1991 Honda 40hp Operating Temperature

[samo_ott]

I just put a temp gauge on my 1991 40hp by attaching the sensor to the top head bolt closest to the thermostat. My question is what should the operating temp actually be? It's showing me around 190F which I think is high. I previously had an old Evinrude 40hp 2stroke and attached the same gauge and sensor the same way and it barely maxed out at 140F. Is 190F high? I just changed my impeller and it did not change the temp at all. Do 4 strokes run that much hotter? Doesn't make sense to me. Thanks for any comments? Steve.

 

[Sea Rider]

Is that OB used in fresh or salt water, has low or high used hours ? Can't compare 2 different brand, different strokes OB's between them. Is OB having an overheat ?

Happy Boating

 

[ahicks]

I've never measured the water temp on one of these. Never had the need I suppose. I trust the fact that if it's peeing normally, there's no issue as long as there are no alarms sounding.

190 does seem high though. Water that warm is going to hurt if you get any on you.

The aux temp senders I've seen are not mounted to head bolts either. One I remember seeing recently replaced one of the lift ring bolts, also near the t-stat housing. This leading me to wonder what kind of reading you would get from a few different locations? No clue what you are working with, but if that's not too much trouble, that might be worth a try.

 

[Sea Rider]

Temp sensors are usually instaled on cylinder head to read current working temp and temp fluctuations as well, if sender is installed on bolts will simply read not a true operating temp.

Happy Boating