question regarding zincs

[magna 6882]

Hello all
First time with the zincs. I have been watching one that was on top and easy to get at(number two in the picture) and it seemed to be looking ok so i assumed the others were wearing at the same rate. Its at a year so i decided to replace them all. The first one is at the fresh water to the aftercooler the send is at the back end of after cooler on top the 3rd and 4th are from the exhaust. Do you think the first totally dissolved or is there a piece of zinc still inside and if so is that going to be a problem or will it dissolve ? Also do some zincs wear at different rates? looks like a year is to long.

 

[Comodave]

Hello all
First time with the zincs. I have been watching one that was on top and easy to get at(number two in the picture) and it seemed to be looking ok so i assumed the others were wearing at the same rate. Its at a year so i decided to replace them all. The first one is at the fresh water to the aftercooler the send is at the back end of after cooler on top the 3rd and 4th are from the exhaust. Do you think the first totally dissolved or is there a piece of zinc still inside and if so is that going to be a problem or will it dissolve ? Also do some zincs wear at different rates? looks like a year is to long.

No photos. The anodes should be replaced when they are about 50% gone. Depending on where your boat is located they will either be zinc, aluminum or magnesium. Zinc for salt water, magnesium for freshwater and aluminum is good anywhere. If the anode doesn’t come out with the plug then you should take the cap off the heat exchanger and get the rest out. Yes, they may wear away at different rates.

 

[magna 6882]

Sorry. i forgot to add the photo.

 

[Comodave]

It looks like there is probably a piece of the anode in the exchanger. I would open it up and check.

 

[Bacchus]

Inspection scopes are inexpensive and might provide enough of a view to determine if there is a broken anode inside. If disassembly is difficult it could ease the work. If removing cap is easy & accessible disassembly provides a better inspection... choices!
Most often it breaks trying to remove it and the break is evident on the plug that is removed. Yours looks more worn than a break.
The Performance Metals anodes have a steel reinforcing wire in the center that minimizes breakage and I have switched all of mine over and like their anodes.
https://performancemetals.com/

 

[DavidM]

Different zincs on the same engine waste at different rates, probably due to some areas draining after shutdown and others staying full. Monitor them and figure out which are the worst and replace them all based on that one's life.

David

 

[Bkay]

The Performance Metals anodes have a steel reinforcing wire in the center that minimizes breakage and I have switched all of mine over and like their anodes.
https://performancemetals.com/

I've not seen aluminum engine anodes. Thanks for that source!

 

[Bacchus]

I've not seen aluminum engine anodes. Thanks for that source!

Yes... they have a very complete assortment and I had problems finding all the alum I needed. They sell thru distributors and many dont carry a full assortment. When I called them to inquire they checked my area and said no local distributor and OK to order direct from them.

 

[Comodave]

I couldn’t find aluminum anodes for our heat exchangers so I had to use magnesium ones.

 

[magna 6882]

I went down today and pulled the one from the hydraulic heat exchanger and it was gone entirely. I did open that unit and there was nothing in there. No metal rod on this one. I think this may be the worst so i will watch this one. It is dumb luck that the one i have been watching every couple of moths was the one that was in the best shape.

 

[porman]

On my Yanmar engines the anode in the oil cooler wears out twice as fast as the others. I've read that is normal in these engines.

 

[magna 6882]

Here is a picture of the oil cooler.I had to open it up to verify any anode had broke off. Nothing in there.

 

[magna 6882]

Do you guys think i should use some barnical buster to clean this up? Is this caused by the bad zinc maintenance or is it just salt water? Not sure if this should be a new thread.
Rod

 

[Bacchus]

Rod
Zincs/ anodes prevent metal attack by reacting preferentially to the metals you don't want to be attacked by galvanic corrosion. If not maintained you can get galvanic corrosion.
What you have looks like mineral build up and just the nature of operating in salt water or hard fresh water.
Actually that looks like a transmission cooler due to small size. Engine oil coolers are much larger with MANY small tunes inside a 6"-10" dia shell.

 

[Comodave]

Do you guys think i should use some barnical buster to clean this up? Is this caused by the bad zinc maintenance or is it just salt water? Not sure if this should be a new thread.
Rod

When we brought our last boat home to fresh water from salt water I used BB to clean out the exchangers. One engine dropped 10 degrees and the other dropped 5 degrees. Not a bad return for a small investment. We just sucked in the BB and let it sit for the prescribed time and then started the engines to flush it out.

