Seawater pump rebuild questions

rinker312

All,  I have a 2004 merc 5.0 MPI. engines.  This weekend I was idling around and all of a sudden had a solid alarm.  I looked around and noticed my heat guage was up.  I shut down that engine and idled back on one.  Opened hatch and noticed that there was water dribbling in near the raw water pump.  I got a closer look and it appears to be coming in from between the shaft of the pulley and the pump housing.  So from looking at diagrams, it appears there are two seals, two bearings and some sort of spacer. 

I have done the impeller kits before and that was easy, but how difficult will it be to replace the bearings and seals in these pumps?  or do I have to bite the bullet and buy a new pump?  Hoping I can rebuild as they seem pretty pricy. 

Also, when I have done the impeller kits I was always on the hard.  Can I do this in the water and just clamp a plug in the hose, or squeeze it shut with vise grips or something?  If plug, any idea what size would go in the hose?

Any help/comments are greatly appreciated.

Thanks.

DanD2

Can't help you on the pump issue but I have replace impellers while in the water. I got in the water and put a set of muffs on the outdrive with a hose attached. I made sure the hose stayed above the water. When I disconnected the inlet hose, it was only slightly dripping water. I then plugged the inlet with a piece of cut-off aluminum bat.

Lifes Good

pinching the inlet hose with locking clamps "visegrips" works great.  No leaks while pump is off during repair.  Place a towel between the hose and clamp to protect the rubber from scaring. 

Black_Diamond

Look at this too:

http://www.hardin-marine.com/p-15774-stainless-steel-gen-7-sea-pump-for-mercury-350-496-and-502-mag.aspx?skinid=6

LaRea

+1 on Hardin Marine stainless pumps.  I've been running them for a year.  Performance is solid, they look great, and they have replaceable wear plates.  Not much more expensive than the standard pump.

youstolemybeer

google how to rebuild the pump. Very easy to do it. there is also a bearing kit out there if you need it. or take the bearings to your local Grainger and they can match them for about half the price

Dream_Inn

I went to fix this seal on two pumps several years ago and the parts guy laughed when I ordered them. He said he has yet to see anyone fix it. They always come back and buy new. I ended up buying two new pumps a week later.

rinker312

yes, I am kind of thinking the same thing, that it may be better to just bite the bullet, because if I buy the parts and the housing is worn at all I am not going to get a good seal.  thinking the hardin pump may be the way to go.  Thanks for your help.

Black_Diamond

@312: the curse of the pump (not including the impeller) is the seals, if the shaft is worn/damaged a new seal will not work, there are ways to fix it but the cost/benefit is likely not there.

rinker312

I ordered the Hardin pump today. Should have it Thursday. Thanks all for your insight. 

Michael T

312, I am sure you have chosen the pragmatic path. If it's not too much trouble please take and post a couple of pictures and comments pertaining to your endeavour as all of us will face this issue. Thanks. MT

rinker312

I will document the process and post the pics.

rinker312

Here are the steps for changing the pump and a picture of the new pump ready to go on.  Sorry I didn't take more pics, but I didn't get started on this till later in the evening and I was in kind of a hurry.

1.  Remove hose clamps from the two lines going to the pump.  This can be the hardest part, but since I have replaced my impellers before I now have the hose clamps aiming the right way and easy to get at with a ratchet, long extension, and universal on the end. 

2.  Remove bolt holding the bracket to the front of the engine.

3.  Remove nut from stud that is just above the bolt mentioned above. 

4.  Remove idler pulley and this will allow you to take off the pulley bracket. 

5.  At this point the pump can be slid off the stud and out for further dis-assembly.

6.  Remove bracket and back from the old pump about 6 or 8 bolts

7.  Need a power steering pulley puller to remove the pulley from the old pump.  I rented one from Oreilly's auto parts, but any auto parts store should have one.  Pulled and then placed the pulley on to the new pump.

8.  Place oring into the groove on the new pump, place stainless plate over the oring, place gasket over the stainless plate.  I used a very thin layer of black silicone on back of the old pump that I was reusing because there was some scarring of the surface, so I just wanted to ensure I had a good seal to the gasket.  then bolted it all back together with the bracket in place.  See the picture attached.

9.  adjust your adjustable idler pulley all the way down so that you can get the belt back in place.

10.  Put the pump back in opposite of the way you took it off.

11.  Put belt back on properly.

12.  Adjust tension on belt with adjustable idler pulley

13.  I did this at night, so I waited till the next day for the silicone to dry.

14.  Ran engine for a few minutes, and checked belt tension, adjust if necessary.

15.  checked belt tension again after we came in for the day, adjust if necessary.

