one engine still gets hot wheni pin the sticks. it will run at 4k rpm ok but it is always 20* hotter thean the other eng. when i go wfo the temp steadily climbs till i back of to 3000 or so then it comes back down. i have huge offshore water pic up all new hoses, put new w/pump impeller and hsg on last week. all my coolers are new ecept the p/s cooler which happens to be on the eng that gets hot bit i ran a piece of heavy wire thru every tube in it and there are no blockages. i was thinking perhaps i hav a restriction in my exhaust but water is flowing out both pipes. any suggestions on what i might try next. thx in advvance, ratman

How is your water pickup?

new and huge

Bravo drive? Check the hose from the drive outside the boat all the way in. Have seen them go bad inside and restrict flow just enough to cause overheat at wot. What a b*%#h to find!! --- Jer

Had same problem 2 seasons ago. I replaced sea pump impellar, checked all hoses, checked the inlet tube at the drive, replaced thermostat...everything.......
I finally removed the thermostat completely and that cured the problem.
I replaced thermostat with a high-flow unit that I bought from Summit Racing. Been working great ever since.

I had same problem....replaced everything, still had overheating problem. Ended up blowing up engine before finding the problem. Problem was the hose that was in the bravo unit. It a small hose that connect thru the Gimbal unit then connects to the hose that connects to the sea water pump. It was almost complelty cluged with corrision. Who would ever think a rubber hose would have corrsion. If you check everything, I bet you thats your problem. Especially when it only happen a WOT.

I would pull the thermostat too, they are mostly junk, ive seen new ones no open, stick open, not open all the way. Easy check anyway.

Then get a piece of clear hose to use on one of the manifold hoses. Look for air bubbles especially at the high rpms.

Check your manifolds and tailpipes for restriction. Do you have a water pressure guage? If so, what does it read at WOT?

Removing The Tstat Isnt A Real Good Idea,W,ith It Out The Water Will Move To Quickley Threw The Block And Not Absorb Any Of The Heat,The Temp Guage Will Show Cooler Because The Water Is Always Going To Be Cold As It Now Moves Very Fast,The Tstat Is Designed To Slow The Water Inorder For The Water To Remove The Heat!Same Deal In Your Car,Hre It All The Time!You Really Need To Find The Problem And Fix It!Merc Or Who Ever Does Not Install Parts That You Dont Really Need!! Good Luck!