Another Leaking Pump ....

[rardiH36]

The repair to my 2QM20 engine integral anti-freeze coolant pump leak that I queried the forum about a couple of weeks ago looks to be successful. Thanks for the forums' input.

But as luck would have it, while I was visually observing that the fix was successful, I saw that the externally mounted raw water pump also now is leaking through the weep holes.

Very irritating because only 2.5 years ago I bought and installed a brand new pump. Now only 150 hours later it has failed. (And no I did not tension the belt too tight!)

Has anyone attempted a repair on the raw water pump? It's a Jabsco 2760-0003.

Assuming that the bearing is still good, appears that I will need two seals. At a minimum. I kept the previous pump, so I do have one to experiment on.

Any other alternatives? Is it possible to move the raw water around with an electric pump?

 

[seadaddler]

Do a search here or on the web and not really hard to rebuild just need good info for first time
and try here or youtube.
I did mine but not a Jabsco.
Nick

 

[Alctel]

Did mine a while ago - not too tricky.
Manual is here http://www.pumpagents.com/pdf/JabscoPumps/2760-0003.pdf

I feel another electric pump would just complicate things

 

[rardiH36]

Alctel:

Once again thanks. What parts did you replace for your repair?

Update to my status: After I made my opening post to this thread, I also located the two page instruction/technical manual that you linked to. It assisted me to breakdown my original older pump which I had brought home to my garage work bench. (My 2.5 year old newer and leaking pump is sill mounted on the engine.) I discovered that restoring my original older pump would require a major rebuild with all new seals and a new bearing -- which no longer rotated smoothly. Also, the shaft was quite scored at the location it rotated through the #14 seal. Upshot: Probably almost economically equivalent just to buy a new pump rather than attempt a repair!

In respect of my 150 engine hours newer-but-leaking-pump, I am expecting (hoping is more like it!) that repair will only require replacement of parts #14 (seal) and #15 (o-ring). These do the duty of keeping the water inside the impeller casing side of the pump. Probably the seals and the bearing on the pulley side of the pump are still in good condition. So my first attempt at repair will be not to press out the shaft. Instead I will just carefully remove the old #14 seal and #15 o-ring and insert new ones. The parts have been ordered.

 

[Alctel]

Just the seals, same as you are getting.

Surprised it's leaking after only 150 hours though - you may get lucky and just have to reseat the seals.

 

[rardiH36]

Thought to update my original post about the 2QM20 raw external pump prematurely (only 150 hours new) already leaking. I now have installed a new seal. But the pump was still leaking through the weep hole.

But really not much compared to previously.

After the pump repair, I noticed also that the volume of seawater being "spit" out along with the exhaust stream looked a bit weak. The exhaust elbow is quite new. So unlikely blocked.

The next possible culprit was the external bulkhead mounted heat ex-changer. Upon removing it and opening the end plate, I saw that over the last 6-7 years the decomposition residue of the zinc anodes had 90% blocked the raw water tubes on the intake side. So maybe the pump was trying to push against a restriction. And the increased pressure caused seawater to migrate through the pump seal?

Going forward, I now have modified the original design so that the zinc no longer extends into the tube intake area. But that the zinc will still provide protection.

I always have been mystified why an externally mounted heat exchanger even needs a zinc. The exchanger is not bonded all to any other metal item. It's only connection are via the rubber hoses. Yet the zincs deplete over a short period of time into mush. Mystery to me.

 

[All U Get]

I always have been mystified why an externally mounted heat exchanger even needs a zinc. The exchanger is not bonded all to any other metal item. It's only connection are via the rubber hoses. Yet the zincs deplete over a short period of time into mush. Mystery to me.

Salt water carries the current.

All U Get

 

[Jim Legere]

...I always have been mystified why an externally mounted heat exchanger even needs a zinc. The exchanger is not bonded all to any other metal item. It's only connection are via the rubber hoses. Yet the zincs deplete over a short period of time into mush. Mystery to me.

The heat exchanger itself is a soup of metals - stainless steel, brass, bronze, copper - so even if isolated from the cast iron engine, an anode is still a good idea. That said, I went years without one and seemingly caused no problems (I didn't realize that it was even supposed to there- doh!). When I rebuilt the Sendure exchanger two winters ago, I installed the pencil anode. I will check it, and likely replace it, this spring. BTW, Mainesail's web site has a great photo essay on rebuilding a heat exchanger.

 

[rardiH36]

Salt water carries the current.
All U Get

Yes, that is what I also sort of recognized. But still I can't get my head around why is it that our bronze through-hulls, that often (or maybe even preferably) are not bonded, have lasted 20+ years and still when scraping on each haul-out still are showing good yellow metal rather than the dreaded "pink of death".

Between outings, the salt water in my heat exchanger intake chamber does mostly migrate back down towards the pump. I know this because when I change the zinc, no salt water drains out of the zinc pencil fitting.

Maybe as Jim Legere observed a zinc is required also because of several different metals. Add to that just a smidgen of salt water hanging about. And then a heat exchanger is really a wonderful electrolysis incubator.

 

[rardiH36]

When I rebuilt the Sendure exchanger two winters ago, I installed the pencil anode.

Jim:

Thanks for the reminder about Mainesail's heatexchanger tune-up page.

So what was needed for your Sendure rebuild a couple of winters ago?

My Sendure 2550 was in a sorry state when I bought my boat in 2007. Exchanging fluid between the raw water and anti-freeze. To troubleshoot, the radiator shop, which also specialized in heat exchangers, de-solderered the end cap on the side opposite the bolt removable end cap. The baffle into which the tubes are spot welded had several micro holes in it. At first the shop declared the exchanger not repairable. But when I noted that the tubes themselves looked great, I suggested that the tech guy flood the damaged baffle with a layer of liquid solder. He did. It worked. So far the repair has held. But I am anticipating the need for a new exchanger at some point.

Attached is a picture of the mod I made so that the zinc pencil remains outside of the baffle area. Also provided room for a longer pencil zinc. Before I needed to cut the zinc down to all but about 3/4". Otherwise it wouldn't fit into the heat exchanger chamber. The union in the mod is stainless. Checking with my ohm meter, continuity between the zinc pencil casing and the heat exchanger body is good. I will check in a few months how the pencil zinc is faring down in the rabbit hole.

 

[rardiH36]

Well, my attempt to repair my leaking Jabsco 2760-003 pump with a new water seal and o-ring didn't succeed. Taking it apart again, when looking at the shaft and feeling it with a metal probe (the shaft still in the pump), I noticed that it was quite scored at the point the water/oil seal was placed. I have done a Rube Goldberg work-around so that the seal/shaft contact will be further up the shaft; i.e. in virgin territory. I will install the pump tomorrow. I have low confidence of success. Fortunately only a 15 minute task. If it still leaks, then a new pump it will be. ~$325-350. But almost the same cost as purchasing the parts for a major rebuild. Which also entails the risk of the repair tech (me) botching the job.

 

[rardiH36]

The unconventional repair to the leaking raw water pump I made looks to have worked.

I don't use the engine except for about 15 minutes out and15 minutes in. So if my repair doesn't hold, leakage over the short time span is unlikely to sink the boat -- should be confined to the drip pan underneath the engine. I will make a point of checking the drip pan after each outing to verify all is still good.