rapidly fluctuating temp gauge - SBC
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rapidly fluctuating temp gauge - SBC
I'm hoping someone can point me in the right direction. Last Saturday had the boat out and everything was going great. While cruising home I looked down and the starboard motor was running VERY hot (220+) so I instantly shut it down. Luckily I had twins so getting back to the dock wasn't an issue. Occasionally I would start it up to try and circulate some freshwater through the engine but could never get the temp to drop.
The boat is new to me as of a month or so ago so I initially thought it was probably just the impeller in the drive (Alpha SS) so last night I replaced it. While tearing it down I found some fresh sea weed in the pickup ports which leads me to believe that was the initial culprit of the overheating. Went ahead and replaced the impeller anyways while I had it apart. Put everything back together fully expecting to have fixed the issue and I would be good to go. Started the boat up and now the temp gauge is fluctuating very rapidly. I took a video and posted it here to show what I am talking about. Sorry about the quality. It was getting dark and I only used my cell phone. when the gauge is straight up its roughly on the 200 mark.
https://www.youtube.com/watch?v=LuIuGCjzebI
I swapped temp sender with the port motor and got the same result. Also swapped gauges without a change as well. I then back flushed the oil cooler thinking it might be clogged restricting the water supply but everything was nice a clear.
Before this the motor was rock steady at 150 degrees. Has anyone had a similar issue? Any ideas before I just start throwing parts at this thing? I plan on doing a compression test later this afternoon after work and hoping for the best.
The boat is new to me as of a month or so ago so I initially thought it was probably just the impeller in the drive (Alpha SS) so last night I replaced it. While tearing it down I found some fresh sea weed in the pickup ports which leads me to believe that was the initial culprit of the overheating. Went ahead and replaced the impeller anyways while I had it apart. Put everything back together fully expecting to have fixed the issue and I would be good to go. Started the boat up and now the temp gauge is fluctuating very rapidly. I took a video and posted it here to show what I am talking about. Sorry about the quality. It was getting dark and I only used my cell phone. when the gauge is straight up its roughly on the 200 mark.
https://www.youtube.com/watch?v=LuIuGCjzebI
I swapped temp sender with the port motor and got the same result. Also swapped gauges without a change as well. I then back flushed the oil cooler thinking it might be clogged restricting the water supply but everything was nice a clear.
Before this the motor was rock steady at 150 degrees. Has anyone had a similar issue? Any ideas before I just start throwing parts at this thing? I plan on doing a compression test later this afternoon after work and hoping for the best.
Last edited by JimNut; 07-12-2016 at 11:34 AM.
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I've never seen a temp guage move faster than a tachometer. LOL.
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Location: Central IL / Green Bay, WI
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I have.
It was a puked head gasket on my 05 Duramax. Combustion gas in the coolant will make the needle whack. lol.
EDIT: It only did it at peak torque though....just enough cylinder pressure to push that much exhaust past the gaskets I guess.
It was a puked head gasket on my 05 Duramax. Combustion gas in the coolant will make the needle whack. lol.
EDIT: It only did it at peak torque though....just enough cylinder pressure to push that much exhaust past the gaskets I guess.
Last edited by Wasted Income; 07-12-2016 at 01:32 PM.
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Probably what it is with it seeing those temps.
I have seen many headgaskets push the temps up somewhat fast, just not that fast.
I have seen many headgaskets push the temps up somewhat fast, just not that fast.
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My EGTs were pretty high at the time...rolling into it pulling my boat with a tuner installed. lol. The first few times it happened, the needle moved so fast I thought for sure it was a wiring issue...."no way could the temp be raising that fast". Found out that wasn't exactly true. ha.
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This was the answer that I was hoping not to hear but kind of presumed it is the culprit. I will be running a compression check later this evening and will report back with what I find. Just hoping that I caught it in time and didn't crack a head...
#10
Debris can get hung up in the T stat and give pretty erratic readings too. Saw that with some broken impeller pieces years back.