I have a mercruiser 260 s/n 5876132 gmc 350 fresh water cooling system.. i have been wrenching on it for a couple weeks trying to bring it back from the grave which is why i bought it. It was overheating so i flushed the system multiple times and it seemed to get better it was definatly dirty/rusty in the system. so everytime i flushed it i would follow up bye running it up for 10 or so min keeping a eye on the temp which eventually evened out at 160ish which seems to be the operating temp arrow is right in the middle of the temp gauge. anyways so after all that i ran it for 30 or so min and it stayed right there so i figured that was all it was and i would be fine so i took it to the lake.. once i got there it fired right up and seemed fine. then as i was leaving the dock i was throttling not even reaching 2000 rpm maybe 1500 basicly doing a wheely so i began to adjust the trim as i adjusted it down it would bog the eng which lead to the killing of that eng and when i tried to start it would just crack...so i brought the trim up and it fired right up but if i lowered it it killed it. and after that the eng started getting hot again so i am not sure if that problem is effecting the temp or if i still need to find that problem and also what is causing the trim down to bog the eng down in turn killing the eng
