formula31

The big headache is getting the pump out of there. You have to get the hoses off (not easy) (write down which hose goes where) and then remove the bracket from the block. Take the pump out bracket and all. Then take lots of pictures so you know how the bracket goes back on the pump and take it apart. You will need new gaskets, end plates and an impeller. If its a newer one I think the end plate where the hoses hook up is part of the body. If the impeller is missing vanes, find them. Sometimes they go right to the oil cooler, another fun thing to get at. I hope you dont have twins, then its a lot more fun (lots of swearing).

bayou outlaw

djm, I had the same problem as you when I fired up my engine a few weeks ago after the winter layup. Problem was that I used one of those winterizing kits that you put the anti-freeze in and let it gravity feed to the muffs on the outdrive. Had good water flow at the time, but all I was doing was burning up the impeller the whole time. Bravos really need a good water supply. Long story short, ended up changing my entire pump housing it had worn so badly. From now on I will drain the entire system and be done with it. You can change the impeller, it's not too bad a job. Andy

Griff

If you go to www.mercruiserparts.com you should be able to look up your engine and see a diagram of the raw water pump with the impeller. It will make it easier to understand what everyone is talking about. It is a pretty simple job.

BajaBoss252

The rebuild kit is about $75 at the above mentioned website. It's not that hard to do. You will probably have to pull the fuel pump off (2 nuts, but it's in a plastic case that pulls off) and push it to the side to get the water pump. I didn't take the bracket off when I did mine. I just took all the nuts holding the pump to the bracket off. I think there about 5. Pull the water lines and out it comes. Oh yeah, you have to take the belt off first..

Good Luck!

cigarette

this job is really simple, if you have room to work in your engine compartment, when you put the impeller back in the housing make sure the rotation is correct so when you start up the impeller doesn't have to reverse direction. use some dish soap to lube impeller for start up.

djm

Thanks for all the replies, love this board. I'm confused though, how many water pumps are there? I thought two, one that is bolted on the front of the engine, ran by the serpentine belt, and pushes water through the block and exhaust. The second is the one I burned up I think. It is located on the starboard side really low and has two hoses going to it, it pulls/pushes water from the drive, not sure what drives it though. Both of these pumps have an impeller. Does that sound right?

djm

Posted too soon before. I checked the diagram (Thanks Griff) and found the sea water pump but don't recognize it. Here's a link to a pic of a 502 cooling system. Hose 11 and 12 connect to what they call a sea water pump but looks different than what is driven by a belt. What gives? Is it the same thing minus the pulley.

http://www.mercruiserparts.com/Show_...88%2E2L+MPI%29

cigarette

that is the seawater pump without the pulley, click on seawater pump and it gives you the break down of it, empeller, pulley, etc.

rod

Cignificant

djm, the "pump" on the front of the block is a water circulator pump. It doesn't do a whole hell of a lot on a marine engine - a lot of people replace them with crossovers to get more HP. The impeller is in the sea water pump.

bimini run

OK - just so I have this straight. On newer Bravo I's (98 7.4L), there is NO impeller in the outdrive? The impeller is in the sea water pump? I was going to pull my drive to change this. I guess I don't have to???