?
So then why do we find a good bit of salt water boats running without thermostats? Just curious.
Because they're idiots who don't know what they are doing!
Without a thermostat the engine can NEVER get warm enough, the oil doesn't reach optimum temperature and neither do the cylinder bores and pistons. This creates, among other things, much more wear in the engine. Contaminants in the oil don't boil off, and the oil becomes acidic. If the engine is EFI/MPI then the ECU continually runs the engine rich as it thinks it's still too cold... More fuel, more wear...
If the engine gets too warm with the thermostat in, then there is a problem to be fixed, not masked by removing the thermostat, or drilling holes in it!! :facepalm:
Let's look at what we have established is good and working properly...
Drive water pump and associated plumbing. Elbows are clear and free flowing, as are manifolds. Thermostat is new (and tested in a pan of boiling water and a thermometer I hope)... Check balls and springs in the t-stat housing are new/working properly... Here's an idea, put a section of clear hose over the balls and you should be able to see them working.... Another idea is to remove the hoses from the elbows (last place the water runs) and check you have the right volume coming out of the engine. We have established the volume going in is right, if there's not the same coming out then that would indicate a blockage somewhere. It would then be a matter of checking the flow at various points to narrow down where said blockage might be...
Another option is to rig up a pressure gauge in the water line from the drive and see what the pressure's doing when hooked to the engine... If it's too high, a blockage somewhere....
HTH,
Chris.........