 

[firehoser75]

Magma,
You can improve overall engine life with a simple procedure. Freshwater flushing the raw water side as often as possible! This simple and inexpensive procedure will slow down the ravages of exposure to salt water reducing "marine aging" of your engine. Your engine ages even just sitting unused when it is full of saltwater.

This will not eliminate the need for full "off engine" servicing of the raw water components (especially the aftercooler, if equipped), but it will allow you to extend the time interval between this servicing. The aftercooler requires complete PROPER servicing even more often than the rest of the cooling system. See sbmar.com under "Tony's Tips" for details. An easy way to FW flush is to install (or adapt) a garden hose bib on the lid of the sea strainer. If you do decide to FW flush, switch to aluminum anodes in your engine. FW flushing takes me less than 10 minutes to take out the hose, flush, and put it away again, so it is not a big deal in terms of time or cost, but it is a big deal in terms of "saving your engine's" raw water components and keeping your engine running at the proper temperatures.

 

[silverback]

I see in your photo the actual version of a plan i had been thinking of. Great, how do you regulate the choose the flow from the tap? I have another question.
Is there a tool to unscrew the top of the strainer. I have been dropping the bowl to clean it but live in fear of a leak every time i do so.

 

[firehoser75]

Tool to easily remove lid to the sea strainer. https://www.groco.net/products/raw-water-strainers/accessories/spanner-wrench
To safely freshwater flush the engine with the dock hose attached to the fitting in the photo:
Attach the "garden hose" to both the dock fitting and the sea strainer. Leave the through hull open. Turn on the dock water (full on). By having the thru hull open, the pressurized water just exits the bottom of the boat while actually backflushing the thru hull. Start the engine, and close the thru hull allowing only freshwater to cool the engine (engine in neutral at idle). Run for 5 minutes. If 2 people are available, shut down the dock water supply (can be at the sea strainer fitting) at the same time as the engine is shut off. If only one person is available, shut off the dockwater, then quickly shut down the engine (as soon as possible - seconds). You can flush with the seacock anywhere from fully open to fully closed. You will still receive benefit from flushing with freshwater. You do not want to have pressurized water going into the raw water pump with the engine off!!

 

[silverback]

Thank you. Very simple. I imagine zinc anodes would need changing to aluminium?

 

[firehoser75]

Silverback,
Yes, that would be a good idea. By the way, I loved Airlie Beach when we were visiting there in 2009. Too bad we got "chased out" by "Hamish".

 

[silverback]

Yes the Whitsundays area is a marvellous cruising ground. Mostly being national parks.
Cyclones in the lats 10/15 years have resulted in insurance premiums triple. Bastards.

 

[C lectric]

As said the zincs will NOT all be eaten at the same rate.
YOU must examine them frequently enough to determine the wastage rate and replace at about the 50% gone point. Then use that knowledge to determine the replacement intervals. There will very likely be one of two that must be changed on a much more frequent interval than others.

You must determine their, the anodes, schedule regardless
of the material used for anodes. Just deciding to check on your schedule is not enough and will cause trouble as you are discovering.

I use a wrench/vise and pliers to snug the anode into the cap. I dab a tiny bit of sealer on the anode threads which stops/slows the threaded part of the anode wasting and thus the falling off of the anode.

I also use a small amount of sealer on the cap threads which stops the inevitable weeping of seawater through the threads. Snugging up the caps will make electrical contact even through the sealer as the metals make contact. Check with a meter if you don't believe.

The sealer I use is Rectorseal #5 but there are other good ones, non hardening types which will seal but not glue.

 

[Marco Flamingo]

This wasn't the OP's problem since he opened the heat exchanger and found nothing, but I had a weird experience where I pulled the brass plug and found nothing. Put it back in and went to the chandlery. Came back and pulled it and there was an old zinc in fairly good condition. It was like a magic trick. Apparently it had unscrewed itself the first time and then screwed back on the second. I was (and still am) confounded. Had to think "senior moment?"

As to fresh water rinsing, isn't there the possibility of overfilling a water lift exhaust and having water enter the exhaust manifold? I've heard of cranking a non-starting engine too long and over filling the water lift. I don't see quite how it would happen with my engine as the exhaust loops up about 12 inches higher than the transom outfall. But if the problem is possible with a raw water pump operating without exhaust to blow out the water lift, why not fresh water injection without exhaust?