Separated the exhaust elbow from the stock exhaust manifolds. There appears to be no signs of water...just looked like dark exhaust chambers. Is there anything I should look for or should I pull the entire exhaust manifold?

Turbulators looked ok.

Checked all the spark plugs, all of them looked great. The only issue was the four on the starboard side were not tight at all. The four on the port side were tight.

Are there any shops that will test and clean the manifolds?

You may also want to check the transom assembly. I saw a 496 ho similar situation with salt. It was 1/2 closed off due to corrosion where the engine pulled lake water through the transom assembly. Took a while to find and didn't fully overheat just running warmer than it should

x2

I'm getting some water in the bilge, would a bad actuator cause the engine to run hot? Since I have the elbows off I may go ahead and replace the circulating pump. I'm sure it's the original.

Yes, that could be a culprit too. When they go bad, they usually only leak over 3000 rpm.

I guess it's time to purchase a couple rebuild kits. The exhaust manifolds and elbows look good, I can't see any corrosion in the passages.

Looks like the starboard actuator connects to the water pump. Do you have to pull the seawater pump to rebuild the actuator?

Did someone say there are mercruiser rebuild kits for the air actuators? The local mercruiser dealer says they do not exist.

There used to be, but I haven't looked for such.

Member "BUP" would know for sure.