Engine running too cool?

superbenk

Commander
Joined
Oct 27, 2008
Messages
2,033
Had the boat in the driveway on muffs idling & the temp went up to about 150? where it stayed. Then took it to the river & ran it. Idling at the dock waiting for the family & 5-ish miles down the river it stayed at 150?, but when we slowed to a no-wake speed entering a creek the temp eventually dropped to around 120?. Then the boat started sputtering & hesitating sometimes. Running back up the river on the way back to the truck awhile later it was sitting at around 120? even at 4k rpm. Then it backfired once and had some hesitation here and there.

Why is my engine running so cool? Shouldn't run at 150-160? typically one warm? The t-stat is brand new this spring and this was the first run on it this year. Wondering if this is the cause of these hesitations and misses I've struggled with for years? Is the choke closing causing it to run rich because the t-stat isn't closing? Thoughts?
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Engine running too cool?

Sounds like a defective thermostat to me. New ones fail, or it could have something in it.
 

Reinell-BRXL-191

Petty Officer 1st Class
Joined
Apr 18, 2012
Messages
295
Re: Engine running too cool?

I would for sure take the housing off and take a look, it is possible the o-ring failed or came off, and the t-stat is not sitting in the housing properly... or one of the spring clamps came loose and the t-stat is in pieces - The engine should get up to temp and stay that way within 5 minutes
 
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