If you have a brass raw water pump (Mercury) read...

[Go Aweigh2452]

Monday I changed out the antifreeze and rebuilt my 9.9 carb. I started the 6.2 up to make sure my spark plugs, rotor and cap were done right. She started on the first touch of the key. As she started to warm up the water temp suddenly went to 205 and I shut her down. It was either an air block from the antifreeze change or the impeller. The 6.2 needed its impeller changed out. Thought that would be simple (Not) because its hidden behind the Gen Cool Fuel II system... and then the bad news...

So much for having a brass raw water pump. The impeller is in good shape so I can assume I had an air block in the engine from changing out the antifreeze and that drove the temp up to 205*. Getting back to my brass pump, it is significantly worn where the impeller has grooved the inside of the pump to a point where my Kitsap Marine repair shop suggests strongly to replace the entire pump ($658+). The problem with that is the factory pumps are significantly back ordered and I have to wait at least two weeks (after 1 May) before the order will even be taken and then wait for it to be shipped...

From my understanding speaking to my Marine store rep, the brass pumps service life has been around 200-300 hours and mine has well over 400 so in that regard, I am fortunate it lasted this long. And of course, there is no plastic replacement for this pump...

So, anyone with a brass pump and more than a couple hundred hours on her, better start thinking about a backup/replacement soon...

 

[moparlvr4406]

good info....thanks :thumbsup:

 

[jason78]

There has actually been quite a bit of discussion on here about this subject lately. There are a couple alternatives to replacing the entire water pump. The new Merc pump cover (the one without air fittings for raw water cooled engines) is now plastic and has a wear plate from what I understand. I ended up installing the Stainless wear plates.

This thread has most of the latest info.

http://clubsearay.com/showthread.php/50390-Wear-on-RAW-Water-Pump-Housing-Cover-Assembly-Bravo3

 

[jason78]

Also, if your Impeller housing is in need of replacement, you may want to try this as an alternative. It also came up in a recent Water Pump thread. Of course, check for compatibility.

http://www.hardin-marine.com/p-1577...sea-pump-for-mercury-350-496-and-502-mag.aspx

 

[Lazy Daze]

Jabsco makes replacement (bronze) pumps, as well. I've never used one, but they're supposed to be rebuildable - but double check me on that. But, yeah, that sucks you gotta replace it.

 

[Go Aweigh2452]

Thanks Jason, my "problem" is that my pump has the air purge system which is a different pump then the SS one you posted. Thanks for the link.

A friend will attempt to mill the grooves out and I'll use it as a back up... Hopefully, in the not too distant future, the SS one will also have the air purge system.

 

[Jimmy Buoy]

Bummer! Your engines are "Horizon". Did any warnings sound regarding low water pump pressure or high temp's in the block or exhaust manifolds? These engines are supposed to have a "guardian" program to sense these problems, alert the captain with alarms, and reduce power to the engine... No workie??

 

[jason78]

Thanks Jason, my "problem" is that my pump has the air purge system which is a different pump then the SS one you posted. Thanks for the link.

A friend will attempt to mill the grooves out and I'll use it as a back up... Hopefully, in the not too distant future, the SS one will also have the air purge system.

Mine has the air purge system as well since I also have closed cooling. As far as I can tell the only difference between the two pumps is the cover assembly that has the air fittings on it. The impeller housing appears to be the same.

In the end, I just installed the Stainless wear plates in mine instead of the new Stainless impeller housing since my housings were fine. I guess I still don't know what part of your pump is actually grooved; the Impeller Housing, Cover assembly or both. If it is just the cover, the Stainless wear plates should do the trick.

 

[skolbe]

Now I know why after an impeller change I am still getting lower psi on one engine. Glad I read this thread. I find Merc. management and engineering thoroughly frustrating. The impeller change isn't too bad it is the chiropractic visits afterwards.

