Yanmar raw water blocked! Help-semi urgent

[Wotname]

Originally Posted by tdh1849

Get the tel# for "Complete Yacht Service" in Ft.Lauderdale, ask for Mark, the owner ( USMC) tell him Pat N, formerly from there now in Tampa told U to call.
He is the Yanmar dealer there and knows everything there is to know about Yanmars.

And don't forget to tell him that you are calling from Australia

[iWeb]

Ok, so far, goodish.
Slip job pretty much done.
Took jacket off, very heavily fouled, no surprise there. Couldn't blow through the channel to the elbow. There's one blockage.
Scraped it out and gave jacket a clean out, much clearer now.
With the jacket still off, took anodes out, pumped water through block, plenty of flow, although lots of calcium bits in there, scraped out what I could get to.
Refit jacket on old gaskets temporarily, to check water reaching elbow, pumped, no flow. Remove cover on siphon, and hear it faintly click. Clean siphon, no debris, refit.
Pump again and hey presto, lots of water spouting out of elbow!
So maybe siphon jammed too?
Refit stat, impeller and raw water strainer.
So I'm thinking it might be ok to get me to my mooring, gaskets will leak and poss fumes in cabin, so will sail but use engine when necessary.
What do you think? Sound reasonable?
I will of course, when on mooring start a proper overhaul of the cooling system and from now on flush it every year!
Thanks got your assistance, I read frequently, post occasionally but have always found the cruisers forum an invaluable resource.
Cheers webby


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[Rick Williams]

Had the same problem on a much smaller Yanmar. Could not find an obvious problem so I just started replacing/rebuilding everything from intake out.
Turned out to be a 1" long fish was stuck in the elbow of the intake to the strainer. Must have grown up from an egg.
Worked great for some time then it would overheat only when I revved above 2400 (like when you're going through a bridge..). Same process, found a small mussel in the outflow of the strainer that would allow flow but not enough at high demand. I found it because I was carefully examining and removing/replacing everything.
The good news is that's all finite; there's nothing to be invented, just understood and fixed.
R

[kenL]

I had the exact thing happen on my raw water Yanmar 20 hp model ? and found that the exhaust elbow was completely blocked with salt. I replaced it and now I put Salt- Away in the engine after about every other trip out and during any long periods of no use. They make a hose style injector much like one might use to apply liquid fertilizer that I hook up to the galley faucet with inline valves and piping to feed the engine with the seacock closed. So far so good. It is supposed to leave a film that resists salt from adhering to the internal metal components along with breaking up the salt that has formed there. The stuff is expensive but a gallon will last many years. good luck.

[Woodyv12]

I have had this issue multiple times.
In our case the water strainer is quite high in the engine bay and drains out when we beach the boat.

Invaribly the water doesn't pump thru and the first couple of times we were very lost until we figured the issue.

Solution was to remover the strainer from its bracket and position it below the waterline, start motor and replace strainer in bracket when water flows

Job for holiday
Replace strainer with a proper unit that doesn't drain out and locate it with its top just above waterline.

[iWeb]

Just to wrap up this thread, all back in place, ran through an acid wash (a much simpler process than I had imagined), and engine running better than ever.
So my recommendation for all you unfortunates with raw water cooling, set up a few hoses and keep them together for an annual acid flush. I'm a convert.
Thanks for all your help
Webby


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[Wotname]

Perhaps you might care to post a shortish description of the acid wash process you used?

I for one would find that helpful.

[JRM]

I did my own acid wash two or so years ago, in place. The trick is to use Phosphoric acid, not Muriatic. It takes much longer, but is much more forgiving. They put the stuff in soda pop.

I built a wash system using a series of 5 gallon buckets, a spare small bilge pump, and some tubing. I have three heat exchangers / coolers (fresh water, oil, transmission) and flow through the tranny, so it would have been crazy to remove them all. So in place was the best option.

I spent some time in the home improvement store with my phone checking MSDS online. I finally found what I wanted at a specialty tile store. It's a generic form of grout cleaner that is dilute Phosphoric acid, but without the added detergent. I forget the brand. Way cheaper than the barnacle removal stuff sold in marine stores.

At any rate, I disconnected the raw water intake and discharge. I then hooked up my system to flow in reverse, pumping into the discharge and out the primary heat exchanger intake. I tested with fresh water, and timed how long it took to flow a gallon of fresh water through, so I could see what difference I was making. I averaged the gallon test three times. Then, in 20 minute sessions, I ran through the acid mix, which I had diluted further. At the end of each session I timed a gallon. It took a long time, but it eventually cleaned out all the salt and calcification.

When finished, I slapped a lid on the used acid mix and donated it to my work to use as a HazMat prop. It's ok to flush down a municipal sewer legally, but it made for a fun drill.

Mostly fixed my overheating issues, although the fresh water side needs some love too.

JRM

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[Wotname]

Presumably you also removed any internal zincs (if fitted).

Any idea where to get a reasonable idea of dilution of the phospheric acid?

[JRM]

Originally Posted by Wotname

Presumably you also removed any internal zincs (if fitted).

Any idea where to get a reasonable idea of dilution of the phospheric acid?

Actually I didn't pull the zincs, didn't find any increased loss. If there was any phosphoric coating, I didn't notice.

I got the acid at a stone and tile shop. It's marketed as grout cleaner. All products with hazardous properties will have an MSDS, most are available online. My local home improvement store chain carries an acceptable one at most stores (just not the one here.)

JRM

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