Sea Water Pump Cover - Question

[DHutch]

Hello IBoats Members

Question regarding the Sea Water Pump Cover on my 350 Mag Ski 1995 engine.
I'm trying to source a new O-Ring seal for the cover.
Is this available either through Mercury Quicksilver or Sierra Marine?
What is the part number?

I noticed last season a slight water leak from the bottom of my Sea Water pump while running - just a few drops per minute. Barely noticeable and certainly doesn't accumulate enough to turn on the bilge pump.

Last fall I removed the entire Pump. Just recently got around to inspecting. The impeller is perfect, wear plate is good. I figure just a new O-Ring replacement on the bottom of the plastic cover maybe required.
Or any other suggestions / recommendations?

Can I order just this O-Ring?

Thx
Hutch

 

[Scott06]

Hello IBoats Members

Question regarding the Sea Water Pump Cover on my 350 Mag Ski 1995 engine.
I'm trying to source a new O-Ring seal for the cover.
Is this available either through Mercury Quicksilver or Sierra Marine?
What is the part number?

I noticed last season a slight water leak from the bottom of my Sea Water pump while running - just a few drops per minute. Barely noticeable and certainly doesn't accumulate enough to turn on the bilge pump.

Last fall I removed the entire Pump. Just recently got around to inspecting. The impeller is perfect, wear plate is good. I figure just a new O-Ring replacement on the bottom of the plastic cover maybe required.
Or any other suggestions / recommendations?

Can I order just this O-Ring?

Thx
Hutch

Best to search on this site by serial number but I think 13 is waht u are looking for

https://www.marineengine.com/parts/mercruiser-sterndrive-parts/350-mag-ski-gm-350-v8-19911996/0d505450-thru-0k040399/sea-water-pump-assembly

 

[bbook83]

I would suggest a careful examination of the plastic body for cracks and also confirm that you did not have a leak at either the in or out hose. Sometimes the impeller is perfect till it is not. My experience with that pump on the same engine has been to change the impeller every 100 hours.

 

[DHutch]

I would suggest a careful examination of the plastic body for cracks and also confirm that you did not have a leak at either the in or out hose. Sometimes the impeller is perfect till it is not. My experience with that pump on the same engine has been to change the impeller every 100 hours.

Thanks for the feedback Scott06 & bbook83.

I have inspected the housing for cracks - its good. Also last season I thoroughly inspected all hose connections & trans oil cooler. Everything was tight & dry. The water I saw dripping was definitely at the bottom of the pump cover - leaking between the cover & wear plate.

 

[alldodge]

Don't have your motor serial number but O ring should be item 3
https://www.mercruiserparts.com/bam/subassembly/31601/4835/170

 

[Bt Doctur]

in some cases its the front seal that is leaking

 

[DHutch]

in some cases its the front seal that is leaking

Update & requesting some feedback - sorry for long narrative below....

I did source from Mercury the o-ring that goes under the plastic impeller housing. I removed cover and installed new o-ring. As I indicated in early posts, the impeller is perfect, wear plate looks good. Figured a new O-Ring replacement on the bottom of the plastic cover maybe required to correct a very small leak I noticed from the bottom of the Sea Water pump when engine is running.

When reassembling and using the new o-ring, I noticed one of the six holes in the pump for the cover is stripped. My Sea Water Pump is the style with the V groove pully. The bracket holding the pump to the block is bolted to the back of the pump via four longer screws. It's one of these threaded holes in the pump that was stripped. Looks to me a previous mechanic did not use long enough screws for this bracket, the nuts for these four holes only have a couple threads holding. I used longer screws. Hoped that tightening these with the longer screws & the nuts for the bracket would be enough to seal the cover properly. Specifically, the one screw that has the stripped hole.

I installed the Sea Water Pump last night and tried a start-up using a "fake lake" water feed on the bottom of the hull (Boat is a direct drive ski boat).

Now I'm not getting any water pumping out exhaust. Just a slight bit of water when I burp the throttle. No water coming from the exhaust while idling.

I checked all hoses & clamps - they are tight.
I checked & confirmed I have correct orientation of i/p & o/p hoses on the pump.
FYI - I used this fake lake set up last spring and had no issues - water poured through the transom exhaust while idling.

What do you recommend I look at now? Any suggestions?

