Zinc pencil location?

[garyd]

Reading my engine operators manual it referred to a zinc in the raw water pump elbow. I believe this is where you prime it. When I recently took mine out it was not a zinc pencil.

Does anyone know if there is or is not supposed to be one in there?

thanks and have fun boating garyd

[captbuddy]

My mechanic told me to keep mine out of there. He stated when it starts to deteriate it is subject to damage the vanes in the impeller. I have one on each side of the heat exchanger. Seems to be OK.
captbuddy

[Paul45c]

I think CaptBuddy's right...they are ported for a zinc, but it's not recommended to put one in there for the reasons he gave.

[Nonchalant1]

Very interesting question I have zincs there and on the HE intakes and output sides, but a year ago I found some ancient pieces of old zincs from the raw water pump stuck in the intercooler raw water intake vanes, which is the first place the water goes on and 8V71TI. I'd like to remove them from the pump and just rely on the HE zincs.

Doug Shuman

[Boatsb]

Mine had the ones in the pump removed by the PO and I had a mess. I had one pump and housing damaged and had to send it to Depoco ( great company). The other was not as bad but both engines show problems from lack of maintenance. I chose to put new ones in and change them every 6 months so I do not loose pieces. Seems to be working and I am repairing the corrosion from the PO's lack of attention.

[Nick]

My mechanic suggested not putting in the zinc on the intake elbow to the raw water pump just as Captbuddy and Paul noted above. I have a zinc in an elbow on the discharge side of the pump, two in the gear cooler, one each in fuel cooler, intercooler and the heat exchanger in 671TIs. I seem to eat up the zinc in the heat exchanger in a couple of months.

[Dodger]

This is why you don't want zincs upstream of critical items such as water pump impellers. This was his intercooler "in" port. Not something you want to use as an in-line strainer.

[garyd]

Wow the other interesting thing about that picture is the threads of the zincs. He must have thought they were being used up. But in fact they were coming loose and falling off.

Note to self make sure the zincs are tightened down before insertion.

It may be if they are properly torqued down and then located in the correct locations the system works.

Have fun boating garyd

[Captned]

Where does the zinc go in the fuel cooler? I'm having a lot of trouble with my fuel coolors not being protected and starting to turn pink. Can I bond them to the rest of the engine? Any suggestions?

Thanks, Captned.

[REBrueckner]

Interesting discussion; Great photo!!!

This is a subject in which I'm really interested. Separately, I posted that my stb engine is running a bit warm...I've checked everything except the intercooler passages and thermostats. I suspect zinc pieces from the raw water pump may be blocking the intercoolers a bit. I'm going to disassemble them in January and see what's inside and have them cleaned. Last step would be thermostat replacement. I think I forgot to check the pump zincs last winter...or forgot to write it in the mtc log!!!

On my 8V71TI's, the salt water at the raw water pump seems to be there full time. When I remove the zinc plug, I can hear water gurgling down sometimes a bit may dribble out. But when I check the heat exchanger zincs, there never appears to be any water present. True, it could drain at a point where I can't hear it, but it seems like they are in the water only when the engine is running. (Yet I don't know how it can drain unless its some sort of syphon effect. The pump at one end and shower head at the exhaust end are higher than the zincs location.) Engine zincs deterioriate more from vibration and water abrasion than from protection...something like shaft zincs.

For anyone with evident corrosion, it would be a good idea to check for stray currents from either shoreline power if you are plugged in much of the time,without an isolation transformer, or a some onboard leakage. In general, there shouldn't be much corrosion within an engine because the salt water piping restricts current flow. In other words, the small cross sectional area of pipe introduces a relatively high resistance. Since most Detroit salt water components are corrosion resistant (stainless shafts, bronze housings,rubber hose connections, etc) there should not normally be much galvanic corrosion (caused by metals of different potential). But the zincs should help prevent stray current corrosion when submerged.