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Water pump, fresh water side... Rebuild able or replace the whole assembly?

1rider

New member
I have figured out that an overheating issue I have is due to my belt driven water pump not pushing water. The unit appears to be sealed up pretty good so I am not sure if it can be serviced or not? Is the impeller inside the unit on a key way or something similar that could be repaired?
 
I have figured out that an overheating issue I have is due to my belt driven water pump not pushing water. The unit appears to be sealed up pretty good so I am not sure if it can be serviced or not? Is the impeller inside the unit on a key way or something similar that could be repaired?

Year of Motor ???
Do you know the pump type?
Is the pump actually drawing water? Make sure the inlet on the boat hull is not jammed up with a plastic bag or some other debris.
Are you sure it is the pump and the belt is not too loose?
When was the last time the impellers were changed.?

There are parts available for most freshwater pumps and it is no big deal to change it. The easiest way is to remove the pump from the mounting plate, normally two bolts, remove the clamps from the hoses, pull the hoses off and when you have the pump out, remove the four screws on the back of the pump and pull the impeller out and replace it.
I am sure there are videos on You- Tube on how to service a belt driven marine engine water pump

I just changed my impellers on two Sherwood pumps, (twin 350's), and it took me about two hours..(with V-drives...... that port engine pump is a %^$&*^ to get at)

Good luck:)
 
I apologize for not providing more info. The engine is a 2006 6.0 MPI.
The raw water pump is new and working perfectly and the boat is not in the water. I have the engine manual and a parts manual and no where does it show being able to open up the assembly, it is sold as an entire assembly.

So I made sure the system was full of water to test the belt driven water pump. With the system full I disconnected the outlet side of the water pump. I then started the engine momentarily to see if the pump would push the water, nothing. I think this is the reason for my overheating. Thoughts?
 
It was full before I removed the hose on the delivery side of the pump. In addition I opened the degas bottle and topped off the system until it came out of where the hose was.
 
I have figured out that an overheating issue I have is due to my belt driven water pump not pushing water. The unit appears to be sealed up pretty good so I am not sure if it can be serviced or not? Is the impeller inside the unit on a key way or something similar that could be repaired?

If you are talking about a belt driven sea water pump, many of our sea water pumps offer re-build kits.
The impeller will be either keyed or splined to the shaft.

Is your engine Raw Water cooled, or do you have a Closed Cooling system?
Either way, have you burned or disintegrated an impeller recently?
If so, did the impeller vanes come apart, and were you able to retrieve all of the pieces?
If so, and you weren't able to retrieve the pieces, they may be restricting sea water flow somewhere in the sea water path, in which case you'll want to pull things apart and look for these pieces.




Now, if you are asking about the GM front engine mounted pump, many call this a "water pump". Technically, this is an "Engine Circulating" pump.


If your engine is Raw Water cooled, this must be the Marine version w/ the special ceramic shaft seal, and w/ a bronze or SS impeller.

If your engine was equipped with a Closed Cooling, and was older, you could use the Automotive version, but not for a 2006.

You can find companies that will over-all these. In our city, Friction Supply Companies will do this, but I think that you'll find it cost effective to simply replace it with a new Marine version.

******************************

If you are tired of the belt driven sea water pump blues, consider a change to the crankshaft mounted pump.
No more difficult impeller access, no more belt tension side load on bearings, super easy impeller removal, etc.

This is a Johnson F5B-9 pump. The F6B-9 is the larger volume pump.
The FB5-9 can be found on sale for as little as $150, or so, complete with new impeller.


This conversion does require adequate space in front of the engine.
The pump flange bolt pattern should match the GM SBC. That's what these are designed to work with.

Here's a late model Mercruiser 6.2L Horizon with the conversion.
Granted, he could have made a better selection with his hose and hose routing, but his system is working flawlessly.


Just a thought!




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The engine is fresh water cooled.
No impeller burn up has occurred.
yes, I am refering to the engine circulating pump. I just checked my records and the engine is 2007 6.0.
So is this part repairable if it is on a keyway or similar?
The cost for new after a quick search appears to be about $300.00 +.
 
The engine is fresh water cooled.
The term "fresh water cooled" is sometimes a misnomer... since there is nothing fresh about Ethylene Glycol and H2O.... IMO.
Are you saying Fresh, as in River/Lake water, or Fresh as in a Closed Cooling system????

