This is perfectly normal behaviour. If the engine was pumping cold water through constantly the cylinder would never reach operating temperature and warm up. The thermostat in an outboard is slightly different from a cars enclosed system but works along similar lines to keep the engine at the correct operating temperature.Please help.
I have a Mariner 8hp 1998 saildrive, model 8MLSM.
Recently serviced with new impellor.
When running, the flow of water from the engine is intermittant. From full flow, the stream tails off to nothing, then after a few seconds comes back boiling hot and steaming, runs fine for a few seconds then tails off again. This is a constant thing, the cycle lasts about 15 seconds and happens the whole time the engine is running. Does this engine have a thermostat, and could it be this? Or is this perfectly normal. Any other suggestions greatfully received, otherwise back to the repair shop for another few weeks!!!