Are you in fresh or salt? I am in salt and I'm in the process of replacing the manifolds that were put on in 2004 (boat was used each season except 2006 when the deck was being replaced that summer). So these have just 6 seasons on them. My manifolds were getting hotter than normal and the engine was running close to 180*, it used to run cooler, closer to 160, and I also saw some steam off the exhaust which I never saw before. The impeller, circulating pump and the thermostat are all new. I pulled the manifolds tonight and found one passage totally clogged on one, the rest necked down from what new one looks like. The other manifold did not have a totally clogged passage but all the passages were significantly necked down with corrosion. So if you are in salt with raw water cooled manifolds then I'd say yes it's time to take a look at least. The odd thing was that the hotter manifold was the one with all the passages still open, the one with one passage totally clogged was the cooler one. But both were still too hot to keep your hand on after running on plane...
_________________ 88 Four Winns 200 Horizon 4.3 OMC Cobra-4bbl 2002 Walker Bay 10/2012 Suzuki 2.5 2008 Walker Bay 8
1998 Jeep Grand Cherokee 4.0/Selectrac 2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II
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