No impeller burn up has occurred.
yes, I am refering to the engine circulating pump. I just checked my records and the engine is 2007 6.0.
So is this part repairable if it is on a keyway or similar?
The Bronze of SS impeller is a press friction fit onto the shaft.

The cost for new after a quick search appears to be about $300.00 +.


Now.... before I suggest the wrong circ pump, you say 2006 6.0 MPI.
If this is the later generation GM V-8, then it won't be of the same SBC family.

However, if it is of the same generation, it would be a 6.2L I believe, in which case this may work for you;
Here's a circulating pum via MichiganMotors. $80 + shipping.

Fits GM V6 & V8 small block engines with steel and/or composite timing cover and made for standard rotation and reverse rotation engines (bi-directional).



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Thanks for your help. The 2007 6.0 MPI 366 cu. in. Engine has a closed loop cooling system. I am refering to the pump that is shown just to the right of the "A" arrow point in the diagram. This cooling is, as you can see in addition to a raw water system.

82bb4dec74b69296e816b0835a6991cf.jpg
 
Thanks for your help.
1.... The 2007 6.0 MPI 366 cu. in. Engine has a closed loop cooling system.

2.... I am refering to the pump that is shown just to the right of the "A" arrow point in the diagram.

3.... This cooling is, as you can see in addition to a raw water system.

82bb4dec74b69296e816b0835a6991cf.jpg


1.... OK.... now I can see what you have.
While many refer to this as "fresh water cooling", I can't bring myself to use that term. My pet peeve, I guess. :D

2.... Correct. On any engine, whether automotive or marine, this is an Engine Circulating pump.
It has taken on the name "water pump" in a misnomer fashion.

3.... Correct, and is always the case for a Marine Engine.

BTW, you have what is considered a "Full Closed Cooling" system, since it includes the exhaust manifolds.
A "Half" system would exclude the exhaust manifolds.

Elbows are typically and always Raw Water cooled, since this is where the "spent" sea water enters the exhaust mixing chamber, and is sent out with the exhaust gasses.



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I would not buy a new circulating pump until I pulled the old one off and inspected. These pumps have a cast impeller and failure mode is usually seals or bearings....but they still pump. Your "test" may not be valid since the output of the pump goes directly into the block (it is not shown on you diagram) so you were not really looking at pump output. It looks as if the return flow from the block/heads goes back into an upper channel on the pump (I never seen one like this so am not sure) before going to the exhaust manifolds and then the heat exchanger. So if that was what you looked at, and the block/heads were not perfectly full, there could be a delay before there is flow at that point. Or you could have looked at the return inlet for the bypass water which flows the other way. Whatever, the pump is unlikely (but still possible) to be the issue.

If you take it off, inspect it, spin it etc. and it looks OK you can reinstall and then get an IR gun ($50-$75 on the internet) and with that you can look at temperatures all over the system. That will usually enable you to determine the cause of the overheating. And they work great for checking the surface temp of the ocean, calibrating your wife's oven, etc. etc.
CaboJohn
 
Like John suggests, the circulating pump isn't a high failure rate item...

Have you verified the raw water is being dumped into the exhaust?
 
Just thought I would update as I have identified the problem, AIR!!


Still can't get all the air but have been able to get enough coolant mix into the system to maintain temp. Hoping it burps a little over night and I can continue to fill it up tomorrow.


The engine does not have any bleed off points and according to the manual the degas bottle is suppose to provide a place for the air to go, doesn't work so good.

if anyone has a suggestion to help get the air out, please share. Thanks.
 
If you can't get the air out after a couple hot-cold cycles and you had crud in the closed side, you might want to check the bleeder tubes to make sure they are open
 
I spend a lot of time coaxing fluid into the system. Squeezing and releasing the two hoses going to the manifolds from the front of the engines will usually move the air bubbles up to the cap so you can get a little more in. Once you have it "full" it still seems that the hot/cold cycle will manage to get a lot more in.

Keep in mind how the hot/cold works. Only while the engine heats up and comes to pressure is anything forced out. You want that "anything" to be air, and for that to happen the trapped air has to move around the system and collect around the cap. Then as the system reaches 7 psi. it will force out the air. Once the system temperature stabilizes, nothing more comes out, so you can run it all day and it won't help. My point is the first 10 minutes are important. You want some rpm to move stuff around during heat up (don't just idle at the dock). And later, as the engine cools and the coolant loses volume, pressure will go negative in the system and fresh coolant will be sucked in to replace the air.
 
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