TikiHut2

Nicely done.

I'd add step 3a:

Take picture of belt routing as the image on the little sticker may be different. (mine certainly is).

Mike

Black_Diamond

Thanks for the follow up!

rasbury

sweet- I need to tear into mine....does not look like to tuff a job and I probably just cursed myself...my motor is a closed system so I think I have two pumps to deal with? Need to figure that out and do that and change my foot oil. Have this booked marked for this project. How much time involved once you got into it?

Dream_Inn

Very nice. One thing to add is to spray some lubricant into the two hoses before reinstalling. It will make the hose installation much simpler. You may also want to replace the blue drain plugs, as they do dry up and crack over time (or at least pull and lubricate their threads). Oh, and don't overtighten the 6-8 bolts. There is a torque on them you should go by. (I'm thinking 7in lbs?) Ras, the first time will take a couple hours. (removing hoses are a pain) Next time it will be half that. You have the same number of pumps whether you have closed or open cooling. This is one and then the engine water pump (on front of engine, no impellar to change). Oh, what is foot oil?

rinker312

Yes, my very first time replacing impellers I spent at least a half hour to 45 minutes just getting off hose clamps and breaking the hoses free (alot of cursing going on).  This time hose clamps off and hoses pulled in under 10 minutes.  I probably finished the job completely in an hour.  Hardest part was pulling the old pulley off.  Working at the boat and didn't have a vise to clamp the old pump into, so I had several friends holding on like crazy to the pump as I tried to work the puller.  Keep this in mind if you don't have a few friends around, I would have been out of luck trying to get that pulley off by myself without a vise.

I avoided touching those blue plugs since the way I winterize, I don't pull the plugs and as dream inn said I am sure mine would have cracked if I tried to pull them.  

Good luck, post back if you need any assistance.

rasbury

I need to look at the manual....so the pump on the front of the engine has no impeller? I bought one, where the heck does it go then? My closed system has a thru hull intake as well as an intake from the foot. I figure that out when I ran it with the muffs as I put the muffs on and it came out the bottom of the boat. So, do I have one pump that supplies the heat exchanger and one for the motor or is it all the same? 350 mercruizer....

Black_Diamond

As far as I know, for the Bravo III you have the raw water pump on the front of the engine, it pulls the water from the outdrive.  Then you have a circulation pump like a water pump on a car (where the belt driven fan would be mounted), that moves the water in the engine itself and though even your heat exchanger.  I'm not sure about another intake thru the hull besides the one for the genset, A/C and toilet.

rinker312

I'm no expert on closed cooling systems but here goes 

well to the best of my knowledge the pump on the front of the engine is just like an automotive water pump and that pump is probably what is circulating your engine coolant through the engine and through the heat exchanger to cool it. You can't really replace the impellers in these units to the best of my knowledge. I have always just had to replace the whole pump if they go. The impellers in these pumps are usually brass or cast iron or something. 

You should then have a raw water pump. This is the pump that is in my pic and is the pump that you can replace the impeller in. This pump is located toward the bottom left of your engine. This pump will pump in seawater and pass it through your heat exchanger to cool your engine coolant. I thought that on all the bravo applications the seawater came in and exhausted through the transom. But perhaps you have something custom going on.  

First find your seawater pump that looks like mine. Then follow the top hose this is the intake. You should be able to see if this leads to the transom or to a thru hull fitting. Either way this is where you water comes in at.  The bottom hose should go to your heat exchanger and I believe it may also go to your exhaust system for cooling it. Even on closed systems I believe raw water is used to cool the exhaust. 

Again I'm no expert on closed cooling but hopefully this helps you track some stuff down.  If I was incorrect on any of this someone can straighten me out

Thanks. 

rasbury

I will book mark this section and come back to it.......thanks all!

Michael T

Well done 312! Superb, sequential explanations - helpful to all! MT 

rasbury

so what does that pump cost?

rinker312

Can't remember exactly, but with shipping and all, it was right around the 450 mark I believe.  I believe the merc pumps are in the 300 range, so I figured it was well worth the couple extra bucks to go with the upgraded HARDIN pump.  Particularly once I started reading about how many others have experienced the same problem  with the merc pump, and although I read many stories about people rebuilding them, I often read that a few months after the rebuild, they ended up having to buy a new pump anyway. 

rasbury

I'd say that pump really works hard....might be worth the upgrade but they are expensive!