Telltale signs of overheating

[Manny]

Other than a temp gauge, what are signs of a diesel engine overheating? Thursday, since the winds were light, I ran my Renault diesel for the first time since spring (I use my outboard as my primary). After a few minutes the temp gauge was showing 235 degrees which is too high, previously I never saw it go past 180. I'm thinking the gauge or sensor may be faulty due to the fact that the engine ran just fine, pumped plenty of water, didn't smoke, didn't leave soot all over the transom (which it likes to do), and pushed the boat just fine. The engine compartment seemed a little warmer than normal but it was a hot day. Oil level checked out okay. I intend to get a handheld Pyrometer to test next time out. Should I have noticed any difference in the way the engine ran?

Manny

 

[CalebD]

Sound.

Keep an ear out for the general sound of the inboard engine. If it changes at all that is worth noticing.
Smell too.
Feel: vibrations that are different than 'normal'.
See: smoke from engine is 'normal'.
Touch: is it hotter than it usually is.
Luck: hope for the best.
Do not touch your tongue to it to taste it as it may be hot.

 

[sailaway78]

Engine temp

Your engine will run fine at 235. It is hotter than it should be, but at 235 I don't think you would get excessive smoke or any indication of being too hot. Don't assume that the temp. guage is faulty, and find out for sure what is going on. 235 will probably not be harmful to the engine, but it is getting close to a harmful temp. If it's fresh water cooled, thats probably at or close to the temp when you begin loosing coolant, then it will definately overheat. The infared temp guage is probably a good idea. Then you will know for sure.

 

[John]

Infrared thermometer

Sometime ago I had a problem that I reported here about engine overheating. Somebody suggested I get an infrared thermometer. Cabella's sells one for about $30 and it worked fine. I think it's worth the purchase.

 

[porsche]

loss in power

when an engine starts to over heat it will first lose power. The rpms will drop off and it will make more noise than usual. DON'T let it get to that point get an inferred temp gun and if it is hot as you say find and fix. You did say that it was pumping water fine are you sure??? double check this. Alan

 

[Manny]

No power loss

Thanks for all the responses - I didn't have much time to investigate/troubleshoot the other day. Hopefully this coming weekend I can tinker. It's really strange, I swear the engine was actually running better than ever while the gauge was reading that high, that's why I think it may be the gauge is off. It sounded the same, seemed more responsive, and I got over 5 knots at wot (which is the best I had with that diesel). The exhaust odor wasn't anywhere near as noticeable as before, and I didn't get any soot at all. Any time prior if I ran the engine hard I would get a little "smile" on the transom. As far as vibration, the one lunger shakes like crazy so I didn't notice any difference. Water was definitely pumping, it always surprises me how much water shoots out of the exhaust considering the size of the water hoses. It is raw water cooled (forgive me if that is the wrong term - it just pulls water from the seacock straight through - no heat exchanger). I checked the main hose from the seacock to make sure it wasn't collapsing while running at 2/3 throttle.
Other than the intake sucking in some of the weedy stuff growing in the marina through the strainer, I can't see what would have caused the engine to overheat, nothing has changed.

Manny