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I noticed a slow leak from my coolant pump on my starboard engine. I probably loose a cup of coolant about every 15 hours of running. Can't tell if it is from the rear gasket or front bearing seal. Has anyone replaced one on the 100 Hp engine. If so was it difficult? I see there are a lot of companies selling aftermarket pumps. Does anyone have any experience with the aftermarket ones? Any help would be appreciated.

we replaced one years ago. we have 75s but i think they must be very similar. we used a genuine yanmar because we were in bahamas and didn't want to risk a problem. bottom line, it's pretty straight forward.

Thanks, it does looks to be one of the easiest items to replace on the engine.

I've got an intermittent coolant leak on the port engine (75 hp) and can't find it.

The coincident environmental factors are:

- the engine has been run to operating temperature
- there is a storm (low barometric pressure?)
- engine is shut down, and everything inspects ok
- it gets cold during the night
- the next morning, there is coolant on the diaper under and aft of the transmission (verified that it is not trans fluid.) ... it's usually the amount that is in the coolant reservoir. For example, if the reservoir is 3/4 full at night, it's at Low the next morning.

Does this sound like it could be the coolant pump seal or gasket?