Engine temp low

[Skiphreak]

2003 Malibu RLXI - has operated at 160 degrees like clockwork since I purchased three years ago. Today, I could not get the engine temp past 140ish. Boat seemed to be operating normally otherwise.

 

Doubt this means anything but we are on vacation and the boat has been sitting in the water on a mooring since last week, whereas at home it gets pulled after each use.

 

Any ideas? Thanks

[addkerr]

Thermostat issue.

Either a bad thermostat, as I think they fail open. Or sometimes a bit of corrosion or sediment build up can get stuck in the stat and causes it to stay open slightly, leading to low temps. For the cost, I would just swap it out for a new one.

[Skiphreak]

@addkerr Thanks for the advice. Am I hurting anything by running it the next few days without swapping? I would rather wait til I get back home if I can.

[addkerr]

In my experience 140 is fine to run on. But if it's a bad thermostat it may get worse. If it's a small piece stuck then it may well clear itself. Try do some quick runs to get some pressure and temp up.

[UWSkier]

Don't recall what temp the engine switches from it's "warm up" fuel mapping to steady state but it might be above 140. The boat might run a little fat with that but shouldn't hurt anything.

[dvskier]

I’ve owned a 2004 SN since new. The same thing happened to me a couple of years ago, it was the thermostat. Easy fix, 330hp PCM Excalibur engine.

[chrislandy]

If you have an IR temp sensor, check the block temp.

 

Mine has read low before, turned out one of the terminals on the back of the gauge had corroded, thus increasing resistance and reading lower on the gauge.