I had apparently sucked some kinda crap floating near the ramp once in the stbd side, looked like something that was lining the underside of the dock and was just lurking......waiting to make it's way in and ruin my chance to take my cousin for a ride on the boat. Since then I start, get oil pressure and then I keep at 1200-1500 as you say above. I usually double check water is flowing through exhaust and usually don't move from the dock until the water temp gauges move. Then it's normal idle out until about 150ish temp and away we go. I have had 0 issues since adopting this method. There is opinion that it may have to do with the way the 496 cooling system lets water out after running as in to flush out salt for those in salt water, I dunno if that is it, but like most I have a routine I keep every time I go out.

Good luck, I was glad ours was a free fix. Is that even possible??

mercruiser last year had a 2 year run on these impellers being out of spec from manufacturing. The problem was fixed mid year last year. They caused priming issues and water volume issues along with over heats or any one of these issues. Also any worn / scared areas in the impeller housing can cause cavitation in which form air bubbles in the water flow in return can raise temps. We use the Hardin pump as well rather than the Gen VII OEM pump.


We also use a temp gun all over the engine, t stat housing, water circ hose and manifolds & risers to see what running temps are compared to T-stat and temp gauge on the dash, plus compare that with temp on the scan and or smartcraft gauge. Good luck

BUP, I just want to make sure that this is it, then its getting new pumps, the other side looks brand new. I have used worse in my 292 but the smallblocks sat way lower and did not have to pull as far. Did not have water pressure gauges or manifold temp sensors on the 6.2s so who knows it may have been doing it just idleing away from the ramp on my other boat. Just never knew.