Engine Temperature spike

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JoeGer
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Re: Engine Temperature spike

Postby JoeGer » Mon May 06, 2019 3:07 pm

Ok... I disassembled, cleaned and re-assembled the strainer gaskets. Made sure the small tapered o-ring gasket under the strained lid plate was seated and cleaned. Long-story short, both strainers were robustly “boiling” with intake water!! So, I can check that off the list. I will grab my cousin and we’ll have to do a full drive test to make sure the temp issue is resolved. As for start-up, the engine warmed up normally and both stayed nicely between 145-165. Fingers crossed this ends up being an easy fix. But not out of the woods yet. Thx, friends, until next time!
1984 28’ Sedan Fly-bridge
Twin 318
Lower Detroit River, USA

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JoeGer
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Re: Engine Temperature spike

Postby JoeGer » Tue May 14, 2019 9:53 pm

So, it was a nice night and was able to take a serious longer ride at various speeds. Regarding my temp issue on STB engine, I did realize some temp spikes, but much less frequent, and still all occurrences at lower speeds (1500rpm or less), and always immediately self-correcting. Furthermore, when it corrects, the temp drops below 160 to approx 140. The whole cycle takes about 15 seconds from the time the temp starts rising, to peak temp (220+) then back to 140. FYI, when cruising 15 knots at 2000rpm, there’s absolutely no issue - temp stuck at 155-165 consistently with no fluctuation. @FastJeff, I did not have the “help” on board to verify the sender unit with the IR gun.. perhaps next time.
1984 28’ Sedan Fly-bridge
Twin 318
Lower Detroit River, USA

Fastjeff
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Re: Engine Temperature spike

Postby Fastjeff » Wed May 15, 2019 6:51 am

Shame on you!

I suspect your t-stat is sticking and causing those weird temp spikes.

Jeff
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington

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JoeGer
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Re: Engine Temperature spike

Postby JoeGer » Wed May 15, 2019 7:31 am

Hmmm.. just replaced it.
1984 28’ Sedan Fly-bridge
Twin 318
Lower Detroit River, USA

jralbert
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Re: Engine Temperature spike

Postby jralbert » Wed May 15, 2019 12:14 pm

Another hmmm.... because past posts pasted on the forum said their replacement stat needed replacement, too. the BOOTB syndrome: Bad Out Of The Box. A cheap way to verify would be to swap the stat to the other side (if you don't mind the bit of extra labor).
-joel-
former owner 1988 '32 FB Sedan
Chesapeake Bay
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Re: Engine Temperature spike

Postby Fastjeff » Thu May 16, 2019 7:07 am

When you replaced it, was the t-stat housing semi-rusted? I had problems with mine (that caused by-pass leakage) and had to make a stainless 'gasket', with the stat riveted to it (and gaskets on both sides). That would not account for high temperature spikes, however. Hummm...

As Joel said, BOoftheB is a possibility.

Jeff
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington

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JoeGer
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Re: Engine Temperature spike

Postby JoeGer » Thu May 16, 2019 3:20 pm

Behavior seems indicative of a bum T-stat. And now I’m 2nd guessing whether I did or didn’t put the “new” one in or not. Anything is possible. Time to change it out again, dag-nabbit. Anything for my Big M! :lol:
1984 28’ Sedan Fly-bridge
Twin 318
Lower Detroit River, USA

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Re: Engine Temperature spike

Postby jralbert » Thu May 16, 2019 4:59 pm

Hold on...save yourself some trouble, maybe. Stick it in a pot of hot water and see what happens. Decide whether to replace based on whether it rises to the occasion
-joel-
former owner 1988 '32 FB Sedan
Chesapeake Bay
twin 318 / 240 hp
Potomac MD

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bcassedy
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Re: Engine Temperature spike

Postby bcassedy » Thu May 16, 2019 8:35 pm

If you want to ensure you know when you swapped out a t-stat, you could take a file (hardened steel) and scratch the date of change into the t-stat. It's brass (softer metal) and there are plenty of spots where the date could be etched and it won't affect t-stat's functionality.

Bill
Bill & Sharon Cassedy
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Re: Engine Temperature spike

Postby Fastjeff » Fri May 17, 2019 5:56 am

Joel is spot on again: test that sucker in a pot of boiling water. You can watch it open and close.

Jeff
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington