Re: Is my 4 cyl 50 hp Merc running too hot???

[billw]

I had one of those on my Whaler and have serviced lots of other ones. I don’t think those temps are too far from the norm…..yet.

That being said, there are three things those motors like to do…..eat impeller hubs and fill the water jacket with junk, especially in salt water. Also, rot through the inner exhaust cover and dump water off before reaching the top cylinder. If the impeller is two years old or older, I would definitely change it as a precaution. Also, you may then note it runs a little cooler because the new blades of the impeller will be a little more efficient.

If your motor is one that has the crank seal on top of the drive shaft and not an o-ring, order the seal with the impeller, ’cause you will find it’s probably shot, when you pull the gear case.

If your motor’s tell tale hose comes off the top of the block, you’re good. If it comes off the center of the water jacket cover, you should get a longer hose and route it to the top of the block, then down and out, with a loop at the top. That way, you’ll know you have water to the top of the block or there’d be no water coming out.

I think you are okay to run for now with a new impeller to be safe; but I would definitely keep an eye out for the temps getting any higher than that. If they do, you’ll have to go after the water jackets.

Long live American manufacturing!