mercruiser cooling water question

[Tex60]

I've got a boat that I'm restoring to operational status never had a I/O before. So on an outboard you have the pee hole how do you know if you have water circulating properly on this little 2.5L? As I understand it I have a impeller in the drive unit that pumps the water up to the top and then there is a belt driven water pump that circulates the water in the engine. I know from cars that if you don't have any water in the block that the water temp sending unit can give you an artificially low water temp. I just want to make sure I've got adequate water flow.

 

[haulnazz15]

Re: mercruiser cooling water question

If the boat is on a trailer hooked up to the muffs, water will come out of the relief ports near the transom and throught the prop. You find out that your outdrive impeller is shot when you engine temp starts to rise. You could always pull off the hose going to the thermostat from the outdrive while the engine is running. The hose should have a steady flow of water coming out; I would advise doing this with the engine cold to avoid burned hands.

 

[Tex60]

Re: mercruiser cooling water question

Thanks for the info, I thought about seing if there was a clear hose at Home Depot that I could temporarily swap out one of the larger hoses just to see if the water was circulating with out having it pump out in the boat. Then put the standard hose back in.

 

[fibersport]

Re: mercruiser cooling water question

How about feeling the riser on the exhaust manifold. I just installed a Mercuiser cooling system on my Chris craft engine and found that the top of the risers run cold in the driveway with the garden hose. As you put your hand further down them, they warm up. The manifolds themselves will also run warm, but the cold risers will verify your impeller. I would change the impeller anyway just to be sure, they may look good but after years of running they will get soft and loose their ability to pull in the water.

 

[Tex60]

Re: mercruiser cooling water question

I had planned to change the impeller out, I'm concerned with the circulation pump on the front of the engine. I also plan to do a swap out the thermostat just because this thing has been sitting for so long.

 

[fibersport]

Re: mercruiser cooling water question

An impeller and thermostat change are a good idea, I wouldn't worry too much about the circulation pump as long as it's a marine one. That impeller should be brass and should last forever, but bearings do go out so listen for squeeks and watch for water leaking out. Sent you a PM by the way, keep at it!
Greg