Water pump 2.5L Mercury
 

Running the 1994 Mercury 2.5L 200 today, and wired in a tach. I shut it off and discovered my muffs were off. Its on a stand in the garage but I have a piece of plywood on my stand for stabilty so i could not see the muffs. When I started it, the muffs were on. I put the muffs back on, and cranked it. Took over ten seconds to get water out the pee hole,and the water coming out was HOT, yet the entire time I had water coming out the two lower holes in the mid. The heads were hot, I could not hold my hand on them long, along with the spark plug zap.

I want to drop the lower and inspect the water pump. Is there anything special i should do? I have changed water pumps on Yamaha's before but never a Merc. Is it the same?

I have no clue how long the muffs were off. I would like to believe they came off when it torqued to the side when I shut it off. I have a laser thermometer but I can not find it.

Nonetheless Its getting a new water pump impeller, housing, all the bells and whistles this Friday. Also, the thermostats are not in it. Would that help or hurt it?

Who is recommended to purchase the water pump through? I was going to buy it local at Emerald Coast Marine but they are closing.

I dropped the lower, was careful to watch for anything falling, springing, flying etc. Nothing happened. Lower unit dropped right off. Got the housing off to discover a brand new looking impeller. Maybe I am paranoid after what happened. Will post pics of everything when mom gets off the computer. I was expecting a much larger housing and impeller. But like in my above post I have only done Yamahas. On the splines on the driveshaft, is it supposed to have a groove on the side of the splines? They all look too perfect to be wear. And I had a blue oily crap on the front of the mating surface of the lower unit. Based on it being blue is it two stroke oil? Also how much up and down play should I have in the driveshaft?

Pics.

Housing after i pulled it

http://i272.photobucket.com/albums/j...bracket018.jpg

Views of the impeller

http://i272.photobucket.com/albums/j...bracket019.jpg

http://i272.photobucket.com/albums/j...bracket020.jpg

You can see the blue oily crap on the shift shaft end of the lower unit.

http://i272.photobucket.com/albums/j...bracket022.jpg

Driveshaft splines with grooves??

http://i272.photobucket.com/albums/j...bracket024.jpg

had the same thing happen to me, except mine ran long enough for the alarm to go off. i bought the merc muffs withthe pin that go through foot to hold it on the intakes. i would recommend getting the complete kit, includes housing & plate. i also use mercury, not sierra or other look-a-likes.

Politely speaking,... Sierra sucks. Buy the Mercury kit...it will have everything you need and will fit exactly.

Looking at your impeller, it looks fine. There's a little wear on the spline tips, but nothing that would cause me to worry. The fact that you had water running thru the muffs is probably what saved it. Don't forget the water is the lube for the impeller, so since it was wet it didn't suffer the damage that a dry impeller would.

Yes, the driveshaft has splines on the top... they mate with the bottom of the crankshaft. No, they are not supposed to have grooves..that's wear. Nothing you can do about it except replace it, no way to repair it cheaply. But based on the amount of wear I wouldn't worry too much. There's still plenty of meat on the splines. Put a little high temp grease on them before you marry them together again. My bet is it will last longer than your engine. I'm sure that other people may disagree with me, but logically speaking, there's no reason to spend LOTS of money on a new crankshaft and driveshaft while the old one is still very functional.

As for the "t"stats, yes, by all means put them back in. You engine requires a certain temperature to run properly. Having the stats out will cause it to run cooler than it's supposed to and will, over time, damage it.

Your water pump impeller is toast. The rest is normal stuff. The Merc impeller is small compared to say my 90 Johnrude and even later model Mercs. They work just fine, just smaller. A little up and down play in the driveshaft is also normal although a little alarming to me. The lowers on these outboards are pretty darn crude.

My 2.4 tends to run warm. It will overheat with T-stats in...I've run with out for years. BUT if yours runs normal temp with T-stats then def put them in as Destroyer said

Thanks everybody. Looks like Mercury Parts Express for the water pump and t stats. Do I need to replace the lower housing? And how much driveshaft play is not good? I will mark it when i get home and see how much it is. Its around 1/8" to 1/4".

Truthfully I don't know how much play is acceptable. Not much I'm sure. I'll look in my various service manuals when I get home and see if I can find a suitable answer. I'll post it here unless someone else answers first.

Ridge? I'm always willing to learn. Based on the pictures, could you explain to me why you think his impeller is toast? I mean, don't misunderstand me, it's always a good idea to replace the impeller every year, and since he has it apart anyway, now would be a perfect time. But what is it in the pics that makes you think it's toast? Looking at the pics I can see a little normal wear on the leading edge of the vanes, but nothing that looks out of the ordinary to me. I don't see any cuts, tears, cracking or evidence of overheating. Am I looking in the wrong place? :head: