Removing old Pencil Zinc from Cap

[sgharford]

Does anyone know any nifty tricks for removing old pencil zincs from their bronze caps? The two from my transmission oil coolers are gone right down to top of cap (just the threaded zinc portion left). The ones on engine heat exchanger are half gone, but got some meat to get pliers on.

 

[MikeP]

You can drill out the zinc from the cap once you break off all the zinc after trying the pliers thing. I did this once but frankly, the effort is not worth the time and I would just buy a new zinc/cap and change the zincs more frequently so that they are not so disintegrated when you change them the next time.

 

[bobk]

Punch a centering dent on the stub and drill as large a hole as you think will not ruin the plug's threads, then put the plug into some warm acid, vinegar works well. When the bubbles stop, it is ready to use again.

Bob

 

[REBrueckner]

I bought my last zincs/caps in a package of six so I'm not up to date on prices...but as I recall the zinc plus cap costs about $1 more than a zinc alone...so it they don't clear easily, I just buy both...I'm cheap, but there are limits....

 

[Captned]

Muratic acid? I think I have done that before....

Cheers!

Captned

 

[Passages]

Muratic acid? I think I have done that before....

Cheers!

Captned

Naww, tried to recover some caps using full strength muratic couple years ago. Let sit overnight and still had much zinc imbedded in the cap.

I agree with others, it's not worth the effort.

 

[sgharford]

Figured it was worth asking. I have muratic acid at home so I'll give it a whirl and see what happens. The transmission h.e.'s really appear to take a beating. I replaced these last year as orginals were rotting away. Guess a high flow of water thru them so will have to pay them a visit more often. Thanks guys!

 

[sgharford]

So I used muratic acid last night and it worked too well. It took a couple of hours on one cap to dissolve zinc but it worked. However, I think it may have also degraded brass caps. One of the caps came out white (then turned copper color). They feel lighter than they should after their acid bath. I think the acid ate the zinc out of the brass too (Brass is copper and zinc, right). I’m going to throw away the brass caps and just use new ones. Like Chemistry Lab 101 all over again – if I only had a Bunsen burner on my work bench.

 

[Captned]

Funny stuff. Not to hijack the thread, but I just removed my water pump because it was leaking slightly and was finally able to remove the zinc (for some reason I could not get it out while it was on the engine) Needless to say it was shot. I drilled the old piece out with one of those easy out removers, got most of it, dropped it in Muratic for about 30 seconds and voila! Clean as a whistle. I did have to run a SS bolt in and out of the fitting a couple of times to completly clear out the threads. Shot of paint on the cap, looking good! Side note, Detroit Diesel wanted $780 for a rebuild kit for the pump. YIKES! Got a small rebuild kit from Depco for $118.

Cheers!

Captned

 

[MikeP]

You might consider leaving the zinc out of the pump. It just gets badly and quickly eaten by the water pressure in that location. Per the PO, our 53 has not had a zinc there at least since he bought the boat in 1990 or thereabouts. It still has the original waterpumps so it seems pretty safe to suggest there is no need for a zinc in the pump and it just creates debris to clog the intercoolers and/or heat exchanger. Frankly, the same is true of the first zinc in the HE.

When I pulled the HE to clean it, most of the debris in it was zinc. THe second zinc in the HE would not cause a problem because its debris is washed straight out into the exhaust.

In our 53MY, with 8V71TIs, the water level in the HE is below the zincs when the engines are not running so they do absolutely nothing anyway as far as protection.

 

[Captned]

Hey Mike,

I am thinking about that, but, what the hell, maybe I'll give it a shot for awhile and see how fast it corrodes. I only use the boat about 50 hours a year....

Cheers!

Captned

 

[Traveler 45C]

Dropping the caps in some Ospho will also take out the zincs. Much better stuff to work with....No fumes!

 

[mobilemn1]

dremmel tool and flatten surface, center punch the center for bit starting, and use a left hand drill bit that turn opposite what we normally think of (bit cuts turning counterclockwise rather than clockwise) , and as it is drilling down, most times it will loosen the threads and screw comes out with the drill bit before drilling all the way thru. If not pic out with an awl. Or just run a clean up tap thru. And your'e done.