Raw water temperature or pressure?

[HeadedToTexas]

Rather than roll the dice that my 2007 Cummins QSB is compatible with Mercury's SmartCraft Connect, I have decided to replace the old DieselView unit with some gauges that simplify monitoring. The entire suite of variables will still be available through the SC1000 digital display including both raw water temperature and water pressure. It seems like water temperature is the more common of the two variables to monitor, but water pressure would lead temperature as an indicator of problems, true? Whether it's a clogging strainer, failing impeller, or burst coolant hose, pressure would fall before temperature would climb. So does that make water pressure a better indicator of impending problems?

Or it could be that pressure is a better indicator of critical failure, but temperature is a better indicator of problems that indicate a need for maintenance. I may be a data guy, but I'm not a diesel mechanic. What would you guys do if you could only have one of those two gauges?

 

[rslifkin]

On the raw water side I'd either want to measure pressure or exhaust elbow temperature. Those will be the 2 fastest indications of low or no water flow (pressure will also vary a good bit with RPM). Temperature elsewhere in the raw water circuit is likely not a very useful measure.

 

[Comodave]

We put Borel Manufacturing alarm system on several boats and they worked well and are simple to install. The exhaust water sensor is like a big tie wrap that goes on right behind the exhaust water injection l. It will sense lost water in a couple of seconds. You can also put a Water In Fuel sensor in the Racor. And a high water alarm. Much easier than messaging with all separate sensors.

 

[HeadedToTexas]

I like the Borel system and will likely have one someday. In this case, there are no new sensors as these are all variables the Cummins QSB is already measuring. I am just deciding which to have dedicated gauges to display. They look like analog gauges, but they display digital data from the SmartCraft network.

 

[Bmarler]

It would depend on where the sensors are located. If you measure temp just before the elbow it would be a good indicator of issues. Once you have a base line temperature you can monitor for change. I do this with my exhaust temperature and it lets me know if the strainer or impeller needs attention.
Measuring incoming raw water temp would not be as useful.
I also agree that pressure would be good to have. You might see slow changes over time as things wear or clog.
Differential pressure across the pump would be even better.