 

[Go Aweigh2452]

I am not so sure I want to mix brass with stainless inside my raw water pump. I did find out I can mount a crank shaft pump on the engine eliminating the need for belt and makes it easy to change out the impeller. As long as you have 6 inches in front of the engine, this design works well. Several companies provide them and they run about $150-200 plus new hoses so that seems a good alternative. I'll be calling my local Merc mech and ask if it is feasible and what negatives there are on this arrangement. I'll also ask about how important the air purge is... so many questions... anyway, here is a photo of the crank shaft mounted water pump...

 

[Lazy Daze]

Be careful with what company you use for that. Those companies might be very reliable, or they might not. If it's a Jabsco pump - you're good to go. I can't vouch for the other companies... whoever they might be. $200 sounds awful cheap.

As long as you have adequate room, this is perfectly acceptable and has been done on other engines (Volvo, for example) for a long time. I've considered this modification on my own boat, but the truth is that I have really good access to start with.

EDIT: By the way, just for reference, that picture (whoever's that is) you included is a bad installation. One, it looks like a brass pump - it should be bronze. Two, there appears to be nothing giving any extra support to either the pump or the hoses.

 

[dpmulvey]

I have terrible access on Saint Max and have also considered Go Aweigh's setup. I have horizons and need to research a few things before making the swap. WRT the OP's problem, contact [h=1]Coopers Marine[/h]11476 Fox Cross Rd, Ashland, VA 23005
(804) 752-5835

I bought some impellers from them a couple of years ago and they warned me of the problem. They have developed a process where they can machine the groove once or twice then they have a means of fixing the problem with an insert. It's a lot cheaper than a new pump.

 

[Go Aweigh2452]

OK, went down and spoke to the Mercury rep here in Port Orchard face to face. He said it is doable on my Horizon engine with air purge system but we'd have to seal off the access to the air purge for the original raw water pump. The other issue is the depth of the crank shaft pulley in that it is deeper than older Merc engines. I measured mine and would need a 1/4" spacer to clear the throat of the crank shaft pulley. The recommendation is to go with Johnson pumps. The bigger one they sell (smaller one retails for about $200 but can be found for less on the street). The other concern is since the original water pump will be gone, I would have to find a serpentine belt to fit and again the rep said it is possible for an Alpha 5.7, 5.0 or even the 4.3 belt to fit but will verify by measuring the size. Sooo, will let you all know when I am done researching this and verifying before posting more info on this project.

Dennis is correct, the photo is an incomplete project and I should have found one that shows the pump is secured by other than hoses hanging down.

Good catch by Dennis...

 

[dlvwill]

Agree with the Johnson Pump. Go to marineengineparts com and they have everything for the conversion. In my case it was support bracket BAR93-0573 and pump JP10-24232-1 for freshwater cooling.

 

[Jim240]

The support bearings for my pump corroded, failed, skewed and caused the shaft to barber pole out last spring... serpentine belt came off and set master alarm. My back plate had some grooves too. I smoothed them out with 0 scotch brite and used progressively finer scotch brite to I think 0000... it only took a few minutes. It worked fine last summer...

Why scotch brite? If you use the right stuff, it's non-metallic. The abrasives on many other things you might want to grab are going to imbed dis-similar metallic particles into your pump housing.

 

[Bel_Mar_Pointe]

So much for having a brass raw water pump. The impeller is in good shape so I can assume I had an air block in the engine from changing out the antifreeze and that drove the temp up to 205*. Getting back to my brass pump, it is significantly worn where the impeller has grooved the inside of the pump to a point where my Kitsap Marine repair shop suggests strongly to replace the entire pump ($658+). The problem with that is the factory pumps are significantly back ordered and I have to wait at least two weeks (after 1 May) before the order will even be taken and then wait for it to be shipped... QUOTE]

Well this hurts to read......I'm on a little golf trip with my boat on blocks at Kitsap Marine waiting for two of these pumps to arrive. They were supposed to be in this week so my boat will be ready when I return but it doesn't sound good. Both of my pumps had bad scarring/grooves on both sides of the impeller. Oh, and I have been waiting for almost a month for these pumps. Seems like a common part to be backordered for a long period of time.

 

[Skuza]

What the hell holds the pump housing keeping it from rotating? Also would t this affect the harmonic balance of the engine? I just see something locking up and a catastrophic failure over a simple thrown belt.