Well. took the pump apart, looked perfect, installed the rebuild kit, NO JOY! Impeller was perfect, no debis in the pump. Any ideas?

are you starting to run lean on that motor. fuel issues.
circulating pump starting to fail or the belt loose or slipping that drives the pump
thermostat sticking partial or any blockage

just shooting in the dark.

Fueling spot on, this problem is just with one motor, it could be the circulating pump, as the temp has been creeping up. But thre is no leaking on the circulating pump, and everyone has told me they rarely fail. I'll check it anyway.
Happy Easter to all! Safe boating!

Have you verified the temps with a heat gun? Sending unit could be giving you a false reading.

I was running no thermostat for a year, just rebuilt the motor and the old man put one in, trying to make me nervous. I figured good 10 min warm up and then let the water flow. What are normal v8 operating temps i know my can runs around 220 when i open her up for a while

should be a 142* stat .....should run 140-155* ..... thats ideal ....if you have flow issues could be warmer ...m

could be a supply problem with the drive .....the TA can corrode and cause the hose to collapse restricting flow to the pump ......m

Well, I shot the manifolds and risers, and the port manifold is running 150-55, almost 40 degress hottter than the other side. Riser is fine, but I think I need to change the manifolds. Any observations?

I believe the recommended service life for cast iron manifolds in salt water is 5yrs max. You can service them a couple times by soaking in muratic acid and rodding them out. Yours are likely getting clogged up with rust scale and restricting flow of seawater.

I was thinking that, I'll remove it this weekend, and if it's really bad, I'll replace it. Thanks Thunder