1966 318 impeller?

New on here and have 1966 correct craft barracuda 318 haven’t had very long always wanted one and finally got it. Runs awesome bit ever since I had it the guy had a receipt for getting tune up and impeller but if I sit running at idle it runs up 180 looks like maybe clinging then but I go down the lake it drops down to 130 even 120 but go back to idle it slowly rises up again. Never had a boat like this but I love it I was guessing impeller since temp goes down while running down the lake. Any ideas or experience with this would greatly be appreciated.

Seems like 180 at idle would mean lack of flow. Definitely check clamps and make sure no way to suck air, also belt tension to make sure it's not slipping.

Did you run it at all on the trailer, feeding water to the raw water pump? Would be interested to see if you still hit the 180, if water is flowing out both pipes.

I appreciate the reply to my post and the hoses actually do look old and feel kinda old too so may just replace the hoses and check the thermostat and pretty sure this may work because it doesn’t try to run up and overheat all the time I really appreciate it a lot and thanks

Please tell me about the Sherwood Impellers. Mine is also a 1966 Chrysler 318 Poly A engine.

I am gathering parts for a refresh during the winter, and the impeller is unknown age so will be replaced.

Thanks,

Jack

A number of years ago at the river run one of our members decided to change his impeller before going out for the day. He had gotten a deal on aftermarket impellers from work. He pretty much spent the whole afternoon troubleshooting cooling problems until someone else gave him an oem impeller. Immediately his problems went away.

Part number 9959K was what I found also, but it is a 12 vane impeller & the engine manual calls the impeller 6 vane (on electronic page 17).

What can you experienced folks tell me about this? Is the 12 vane a modern replacement or should I keep looking for a 6 blade?

Thanks,
Jack