Coolant Alarm

[Speedboat]

Coolant Alarm Sounding.

I've got a 2013 Mercury 175hp Pro XS Optimax Serial # 2B018990 model 175P73EY. Recently I was at the lake and had the alarm sound on my mercury. Switching the motor off I found I believed the cause to be the coolant system. I took the boat to the Mercury tech to have the motor diagnosed and fixed. I believe the cause for the alarm sounding is that the water pump and thermostat is due to be replaced. My question how involved is it to replace these two components? My mercury tech will be performing these task I was just interested so I would have an idea as to the cost of these repairs. All this said if the water pump and thermostat are the needed repairs.

[Speedboat]

Is it necessary to drain the lower unit oil/grease when servicing the water pump on this 2013 Mercury Pro XS identified in the preceding post?

[moetorola]

Is it necessary to drain the lower unit oil/grease when servicing the water pump on this 2013 Mercury Pro XS identified in the preceding post?

Not necessary per say, but a good idea to change.

All of the above is easy to do, by most anyone mechanically inclined.

I would also have them inspect and clean the strainer screen for the compressor. And regular maintenance like sparkplugs, fuel filter etc. etc.

[SilverFox579]

How did you determine alarm was coolant related? What are your water pressures at idle and WOT, also what is your idle coolant temperature?

A constant tone is a critical alarm and there are several things that can cause one.

No reason to drain lower unit lube to service water pump unless lower unit oil is due for service same time. Absolutely ensure strainer is checked & cleaned as necessary.

Recommended service intervals are in this FAQ topic at top of forum - Recommended Annual Maintenance or Winterization for Optimax Engines

[Speedboat]

I would like to thank everyone for responding to my inquiry. I deduced the alarm I heard was involving the coolant when checking my Merc Monitor at the Coolant indicator on the monitor screen to find the AL light blinking. when the motor was running there was the strong water stream from the pee hold of the motor, at idle the engine temp was at or just over 130* and I didn't notice the water pressure at idle. When at service technician I was told he couldn't determine the source of the alarm. I then checked my service records for this Mercury and saw it had been almost a year since having impeller and both thermostats replaced. This trip they were replaced. Now I hope when this weather passes I plan to go to local lake and make a run to see if all is right.

[lpugh]

In over forty years of bass fishing running Merc motors I have never had a mercury thermostat fail. I have had to remove them hundreds of times to clean the junk out of them holding them open. I am sure some do fail but my point is that it is actually quite rare

[Speedboat]

Thanks for the input.

[moetorola]

In over forty years of bass fishing running Merc motors I have never had a mercury thermostat fail. I have had to remove them hundreds of times to clean the junk out of them holding them open. I am sure some do fail but my point is that it is actually quite rare

And they are easy enough to check. A temp prob and some heated water on the stove suspended in the water by string. I test mine once a year as part of my maintence or sooner if an issue arises.
My T-stats are original to the engine, 2001.
Not saying an issue can not happen, but like you said rare. And the reason I check em.
Oh and do not modify the stats in a fishing motor.

[Riccochet]

I wouldn't say they never fail. Had one stuck open on my '14 150 ProXS. Coincidentally it failed when the gasket under the pump base plate also failed....what a nightmare that was tracking down what went wrong. I wound up replacing the entire cooling system.

[EuropeanAM]

I wouldn't say they never fail. Had one stuck open on my '14 150 ProXS. Coincidentally it failed when the gasket under the pump base plate also failed....what a nightmare that was tracking down what went wrong. I wound up replacing the entire cooling system.

That's why you'll see me send folks back 2 maybe 3 times to replace ALL THREE of the gaskets. The one below the plate (and the one below the base) both will drive you right to the brink of insanity if you don't steer yourself "back to the source".

[Riccochet]

That's why you'll see me send folks back 2 maybe 3 times to replace ALL THREE of the gaskets. The one below the plate (and the one below the base) both will drive you right to the brink of insanity if you don't steer yourself "back to the source".

The old motto stands. "We do it right because we do it twice"