Engine raw water leak

[Folie]

I have a small leak near my water pump">raw water pump and it is flinging around.

Engine: Yanmar 3YM20. 20HP

Becase it is flinging around-- it is hard to pinpoint. It only leaks when running. When stopped, there is a lot of wetness so I can't fine the source.

At first I thought it was from this 'T" -- plese see picture. But is not. Please--- WHAT IS THIS T for????

Attached are some pics of the pump. A presume I need to take it off and inspect it to find the leak. Any advice before I start?

Any GREAT (that is CHEAP) sources for a new pump?


Thanks a lot---- Rick


PS--- I THINK I got a video to upload which shows the water flinging around!

[markpierce]

The boatyard mechanic recently fixed a raw-water leak originating with the water pump. It was a slow-drip leak, but the water wasn't flung around, but created rust stains on the engine. My JD is configured differently than your engine. Regardless, I sympathize.

[a64pilot]

Most likely shaft seal, and if I'm not mistaken not all that big a job to overhaul with new bearing and seals.
I'm going to guess that maybe the T is for a pencil zinc? Need to bond the zinc if that is what it's for, and that is just a guess as I do not know.
Another guess is a way to flush out the raw water side, or maybe for winterizing?

[Island Time O25]

When you say "downstream" do you mean between the raw water seacock and the pump or the pump and the engine?

If it is former the T is probably to allow the pump to double as a bilge pump in an emergency.

The leak could be from a busted seal on the pump. If so you can pretty much make a new gasket from a gasket tube sold at any of the auto stores. That would probably be be the cheapest way to address the issue, if that's the issue.

If $$ is an issue 90% of the water pump issues can and should be addressed without resorting to buying a new pump - gaskets, impeller, hoses, obstructions in the seacock, etc. 5% may require a new pump housing and the remaining 5% could be a problem with the shaft or some such.

[Folie]

Wow-- you guys responded before I even got thru editing my first version! Thanks a lot!!

[Folie]

To a64pilot----
I believe it is NOT for a zinc. I asked EVERYONE (dealers, Yanmare Cust Service, more) if this engine had any zincs-- EVERYONE ---and I was told no.


This is when I first acquired Folie.


Geeze--- if you guys have a Yanmar 3YM20. 20HP. and you disagree then let me know please.

[Folie]

To InlandtimeO25--

I thought of the emergency bilge pump thing too but it is like this----



EngineSeaCock>>>>RawWaterPump>>>>"T">>>>>>Intodept hsofEngineThatISToHeatExchanger.

[Folie]

The video is now functional-- if you can stomache the 15 second!!! adversisement!


YOu cant see much any how.

[Island Time O25]

Originally Posted by Folie

To InlandtimeO25--

I thought of the emergency bilge pump thing too but it is like this----



EngineSeaCock>>>>RawWaterPump>>>>"T">>>>>>Intodept hsofEngineThatISToHeatExchanger.

Then, like was said, perhaps it's a winterizing drain..

As to zincs I would be very surprised if this particular model does not have any. I'll ask a friend who is a marine diesel mechanic for the past 40+ years.

[sailorchic34]

I'm with A64pilot. It's probably the water seal in the raw water pump leaking. Only leaks with the engine running, at least at first.

There is a slot under the raw water pump that lets the water that leaks past the seal to drip out and not destroy the bearings. What happens is the drip falls on the hose and runs to the low point and then drips. Really hard to see when the engine is running.

Easy to replace with a pair of snap ring pliers.

Remove raw water pump.
Remove back impeller.
Remove pulley then remove snap ring.
Then pull the bearing shaft assembly out. Might have to Gently tap it out from behind. Use a Brass drift

You will find that there is a mineral buildup around the water seal and shaft. The water seal then can be tapped out.

The shaft might be scored but that's not a big deal for the first go round. So sand the shaft clean where the water seal. Sometimes that's all you need to do. But since it's apart go and replace the seal and bearings too if there is slop in them.

Take the bearings and water seal to a local bearing supply house. They should be able to give you matching ones as they are very common size. Get two water seals to have one for spare.

[a64pilot]

My 4 JHE does not have any zincs either, having said that, if you take apart the heat exchanger, I'm pretty sure the entire "sleeve" around the tubes is zinc, at least if you put it in muratic acid, it acts like zinc, so don't

I surveyed a Hunter 356 before I bought my current boat, what was interesting on it was the owner had installed a T in the raw water hose and had a pencil zinc in the T. He was an EE so he knew enough to ground the T to the engine block.
Those were all guesses, but I think drain for cold weather makes the most sense, if it's in the lowest point.

All I'd add to SC's post is if the shaft is scored, chuck it in a drill and with 400 wet or dry sandpaper spin it with a drill to polish out the scoring.

[jimbunyard]

If it's unrepairable as described above, it is a Johnson pump model F4B903, p/n is probably 10-13492-01 and there is one, complete with mounting bracket, on Ebay here for 275.00.


Yanmar Raw Water Pump | eBay

[Folie]

To SailerChic34--- Thanks for all the great detail!


I'll let you know when I am done-- Rick


Thanks to everyone.

[Folie]

ByTheWay---


Up here in Anchorage we suck pink antifreeze into the raw water system.


Half gallon does it--- start the engine---remove the top of the strainer, stick a LONG neck funnel into the strainer, close the seacock while pouring pink antifreeze into funnel, quickly kill the engine.


We used to wait till pink antifreeze was blown out with exhaust but now we know 1/2 gallon is the right amount so is now a solo job.

[svstrider]

Originally Posted by a64pilot

Most likely shaft seal, and if I'm not mistaken not all that big a job to overhaul with new bearing and seals.
I'm going to guess that maybe the T is for a pencil zinc? Need to bond the zinc if that is what it's for, and that is just a guess as I do not know.
Another guess is a way to flush out the raw water side, or maybe for winterizing?

+1 for shaft seal for cause of drip PLUS water flusher for T piece's use. If you have not YET got down & dirty with the water pump on your engine, you are one lucky sailor. REMEMBER "engine maintenance in exotic locations"


I gave up using liquid gasket goo as ALWAYS I either used too much and red goo ended up in the thermostat &/or in the exhaust elbow OR I did not use enough and the bloody pump face leaked when I put it back on. I now buy the expensive gasket from Yanmar. Reinstallation of the water pump on my engines involves lying on top of said engine and, totally by feel, reattaching the two retaining bolts, doing up the water line clamps and tightening the belt. There is a bloody bulkhead just in front of my engines

Get new seals & bearings done and ask to watch the process because, trust me, when your water pump fails in the middle of nowhere, you need to be able to do the job yourself

Below is a link to a site that shows the process of bearing & seal replacement. Pics are good.
https://coxengineering.sharepoint.co...Waterpump.aspx

Site has other good stuff. Worth downloading.
Have fun getting down & dirty with your water pump.