Thanks
Hutch

 

[alldodge]

The inlet hose goes on top

The one hole is not stripped out, it's made that way and should have a longer bolt with lock washer and nut. Holds pump to bracket

 

[dubs283]

The pump shaft/bearing housing should have five threaded holes for the bolts securing the plastic impeller housing. Often one or two bolts will not extend beyond the shaft/bearing housing because the bracket that mounts the pump to the engine does not have holes drilled for them. There should be at least three bolts with enough threads protruding to mount to the bracket with the proper orientation.

Did you ensure the small quad ring was in place at the shaft/pump housing prior to installing the wear plate?

The housing is marked for input/output hoses based on engine rotation, probably worth a double/triple check

Good idea to check for any blockages before and after the sea water pump

Fake a lake works fine if the seal is good between it and the hull. Doesn't take much for the pump to loose prime if the fake a lake isn't set tight and straight. Best to orient the garden hose inlet to flow directly through the intake grates when setting it to the hull

 

[DHutch]

The pump shaft/bearing housing should have five threaded holes for the bolts securing the plastic impeller housing. Often one or two bolts will not extend beyond the shaft/bearing housing because the bracket that mounts the pump to the engine does not have holes drilled for them. There should be at least three bolts with enough threads protruding to mount to the bracket with the proper orientation.

Did you ensure the small quad ring was in place at the shaft/pump housing prior to installing the wear plate?

The housing is marked for input/output hoses based on engine rotation, probably worth a double/triple check

Good idea to check for any blockages before and after the sea water pump

Fake a lake works fine if the seal is good between it and the hull. Doesn't take much for the pump to loose prime if the fake a lake isn't set tight and straight. Best to orient the garden hose inlet to flow directly through the intake grates when setting it to the hull

 

[DHutch]

Hi Alldodge - actually with my pump, the two hose fittings are orientated horizontally. So my inlet hose from the water pick-up is on the starboard side. This was labelled as RH out. My engine is 350 Magnum, regular LH rotation. I actually did switch these around and obviously had no affect.

Hi dubs282 - yes you are correct - there are 5 bolts total. I believe 4 are used for the bracket - going by memory from last night.
When I did reassembly, yes I installed the small ring. I believe this was installed under the wear plate - thus its between the plate and the pump housing that contains the shaft & bearings. Is this correct?

Question - how tight should these 5 bolts be? Can too tight cause this issue? Just an FYI - no water was leaking in the bilge when testing last night - did not see water leaking through any fitting of at the pump.

I did check for blockage before the pump - was good I thought but will double check.
Will also check after the pump - I had no issues in the fall before winterizing except for the original small leak at the bottom of the pump.

Hutch

​

 

[DHutch]

Hi Alldodge - actually with my pump, the two hose fittings are orientated horizontally. So my inlet hose from the water pick-up is on the starboard side. This was labelled as RH out. My engine is 350 Magnum, regular LH rotation. I actually did switch these around and obviously had no affect.

Hi dubs282 - yes you are correct - there are 5 bolts total. I believe 4 are used for the bracket - going by memory from last night.
When I did reassembly, yes I installed the small ring. I believe this was installed under the wear plate - thus its between the plate and the pump housing that contains the shaft & bearings. Is this correct?

Question - how tight should these 5 bolts be? Can too tight cause this issue? Just an FYI - no water was leaking in the bilge when testing last night - did not see water leaking through any fitting of at the pump.

I did check for blockage before the pump - was good I thought but will double check.
Will also check after the pump - I had no issues in the fall before winterizing except for the original small leak at the bottom of the pump.

Hutch

​

Update as of 5pm today - checked all hoses and T-stat housing for blockages - found none. Figured I would try the fake a lake start-up one more time.
This time paid more attention to position of the fake a lake garden hose inlet with the water pick-up. Success.

Boat is pumping water fine. Reaches 160F in approx 5 mins, than drops a few minutes briefly and back to 160F. Does this cycle every couple minutes or so.

The only thing I noticed that we will need to monitor was that the starboard exhaust riser was considerably hotter than the port side. And actually the port side was cool to touch. Both exhaust tips on the transom are dumping equal amounts of water. I think water testing is the true test next.

Thanks for the suggestion regarding the garden hose inlet with the water pick-up.

hutch

 

[alldodge]

The only thing I noticed that we will need to monitor was that the starboard exhaust riser was considerably hotter than the port side. And actually the port side was cool to touch. Both exhaust tips on the transom are dumping equal amounts of water. I think water testing is the true test next.

That is not an issue, one side will always be cooler then the other on a hose. Will also happen in the water but not as noticeable