operating temp question

Our boat runs 160 degrees all day long (351W carbed, with Protec). She occasionally creeps to 170, but for very short periods of time. We mostly run slower speeds around 18-20 when wakeboarding and maybe hit 35 when crossing the lake. very little time spent at WOT.

I called Nautiques of Orlando today to ask a question about oil and when I told them what temp our boat runs at, they said I should be running 140, not 160 and to swap my thermostat.

Manual states 140-170 is normal. Am I OK with running 160?

I have no idea what stat is in there. I will check it this weekend when I change the oil and oil pressure switch.

With a 140 thermostat in a PCM Ford, normal running temperatures will be much closer to 160 than 140. Running in the 160-170 range is pretty normal- I wouldnt touch it.

What is the temperature gauge say directly in the center of it? 160? That's what my 89 says. I was always told you read gauges at normal readings in the center. So you make a glance and know its fine. SkiDim says a little higher temp makes fuel atomize better and a 170 temp is not all that high. I like the boat temping at 160 personally.

Don't trust the gauge. Due to voltage voltage drop the readings are higher one the gauges. This is due to poor grounding. I run a 143* in the CC it runs normally 150~160. Supra runs a 160* and it runs 170~180.

89Martinique wrote: Don't trust the gauge. Due to voltage voltage drop the readings are higher one the gauges. This is due to poor grounding. I run a 143* in the CC it runs normally 150~160. Supra runs a 160* and it runs 170~180.

Good to know. I have access to an infrared thermometer and I can double check the temps where the sensor is located just to be sure.

I also ran a fresh ground and a negative bus bar to the underside of my dash with all new grounds going to every gauge on my dash. I'm pretty sure I've got the poor grounding issue resolved.

The gauge used to read fine, then peg out after a few minutes and stay that way all day. Since I added the bus bar, everything has been reading nice and steady.

SNobsessed wrote: Gauges are not grounded at the dash, so that has nothing to do with readings. Supply voltage drop can affect them though. I run 150-160 deg F. You are good as is, IMO.

So where are the gauges grounded? Now I'm curious.

Gauges ground through the sensor (on engine). Only the backlight is grounded at the dash, which has nothing to do with the accuracy.

Hollywood wrote: AKA... the sender wire IS the ground. JPASS, careful what "advice" you take

Good to know. Thanks. Just replaced the sensor last month. So I know it's good.

I hear ya about heeding advice. We've only had our SN since June, so we are still learning things. This site has been priceless for it's wealth of knowledge.

I'm pretty sure my running temps are OK based on everyone's replies and the owner's manual. When the boat is down, I'll have a look at the stat just to be sure everything is OK.

OK, news to me about the 2nd coil, I stand corrected.

Before I replaced all the wiring from the dash to the motor on my 1984, my temp reading would jump every time I switched on the rear bilge blower. Now it doesn't budge. I had lots of voltage drop at the 8 pin connector, and some corrosion under the wire terminal crimps.