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Heating issue

Waterjunky

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Hello all;
Still having a heating issue in my boat and considering a new sensor . It’s a 95 7.4 Volvo penta, so standard bbc. When I was digging around to pull it out and try to find a replacement I realized there appears to be two. What am I looking at here?
I am considering a sensor because it runs fine at idle or any rpm until randomly spikes in literally 4-5 seconds. Already changed the thermostat with the correct super cool one for that boat.
Thoughts?
 

Carlson-jet

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One looks like a thermocouple temperature sending unit ( 2 wires) and the other for over heating?
25 years is a good run for either.
Replace both.
 

boatdoc55

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It might be time for exhaust elbows at 25 years. If the hot water can't get out the cool water can't get in.
 

Waterjunky

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Sorry about the delay in responding.... crazy Sunday and work today.
That's my guess also is the single wire is the actual sensor. At least historically that was how most rolled, but in the computer world we live in I'm not sure.

Any other thoughts?

My problem with risers is that I can run hard for 20 minutes and am fine. Idle the same and fine. Then all of a sudden in just a few seconds jump 50 degrees and set off alarms.
kind of strange. I am hoping that I don't have a bad wire in the harness shorting out or a bad computer doing random things.
 
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