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!

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.

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.

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-MARINE.../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.

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

Wanna come strip bottom paint? :beer:

I cut an old garden hose and it slid right on the intake tube. I flushed it a little bit with the hose bibb hardly on. Not sure how much pressure I can put on the system.

No more Mercury Parts Express :cry:

They have this BS that you cannot order parts online through. www.mercurymarine.com/parts-and-accessories/parts-catalog/