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View Full Version : LT1 Temp shot up at idle?


caliguyinTN
08-18-2006, 04:43 PM
Yesterday on the lake the engine temp was perfect all day. We decided towards the end of the day to go to the marina. We idled in through the no wake zone, got to the dock, shut off the engine and the marina was already closed. Got back in the boat and idled back out. But this time the temp gauge started to climb and it got about 3/4of the way and I put it in neutral to shut it off and right after that it started to go back down instantly. I shut it off anyways and then turned it back on and preceded to idle out and the temp was fine for the rest of the evening. Any ideas? The MC dealer said today it sounded like the thermostat, not the impeller. I bought both but have not changed them yet, its too d*mn hot out. Could it be the intake for the water may have been plugged? The lake is not mossy or full of weeds? If anyone has had this happen, I'd love to hear about it? Also I read somewhere on here about drililng a hole through the thermostat? The thermostat I bought says drilled on the package, so i'm assuming I'm fine.

LakePirate
08-18-2006, 05:04 PM
The thermostat is the fastest and easiest to replace. Wait, doesn't the LT1 have 2 thermostats?

bigmac
08-18-2006, 05:04 PM
Yesterday on the lake the engine temp was perfect all day. We decided towards the end of the day to go to the marina. We idled in through the no wake zone, got to the dock, shut off the engine and the marina was already closed. Got back in the boat and idled back out. But this time the temp gauge started to climb and it got about 3/4of the way and I put it in neutral to shut it off and right after that it started to go back down instantly. I shut it off anyways and then turned it back on and preceded to idle out and the temp was fine for the rest of the evening. Any ideas? The MC dealer said today it sounded like the thermostat, not the impeller. I bought both but have not changed them yet, its too d*mn hot out. Could it be the intake for the water may have been plugged? The lake is not mossy or full of weeds? If anyone has had this happen, I'd love to hear about it? Also I read somewhere on here about drililng a hole through the thermostat? The thermostat I bought says drilled on the package, so i'm assuming I'm fine.

What boat? What year? With a screwdriver, you could have answered the plugged intake question in the time it took you to type your post.

The drill is based on likelihood of reasons for the overheat and the simplicity of diagnosis. In this circumstance, most likely thing is a plugged intake so a) pull the intake hose off the transmission cooler and look for a glob of weeds. Next most likely is failed or failing impeller, so b) pull the cover and look at it, replace if necessary (Both of these things can be done on the water in a matter of a couple of minutes.

Last, IMHO, would be thermostat. Buy a marine 143 degree thermostat(s) and replace if the other two step yield no joy.

caliguyinTN
08-18-2006, 05:06 PM
96 Prostar 190 LT1 213 hours on it.

kpickett
08-18-2006, 10:27 PM
I've got a 94 with the LT-1. Every now and then something will get sucked onto the water intake grate (plastic bag, weeds, etc.). The temp guage will suddenly shoot up. When you shut off the engine, it backflows out of the intake and blows out whatever is there. My dealer told me that you can sometimes get an air bubble in there, too, and if you rev it a couple of times, that will sometimes take care of it.

Of course, the other suggestions are good, too, but if it clears right up after you restart, it was probably just a blocked intake grate.