Temp gauge bad or sensor?

[hilljroberts]

Took the boat (2004 22v) out for the first time this season. Over 15 minutes of driving I watched the temp sensor start at 120 and go all the way up to 250. My engine didn’t seem hot and was running like a top. With the battery disconnected, the temp gauge doesn’t go under 120 I feel like the gauge is out of alignment.

Should I start by replacing the sensor? I’ve heard of people sending gauges in to be rebuilt, is that an option?




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[chpthril]

Key on and sender wire disconnected, gauge should read lowest temp. Ground sender wire and gauge should peg full hot. This will test the gauge and circuit.

If the temp gradually climbed to 250, id be inclined to believe the gauge. So testing is in order.

[hilljroberts]

Crud ok, for how long I ran it on the first trip out (an hour before this last time) I would have expected it to overheat then. Seemed to be running great. Was hoping it was bad data to the gauge.

I have the marine power 5.7, where the temp sender on the engine? The impeller is 10 months old, I don’t think that’s the issue. People have mentioned a screen in front of the transcooler, could that be clogged?

I might take IR thermometer and just keep an eye on it.


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[Jetdriver]

The trans cooler is on the starboard lower side of the engine roughly below the spark plugs. Follow the water hose from the drive to the cooler. Remove that side of the hose off the trans cooler, the screen is on that front side of the cooler. I check/clean mine once a year at winterization (while I’m draining water from the system) removing that front hose is the easiest way to drain the cooler IMO.
I would think your engine would automatically shutdown if it was actually getting that hot. When i had a cooling blockage 2 summers ago, my 07 MP engine shut down at 190 and the engine was obviously overheating.

[hilljroberts]

Temp gauge bad or sensor?

Yeah to be clear there is no performance reason why I think it’s overheating, just the gauge saying it’s so high.

Took the hose off the cooler tonight. There was definitely some junk in there but I don’t THINK enough to block it. Still leaning toward a false reading the gauge reads 120ish like what’s in the attached photo whether the battery and or ignition is on or off.


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[chpthril]

It does not sound it ran hot, but I would treat is such, until preven otherwise. Gradual temp increases are typically accurate. Sudden swings in temp, either up or down, usually point to an electrical issue.

[hilljroberts]

Temp gauge bad or sensor?

Ok thx chpthrl. As soon as I can find the sender I’ll start testing the gauge/sender. Shouldn’t the gauge be well below 100 on a cold engine if it was working though?


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[hilljroberts]

Ok so I found the sender. Interesting results....

So if disconnect the sender and turn on the ignition, the gauge goes down below 100 and stays there once reattached, if I ground it jumps above 250, as soon i disconnect from ground it goes back to that 125 range.

So.... I feel like that tells me the gauge is sticking/reading bad, the sender isn’t working, or my engine is overheating lol.... help?


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[hilljroberts]

So took it out tonight, ran it around 60-90 minutes. Gauge slowly climbed to about 250 which is as high as it goes. Boat performed fine, no issues. Impeller is only a year old replaced last spring, definitely pumps water when on a fake-a-lake.

I’m gonna try to replace the thermostat this weekend i guess, shrug. Next time i test I’ll bring a infrared thermometer and shoot it by the sender. The engine was still decently warm 90 minutes after coming to shore tonight, so I’m now at least nervous the temp gauge is right.


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[hilljroberts]

Thermostat starts moving at 160 fine. (Took it off and heated it in water).

I guess next step would be to run it on a hose and see if the block next to the sender with an ir thermometer is running about the same as the gauge is as implying. If it’s not I assume it’s guage or sender at that point, replace sender and then if not replace gauge.

Did Faria do the 2004 gauges? How would I tell? I believe someone mentioned they rebuild them?


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[hilljroberts]

Ok, with IR thermometer everything checks out safe, all parts of engine range from 160-180. I put a generic temp gauge from west marine on and went high as well. I'm going to lean toward the sender being the problem now and get a replacement for that. What a pain in the a$$....

[hilljroberts]

Temp gauge bad or sensor?

I replaced the sender, and the impeller just to rule everything out even though the impeller is just a year old (our season is only about 4 months). It’s still running hot according to the replacement temp gauge, ranges between 200-225.

Any suggestions as to what else I can do? In checking the engine with the ir gun, I’m practically certain it’s not actually running hot.


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[NHskier]

The trans cooler is on the starboard lower side of the engine roughly below the spark plugs. Follow the water hose from the drive to the cooler. Remove that side of the hose off the trans cooler, the screen is on that front side of the cooler. I check/clean mine once a year at winterization (while I’m draining water from the system) removing that front hose is the easiest way to drain the cooler IMO.

Jet - this post saved my Memorial Day weekend! I can’t thank you enough. I live in a shallow cove and a huge gust of wind pushed me into some muck. I shut the boat off immediately and walked the boat out of the muck but not before sucking up enough to clog the screen. I was able to clear it with the boat in the water and get it back running correctly pretty quickly. I will be checking this monthly from now on. So thank you, from my kids and wife [emoji3]


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[Jetdriver]

Awesome man! Glad you got it worked out!