Need Xpert Help With 150 Merc OB

" Have been plagued with overh

" Have been plagued with overheat problems for the past 2 years with a Merc. 150 Saltwater OB (2000). Have replaced temp. sensor, t'stats and had pump checked at dealer (says ok). I have removed both t'stats and run water thru the flush connection. Water pours from both openings. Started engine with ears on lower unit and ran for less than a minuite and water only comes from left (facing from ground at rear) t'stat opening. Water comes just to the bottom of right side t'stat opening but does not run out. Sensor is not shorted or grounded, so wiring is not the problem. Still goes off at plane speed "sometimes". Have run engine for hours at 3200 rpm with no discoloration of head, fouling of plugs, etc. Have I checked the engine properly or am I missing something? Since the heads are offset (left lower than right), I assume this is why water favors the left side when running with t'stats out? I am by no means an xpert. Please help! "

"Fish,

Do you have a temp g

"Fish,

Do you have a temp gauge? What temp does it show when the alarm goes of?

It sounds like you have a leaky gasket at the water pump base. I always use a little gasket cement on these gaskets, even though the manufacturer does not call for it. Frequently the gasket between the impeller plate and the lower housing will fail. There is a thin strip that runs through the middle of this gasket, and it must seal for the pump to work properly.

That is my guess, but there could be other problems with the pump that would cause overheating also. I don't think it can be seriously overheating or you would have destroyed the engine by now.

If the dealer did not remove the lower unit and inspect the pump, I would advise you to do this. I have seen water pumps on brand new engines that did not work properly many times.

"

Tony; Have ordered gauge to m

Tony; Have ordered gauge to match temp. gauge sensor that is on engine since it doesn't read water temp. but rather head temp. Said about 3/4 weeks from local dealer. Laser gauge has been used and temp. at alarm sensor is about 165 degrees with t'stats in and at 1700 rpm with ears installed. Water temp. at taletell is 150 degrees.