This is on a built Gellner Engineering 514rated hp 454 built block. WOT runs at 170 temp I have been told from dean this is hot for the boat but was told from someone else its pefrect. Can anyone advise?

If you dont have a t-stat that is way high. If you do have a t-stat and its a 140 degree, that is high. If you have a 160 t-stat that ok. If Dean told you thats high for that motor, then its to high for that motor.

Just my .02.

John S.

What's the oil temp?

I am no expert but I totlally agree with above.

Make sure its not the sender. Is it a new one? The last 2 senders I bought were both off.

I think its rated at 140degree. My oil temp running on a stock mercruiser 454 oil cooler is normally 240. Actually the oil cooler is another questions. Dean also suggested changing the oil cooler. I do not run the boat for more then a few mins if I got WOT. But I will curise at or around 4500rpms but the temp builds quick. I had another guy explain that the oil cooler is stock on many other mercruiser motor and is fine.

Formula 31 is correct in regards to the sender.
Also, make sure your sender is matched to the gauge. It is an engineered system and both the gauge and sender must come from the same manufacturer. Do not mix and match.

Check the engine at the thermostat housing with an infra-red heat gun. Most boats I survey are running 18-22 degress cooler than the gauge reads. Electric gauges are notoriously inaccurate and should be used as an indicator only. I still think 240 is too hot for oil temp.

Back in the water and I have seen that the temp is 160 but as I run the boat, temp will increase to nearly 170ish!!

mine does the same thing brand new sea water pump, themostat, and engine circ water pump runs about 160-165 as i open it up 170-180 gets to 180 and drops right back down new auto-meter marine gauge and sender (electric) and a new 454 built to 420 specs.