I have a 502 efi, I've replaced the impeller , thermostat , and water circulating pump, and still nothing has changed. Engine gets up to about 170 but the risers get so hot and the water out exhaust is steaming, any ideas ? What the hell do I replace now? I have a boat load of girls that want to go out this weekend!!

check your oil cooler for debris from the old impeller. the best thing to do is is to pull it off the engine and take coat hanger or welding rod and probe all hole in the cooler.

I'll take care of the girls while you work on the boat, problem solved was the impeller intact when you pulled it out............. your water flow goes from the sea pump to the PS cooler on the bellhousing, then to the cool fuel cooler, lower-lower right side, then to the oil cooler that's mounted vertical on the front of the engine, then to the thermo housing, there has to be lockage in there some where

Impeller looked just fine, I replaced it at the beginning of year also, and I'm still getting a good flow of water out the exhaust that's why I'm confused, thanks guy!! 33 outlaw, plenty in ct to go around lol

is just the one engine ?

Thermostat oriented correctly?

Twin but only 1 motor is having the issue

How's water pressure? If that's good and a riser is hot I think you've located the issue.

Both risers are only 2 years old, and wouldn't think both would go at the same exact time.

External water hose in the transom assembly dry rotted - cracked letting air in with the water

Exhaust manifold and riser water jackets rusted up / scaled up / and or very restricted how ever

the inlet adaptor inner transom assembly collapsed or restricted