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Someone dug this one up from a while ago..............

Another thing to look at is yout oil level...............if it's too high the crank hits it, and it gets hot & foams.

I had this happen to one engine...............level looked good on the trailer, but was a bit high in the water cause of how the boat sat.

Just a thought

Wette Vette,
The bypass/dumpvalve you use after your pump will help lower temps. More water is passing through the cooler without forcing its way through the block and exhaust. Is that reasonable?

BadDog,
That is a reasonable assumption, but I haven't tested it out to see if it actually makes a differance. I suppose the dump could also be installed before the cooler and less water will be flowing through the cooler. It is my opinion that there would be no difference in the actual oil temps.

I ask because I just installed a dump valve on the downstream side of my oil cooler and my oil temps are a few degrees cooler than before. The seawater pump has to be flowing more volume to feed the bypass and block. I will post when I have more results. Previous oil temps were 200 at cruise and 220 at WOT. Never varied in any water temps. Eddie Marine cooler. By the way, what size and how many holes do you run in your t-stat? I have three 5/32 holes and could not get the block temp up in 55 degree water. Using Stainless marine crossover. Oil was OK.

I run the 142 t-stat that came with the crossover. I didn't modify it and the water temps hold at around 150 once warmed up regardless of water temp or if I am idleing or running WOT.