Startup Engine Heat (343) ?

[vision]

Assuming the new T-stat is good (should be safe assumption) you have a water flow issue. Either air leaking into the system as mentioned, or obstruction in the system. Not easy to find either when they are not in an obvious place. Finding a partial obstruction within the water jacket of the engine can be tough and sometimes you have to back flush the system (I assume the 343 is not partial closed cooling). I believe you already checked this but make sure the water strainer is not cracked or loose as well.

[laurie8888]

Just my 2 cents.... The engine also has a recirculating water pump adjacent to the Rwp. Nautique did a recall on some engines due to faulty pump, mine included. I am about to get it replaced. My engine also heats up at idle so let's see if it solves my problem. Also I have a squeak close to fan belt and recirculating pump, maybe the pump? My boat is 2012 200



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[ZachD]

So I finally got this resolved... All in all, the help on here was spot on (bad impeller and air leak somewhere). I was pressed for time with an upcoming Lake Norris trip and (with my lack of knowledge and calendar pressing) I elected to take it to the dealer. They were able to fix the issue with a new impeller (as me not seating the casing the first time correctly resulted in me frying the second one too). They also found some hose clamps that were not as tight as they should be and tightened those down. Big props to the guys at No Wake Marine in Cincinnati as they were reasonably priced for the service I asked them to perform and, probably more importantly, met my deadline that was specified when I dropped it off. It's worth noting that this was compressed compared to the normal lead time in the service department. The boat ran great down at Norris from the first startup. I'll continue to utilize this site and the expertise here as the dealership is a couple hours away from where I live, but if you're in need of professional help, I definitely had a good experience working with Adam Clark at No Wake.

[bandit628]

What is the part number for the thermostat?

[distinguishedmotorsports]

https://www.nautiqueparts.com/produc...-gasket-gm-tg/

if you have 04 and up 343ci V8, 02 and 03 use a different one. highly recommend nautique parts, they have a discount for forums members.

[scottb7]

The thermostat is not special. I had to replace mine a while back. I replaced with this one and fit and worked fine. You can pay $30 or $40 or pay $7 bucks up to you!!