Where are the engine zinc anodes located?

[rlathers]

Have had my Hatteras for almost a year and now realize that I need to be checking and possibility replacing my engine zinc anodes.

Where are they located on a Detroit Diesel 8V92Tib and what model zinc anodes are they??

Thanks for your help.

Rob Lathers
1990 54ED Hatteras

 

[Bob Bradley]

Probably the same place as my 6v92s had. 2 in each heat exchanger and 1 in each raw water pump. I eliminated the one in the raw water pump and replaced it with a fitting to simplify winterizing the motors. Not sure of the zinc model.

 

[oscarvan]

On my 8V71TI Two on front bottom of the heat exchanger. (The reservoir with coolant in it.) Two brass solid caps. From memory 1"...... Probably slightly more or less...... And one in each raw water pump. One is a PITA to get in or out and has to be ground down a little.

 

[rlathers]

Thank you!!

 

[Captain Ralph]

I think 3/4" NPT (x2) on the larger cast DD H/E, 1/2" NPT (x1) on the raw pump.

 

[Blowncar]

You should have 1 in each of your fuel coolers as well.

 

[cww]

They're the big bolt heads on the flanges on either side of the heat exchanger. If you take them out with a socket, a standard detroit zinc pencil screws onto the other side of it and then you just stick it back in. Easy peasy. After you do it the first time it's a 2-minute task.

 

[Captain Ralph]

You should have 1 in each of your fuel coolers as well.

TI fuel coolers no, TAs yes. Good catch.

 

[cww]

You should have 1 in each of your fuel coolers as well.

My 8v71ti's don't have fuel cooler zincs (I think they should, I've replaced multiple fuel coolers for pinholes over the years), as far as I can tell just the two by the heat exchanger. Are there some I'm missing?

 

[Captain Ralph]

My 8v71ti's don't have fuel cooler zincs (I think they should, I've replaced multiple fuel coolers for pinholes over the years), as far as I can tell just the two by the heat exchanger. Are there some I'm missing?

Zinc on the engine side of the raw water pump. Rite on the elbow that bolts down on the pump.

 

[Play'N Hooky Too]

They're the big bolt heads on the flanges on either side of the heat exchanger. If you take them out with a socket, a standard detroit zinc pencil screws onto the other side of it and then you just stick it back in. Easy peasy. After you do it the first time it's a 2-minute task.

Maybe I'm using the wrong size pencil zincs or not changing them out frequently enough. About half the time the zincs, or what's left of them, have swollen to the point that they won't turn out with the brass plug. I unscrew the plug and then I'm looking at the threads on the zinc which is now stuck fast in the opening. I'm still going through the bag of pencil zincs that was left by the PO which I presumed were for the engines since they seemed to fit. They are about 1/2" diameter by about 2-1/2" long.

 

[Captain Ralph]

Maybe I'm using the wrong size pencil zincs or not changing them out frequently enough. About half the time the zincs, or what's left of them, have swollen to the point that they won't turn out with the brass plug. I unscrew the plug and then I'm looking at the threads on the zinc which is now stuck fast in the opening. I'm still going through the bag of pencil zincs that was left by the PO which I presumed were for the engines since they seemed to fit. They are about 1/2" diameter by about 2-1/2" long.

Yes, correct zincs.
There is a fine line in tightening the zinc into the brass plug.
Tighten just before it breaks off.

Then you are checking them to late or to early;
To late, they have gotten soft to the thread.
To early, they have not dissolved away yet.

I try to use a stiff set needle nose pliers and gently rock and pull the old zinc out when I find my zinc still in the hole. 50/50 results here for me. When it does come out, not much is left past that last little end in your hands.
Once loose or if it falls in, they will continue to turn to zinc mud and settle to the bottom. IMO, the zinc mud blows out.
About 15 years ago, I got upset about this and tore my big HE apart for the first time. No zincs or mud. Not worried about it since.

 

[Play'N Hooky Too]

I was worried that they might clog up the H/E core, but like you said, whenever I've taken them apart to clean the cores I didn't find any evidence of old zincs inside.