Mr. Cool HX not so cool.

[Skipper]

I installed new Mr. Cool hx in October of 2021. Universal M18.

In 92 engine hours, the tubes are already constricted with calcification, and the engine temp is trending up. Also the exterior case has bubbled some.
See pics. The one showing the calcified tubes is via mirror, so it might look optically confusing.
Zinc is kept fresh.

I have also included pics of the original 1984 Sen-Dure HX (gold color). The tubes were clear when I removed it for replacement. Even after 1,487 original hours.
I replaced it for several reasons. It was a 4 hour job. And cost $300

So how does the Sen-Dure last 37 years and 1,487 engine hours, and the MrCool lasts 3 years and 92 engine hours?

This is the cupro nickel seawater version.

Emailed Mr. Cool days ago. No response.

Any ideas? Are the tubes smaller?

 

[dmax]

Is your engine running at a higher temperature with the new HX? Above 160 degrees salt will precipitate out of the water so it is recommended that you use a 160 degree thermostat for ocean use.

 

[kloudie1]

Heatex fouling is a very complex phenom. Usually, it is related to the surface (where it fouls) temperature being too hot for the solution iinside.. Some things might be a thermostat that is failing, something restricting sea water flow (Impeller, kink in hoses, partially plugged sea water strainer, partially plugged thru-hull, partially plugged sea cock..) If the tubes are better heat conductors, the surface temp may be slightly higher than on the old ones (long shot). I'd be looking at the sea water flow, and making sure that is as high a flow rate as possible.. Good luck.

 

[Skipper]

Is your engine running at a higher temperature with the new HX? Above 160 degrees salt will precipitate out of the water so it is recommended that you use a 160 degree thermostat for ocean use.

No, was normal. 165 thermostat as always. Recently trending up slightly due to developing constriction, hence the HX inspection.

 

[Skipper]

Heatex fouling is a very complex phenom. Usually, it is related to the surface (where it fouls) temperature being too hot for the solution iinside.. Some things might be a thermostat that is failing, something restricting sea water flow (Impeller, kink in hoses, partially plugged sea water strainer, partially plugged thru-hull, partially plugged sea cock..) If the tubes are better heat conductors, the surface temp may be slightly higher than on the old ones (long shot). I'd be looking at the sea water flow, and making sure that is as high a flow rate as possible.. Good luck.

Thank you. The flow out the back of the boat seemed normal / same as previous. Until recently when I really scrutinized it due to temperature trending up during long motoring back from wind-ceased sail.
Although visual might be an inaccurate gauge. Will check the entire flow route.

 

[jssailem]

You might test the water temperature at the exhaust. If it is hot, not just warm, then it signifies an issue that you should seek the cause. I would use a digital thermometer rather than just sticking my hand in the stream. I once used my wrist to check the temp of my baby daughter's "warm milk" . It burned the crap out of my skin. Left a mark. My wife, sitting at the kitchen table, just laughed.