over heating

[Chris T]

My Atomic 4 running at 1200rpm heats up to 190deprees at 35lbs oil pressure.
When I increase the rpms to to 1800 the temp go to 200-210.
Speed increases as well to 5kts. We have good water flow. I thinking that
a bollard test at the dock might help by adjusting the distributor. Any ideas?

Thanks Chris

FWC engine

[rigspelt]

Good water flow measured where?

[hanleyclifford]

Is this an early or late type engine?

[Concord]

Too much bypass

If you have good flow and still too hot you are probably bypassing too much water around the block. I would start by pulling off the Thermostat Cap if you have a newer style engine and check the condition. So far every cap I have pulled off had the internal boss rusted away. If you have a double acting thermostat the cap will not close off the bypass and you will continue to bypass.

You are probably due for a flush also.

Good luck.

[Chris T]

Is this an early or late type engine?

Late Atomic 4

[Chris T]

If you have good flow and still too hot you are probably bypassing too much water around the block. I would start by pulling off the Thermostat Cap if you have a newer style engine and check the condition. So far every cap I have pulled off had the internal boss rusted away. If you have a double acting thermostat the cap will not close off the bypass and you will continue to bypass.

You are probably due for a flush also.

Good luck.

Good Idea I'll examine the cap..

[Chris T]

Good water flow measured where?

Out the back of the transom.

[rigspelt]

Saltwater or antifreeze-cooled?
Water pump impeller intact?