Water pump 2.5L Mercury

jasoncooperpcola

jasoncooperpcola

God
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

bracket018.jpg


Views of the impeller

bracket019.jpg


bracket020.jpg


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

bracket022.jpg


Driveshaft splines with grooves??

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".
 
jasoncooperpcola 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".
Click to expand...

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.
 
RidgeRunner said:
Your water pump impeller is toast.
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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:
 
There is cracking very slightly where the vanes curl over. You can see it in the pics, i can get a closer pic too. That may be what he saw. I opened the housing expecting to find bits and pieces of an impeller. The driveshaft has about an 1/8" maybe a little under that of play. Also has side to side play? Is that ok?

Back to bottom paint stripping!
 
draglink said:
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
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On some mERCS taking teh t-stats out can burn one up in a hurry. The poppit valve assembly must be working for the cooling system to work, otherwise the stats can't work. And that impeller is done. The impeller vanes need to stick straight out as that is how they work. These pumps are a displacement design where the impeller fins move in and out to compress the water out and pull the water in. Once the impeller vanes get laid over like the ones pictured, it is no longer pumping much. This is most important at high RPM's as the vanes need to move in and out rapidly. And the MERC impellers are a tall but short vaned design as they are a high pressure design meant for MERCRY's poppit controlled cooling system whereas other engine manufacturers used a high volume design with longer impeller vanes that aren't as tall.
 
jasoncooperpcola said:
There is cracking very slightly where the vanes curl over. You can see it in the pics, i can get a closer pic too. That may be what he saw. I opened the housing expecting to find bits and pieces of an impeller. The driveshaft has about an 1/8" maybe a little under that of play. Also has side to side play? Is that ok?

Back to bottom paint stripping!
Click to expand...

If there's any cracking then it's toast. Sad to say, looks like it had a lot of life left in it.
 
I did not know that Ferm. I am buying a new complete water pump. The old one is going in the box for a spare. No wonder it never seemed like it was pumping enough. Now that I look at it, the Merc impeller is tall. I did notice the housing is offset from the driveshaft and wasn't someone on here asking about that? Thanks for the info Destroyer and Ferm. Does Merc Parts offer a complete water pump kit or will I have to pay more for each piece?
 
Also the thermostats were shot. I took them out about a month ago when i found they were broken. I run the motor on the weekend for ten minutes, so I hope nothing is hurt.
 
phatdaddy said:
jcp, not sure what motor you have, so you,need to go by model #, but this is the kit for my 94 150.

http://www.amazon.com/MERCURY-MARINER-OUTBOARD-ENGINES-46-96148A/dp/B001HBUSK8

the merc part # is 46-96148A

also, like ferm says, if your going with new t-stats & water pump kit, i'd get the poppet valve kit also.

i change all of those once a year in mine.
Click to expand...

Ok no problem. I had the poppet valve off already and it was on the list just below the thermostats. While i have the lower unit, would it hurt to flush the engine thru the thermostat holes and the poppet valve hole with the hose?
 
I don't think it would be a problem, but i'd wait for a grown-up to give you a better answer. i know when i have mine apart i made an adapter so i can hook a water hose up directly to the water intake tube and when i pull the t-stats i flush out those holes, but hever have done the poppet valves.
one thing i have found out is t stats open a different temps. over the years i have a coffee can full of old ones( why i keep them, i do not know). i threw them in a pot of boiling water to open them up & while they were open i stuck a piece of fishing ling in each one and let them cool. then i took them and hung them in a pot of cold water and started heating it up. i used my laser thermometer to check temps and some started dropping @ 120 on up to 180 degrees. now when i put new ones in, i check them to see if they are opening about the same.

sometimes i think i have too much free time
 
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