Mercruiser

"its been sittin for 4 yrs , g

"its been sittin for 4 yrs , got it started , and on the water ,, only have reverse . wont got into forward .. and seems to overheat now alos."

"Replace the impeller and make

"Replace the impeller and make sure the water passages are clear of anything. Remove the shift cable from the mechanism on the motor and see if it will go into forward when you shift it manually. If it does, you'll need to adjust or replace the shift cable/mechanism. If it still won't go into forward, you have other issues that will require some disassembly of the gearcase. Since the impeller needs to go anyway, it's a good time to do this, too if you havea an Alpha drive. The Bravo and older big blocks have the raw water pump mounted on the motor but I would check out the whole raw water system, including the oil cooler if it has one."

"Tom: Jim N. is steering you

"Tom: Jim N. is steering you in the right direction to solve your problems. If it still overheats after you have done what he recommends, consider the following:

If your engine is raw water cooled (no heat exchanger), the thermostat can be rusted in a semi-open position from the rust and scale that developed while it was sitting those four years.

If it is fresh water cooled with a heat exchanger, the antifreeze is probably in need of changing and the cooling tubes inside the heat exchanger could be narrowed by electrolisis depositing calcium inside the tubes. It doesn't take long for clogging of the tubes when it sits for four years.

You can try to use an automotive heavy duty radiator cleaner chemical to clean it. But, it is only a matter of time before it clogs again or even worse, the tubes could perforate then you'll lose the antifreeze. I would have it cleaned/repaired professionally for insurance."

Also if possible and the boat

Also if possible and the boat is out of the water and the outdrive is off. Dorce water or air down the water intake hose to free up any crap (impellers or acorns) that may have gotton up inside there from beaching or storage.

My friend had acorns stuck up there along with rocks that caused over heating all season for him.

Those #%*&@? mice and

Those #%*&@? mice and chipmunks! They will store food and build nests anywhere! I went to service my 4WD trans. last spring and blamed the boys for using it offroad and hill hopping. Turned out to be a field rat built a huge nest on top of the transmission--I guess he liked the warm winter nights.