Engine seawater pump failure

fdough1

fdough1

New Member
Jun 21, 2015
63
Havre de Grace, Md, United States
Boat Info
2007 Sea Ray 340
Engines
2XMercruiser 8.1 Inboard
2007 sea Ray 340 with 8.1 horizon engines. Yesterday about 20 minutes into a run out, the smart craft goes off and pulls back to idle. I had the engines shut down within a few seconds. Limped back in on starboard engine (that was a fun parking job, thank the lord I have a bow thruster).

Opened hatch and found this mess. Serpentine belt was shredded and pump pulley was laying in the bilge.
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Removed pum. And found I impeller intact (I needed to change it this season) and pump housing was scored at either end of the impeller. The inside of the housing was fine.
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So the pump looks to be toast but my question is has anyone seen this type of failure? Should it be blamed on old impeller?

Thanks


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Common, another down side of the soft brass, the shaft assembly loosens up and walks out of the housing. Nothing to do with the impeller
 
Merc does offer a shaft assembly repair kit but with all that heavy scoring you've got, I'd say it's junk.

Wondering how many hours on it ?
 
OK...so I am left with buying an all new merc brass pump or...I have heard of two options:

1. few threads that talk about the Hardin SS pump... does anyone have experience with this option
2. a repair plate that installs on the impeller housing back half of the pump (side of the pump without the impeller)
 
I installed Hardin pumps beginning of last year and have over 100hrs on them now with no problems. It is hard for me to say how much better they are I only have 100hrs on them and my old pumps (housings) had almost 300hrs on them so when I installed the Hardin pumps I got alto more suction, they seem to prime much better and pump more water but that could have just been the result of older pump housings vs new pump housings. Overall I am glad I went with them.
 
Wow Wee, must have been water pump failure weekend. Mine day was Friday night. Like the OP I was just cruising along minding my own business when the Vessel View started wailing. As I was backing things down the indication was that the starboard engine was overheating. Lake Michigan was "calm to glass" so after I got the Admiral to take watch I headed into the engine room. Like Fdough, I was greeted with the serpentine belt on the floor, water coming out of the pump housing and my pulley shaft and bearings wedged under the engine.

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We were 5 miles from our destination where we were meeting friends at for a night on the hook so I just idled in on the port side alone. The following morning I stated to investigate. Unlike the pump in MasterFab's thread my housing has no snap ring. No snap ring groove, no snap ring, nothing to hold it in the housing except the press fit of the outer shaft seal.

I sat there dumbfounded as this was the most ridicules design I have seen for quite some time. So I got on the phone and googled my pump and found that in the expanded view it did indeed show no snap ring, nothing. Are you kidding me as I started to try and figure out a way to hold it in there. I ended up drilling and taping a 10-24 thread in the housing right where the tolerance ring sits. I then installed the pulley and shaft assembly into the housing. With the pulley and shaft assembly back in there I then put a stainless steel screw in there with about 1/16" sticking in the the gap where the tolerance ring is. Worked very well and on the way home I just kept checking both temp gages on that side till we were home.

Not sure if I am going to work on it further or do a preemptive repair to the other side yet. I still can't believe that design.
 
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I've replaced one of those for a customer...also thought of a set screw to hold it in but, wasn't my boat or money so, OEM installed a new one.

Much prefer the older design one piece plastic housing with the stainless wear plate that I have on the old 7.4L's but, I digress.......
 
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Gary Hill said:
BTW I meant to ask, has anyone seen these pumps without the snap ring?
Click to expand...

No snap ring on mine. Rebuilt it a few years ago when the seal to the bearings failed and seawater killed the bearings. All I did was put some blue lock tight on the outer "cap" before tapping it in place. No further issues. It's possible that there isn't much fore or aft pressure on the pulley since it's aligned with the other pulleys which may be the reason it can do without a snap ring.
 
Gary, did you look at the pump housing where the shaft goes through it. The hole was egged out which led me to believe that shaft was wobbling around in the housing while it ran.
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Good Morning All,

Jimmy I agree that the fore / aft pressure should be very limited and as you say the belt should help keep it in there. I still believe that a $25,000 engine (or more, I'm guessing) with the weakest link being a piece of rubber, should at least have a reasonable design around said rubber.

Fdough, I did inspect the inside of the housing very carefully while I was in there. Had my "tiny mirror on a stick" in there as well looking for signs that I needed to be concerned further. I did not see any wear anywhere (that's a tongue twister).

I will be going to the boat tonight to inspect things again as we are leaving for Ludington MI Thursday and I want things to be "ship shape" before we leave.

Happy Fourth to All, God bless these United States.
 
The "out of round" holes are the worn seals. They are replaced during the rebuild process, so this is not a concern. However, if one of the bearings seized, it is possible that the housing may have been scored as the bearing outer race spun within the housing. This is an abnormal condition, and isn't likely, but is possible. Be sure to examine the housing carefully, and make sure the replacement bearing/shaft assembly fits properly during reassembly.

Dale
 
New (same mercruiser brass) pump installed and working. Only issue is water pressure at idle is .1-.3 psi. I changed the impeller on starboard engine and it reads 1.7 psi at idle (did read .2-.5 psi before change). Clearly water coming out of port exhaust, but I would have expected higher pressure.


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fdough1 said:
New (same mercruiser brass) pump installed and working. Only issue is water pressure at idle is .1-.3 psi. I changed the impeller on starboard engine and it reads 1.7 psi at idle (did read .2-.5 psi before change). Clearly water coming out of port exhaust, but I would have expected higher pressure.
Click to expand...

Have you run it on plane yet? If it does not get close to 7 psi, Guardian mode will probably kick in...
 
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