Finding Cummins QSB pencil anodes

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Joined
Jul 3, 2016
Messages
1,567
Location
Sandusky Bay
Vessel Name
Escape
Vessel Make
Mariner 37
Seaboard Marine has a great page on anodes for Cummins and other engines including the QSB. Mine looks about the same and I find what appear to be the same three. They all appear to be the same ½" NPT threads, but those pencil anodes come in a variety of lengths. What is the correct length?

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I watched a Seaboard video on the topic just the other day. Apparently the answer depends on the vintage of the engine.

They also said since zinc is pretty soft its easy to cut them shorter if need be. Just being careful not to crack the zinc apart in the process.

So I suppose the short answer is, consult the manual for that vintage if you have it. If not, take your best shot and cut them down if needed.
 
There is one at the bottom of the intercooler as well, 3 total. I use the 2" ones, there is a lot of space in there for them. The two you have arrows to will spill a bit of seawater but not too much, the one at the bottom will dump the better part of a gallon so be ready to catch it.
 
My 6CTAs have 3 anodes, two in the aftercooler and one in the heat exchanger. I also put the Seaboard transmission oil coolers in and they have two anodes where the factory originals didn't have any.
 
So I started with the heat exchanger anode. I thought it was an interesting pattern when it first came out, like all of the use was from the end. The top intercooler anode looked almost new. Turns out the heat exchanger anode was too; it just started out shorter. I cleaned them up and put the old ones back in.
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Pretty good bet these were zinc anodes in a boat that has been in fresh water since 2019. So is electrolysis in the engine just not a problem in fresh water, or is zinc simply not soluble enough to serve as a sacrificial anode in the low conductivity world of fresh water?
 
On a related note, I checked the soundness of the bonding system by testing the resistance between each transom anode and the rudder, but got no continuity and OL resistance. Interesting. That doesn’t jibe with the magnesium loss on the anodes. What am I missing?
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are you still in Nashville? Where did you have your work done?

So I started with the heat exchanger anode. I thought it was an interesting pattern when it first came out, like all of the use was from the end. The top intercooler anode looked almost new. Turns out the heat exchanger anode was too; it just started out shorter. I cleaned them up and put the old ones back in.
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Pretty good bet these were zinc anodes in a boat that has been in fresh water since 2019. So is electrolysis in the engine just not a problem in fresh water, or is zinc simply not soluble enough to serve as a sacrificial anode in the low conductivity world of fresh water?
If the anodes do not waste away they are not working. You want them to wasre away so other much more expensive metals do not waste away. Yes zinc anodes do get a coating in fresh water that prevents them from working. So if the anode isn’t wasting away something else is. Yes in fresh water you do get wasting away of metal but not as severe as in salt water. If the boat is going to stay in fresh water change to either aluminum or magnesium anodes. I use magnesium in the engine and aluminum on the hull. That is ok because the engine is considered a different body of water.
 
Yes, you want aluminum anodes for the Great Lakes. I tend to buy the longest ones and cut them down to fit.

Ted
 
Boatzincs.com has prepackaged sets for all Cummins engines. Price is good and delivery fast. One call telling them which engine and done. Usually 4 long ones and 2 shorter. Holders are different.
If you want to save a few pennies you can just buy the zincs and reuse the holders. I don’t bother with that as I don’t want to spend the time to remove the old ones.
Might want to check with SB as to which material for the anodes. I used zincs generically above.
 
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