2005 4.3 running hot and loud

[Ds0610]

Hey guys, I've tried to search as much as I can but I have a 2005 4.3 that I replaced the impellar last year after that I had a leak in the water displacement valve and replaced it. Now my issue is that it is running hot (180-190) and seems louder than it did last year there is plenty of water coming out the exhaust when I run it on a hose any help would be greatly appreciated!

 

[Bt Doctur]

if running hot you always start with the impeller first, drive should be a GEN II so worn/missing O rings in the connector guide tube.
Bad T-stat, clogged manifolds/elbows

 

[Ds0610]

My concern with trying the impellar is having to tear apart the lower unit and I'm not sure it addresses the louder running. Plus it was replaced less than 5 hours of run time ago

 

[GA_Boater]

No motor running on muffs is quiet.

 

[tpenfield]

A 454 running on the muffs is sweet music

I would check for blockages in the cooling system. Maybe the remains of a previous impeller are located somewhere inside the engine's cooling passages. Less water flow means louder engine.