Stuck Anode

pluffmud

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Hi everyone. I have a Volvo TAMD31B in my 28’ Ellis. There is a zinc anode in the end cap of the heat exchanger that looked to have some corrosion built up on the outside. I’m not sure the last time it was changed. I hit it with some PB blaster and the plug unscrewed easily. It’s in good condition however I couldn’t put the new anode in because it appears the old one may be corroded in place. Has this happened to anyone else? What sort of work am I looking at to get this back to normal?

Thanks!
 

plowin

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Not familiar with that model Volvo but typically that bronze plug that you removed receives the pencil inc into the end of it and it is then screwed back into the heat exchanger or whatever it is that you are trying to protect.
 

ARC

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You may have unscrued the plug and pulled the old swollen zinc into the threads. In this case it is best to pull the cap off clean everything out , chase the threads , inspect and reassemble with new gasket.
 

GH37

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ArchHibb

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If you can see the zinc and it’s stuck in the HX cap fitting, just take a drywall screw (or other type with a wicked sharp point) and try gently screwing it partially into the zinc. The zinc will be soft as evidenced by it parting with the brass plug, so no need to drill anything. Often you can get a grip and pull it out.

Just as often, the zinc will break loose and fall inside the HX cap. In that case, plan on doing a system flush with Rydlyme or sim. which will dissolve the zinc in addition to any marine growth.

Otherwise, the other solution is to pull the HX cap which means draining your coolant system.
 

ARC

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Otherwise, the other solution is to pull the HX cap which means draining your coolant system

I’m not that familiar with that engine , but most Zincs are on the seawater side .
 

ArchHibb

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Yes, but all HX’s contain both sea water and coolant. Only some permit pulling the cap(s) and not disturbing both circuits.
 

TCL

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In the past I have removed a hose and used forceps to remove a zinc that went all the way into the cooler.

You can also take the brass end piece and grind off all the treads plus a little bit more, then tread it back onto the zinc and grab with gripper pliers and wiggle it out.
 

speedwagon

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I had the same thing happen with both anodes and ended up replacing the plugs rather than struggle cleaning the threads. The one I put in the oil cooler was purchased from boatzincs. Here's the link to the page.https://www.boatzincs.com/volvo_engine.html
 

TCL

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Once you get the zinc out you can take a pencil and wrap it with some sand paper to clean the hole, but be careful not to damage the threads that hold the brass piece in place.
 

pluffmud

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Thanks for all the recommendations. The threads on the plug and cap of heat exchanger look to be in good shape. I want to try and extract the zinc but worried some might fall in. Would this cause any damage? It would be isolated to the seawater side. My guess is it could cause a little blockage in the HX but I would think it would eventually dissolve. FWIW it's a double pass HX.
 
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Thanks for all the recommendations. The threads on the plug and cap of heat exchanger look to be in good shape. I want to try and extract the zinc but worried some might fall in. Would this cause any damage? It would be isolated to the seawater side. My guess is it could cause a little blockage in the HX but I would think it would eventually dissolve. FWIW it's a double pass HX.
I like TCL's idea of grinding the cap plug and using it as a puller. Most end caps, like SenDure, only hold back the sea water, the tube bundle holds the coolant. If the end with the zinc has a sea water hose just push the zinc in, pull the hose and take the zinc out.
I don't like leaving the loose zincs in there as some cooler bundles (like Cummins B/C aftercoolers) have the tubes protrude past the support plate a little bit and a loose zinc bouncing around in the sea water flow peens the tube ends shut. Check new zincs to their caps, they are are almost always loose.
 
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pluffmud

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Old Zinc out new Zinc in! I tried using a screw as suggested but the old zinc quickly started to fall apart. The big chunk I was able to get with some tweezers and left some little debris in there to dissolve. The threads on the plug and the HX cap were in good shape so I cleaned up the opening a little and the new Zinc fit right in. Took her for a little spin and everything is running smooth. Very glad to have this behind me and happy it didn't turn into a bigger ordeal. Really appreciate all of the suggestions and help. Thanks everyone!
 

traditions

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I have taken a zinc plug, and machined the threads off, and made a puller out of it. I have had a couple engines that have been problamatic with this problem. When you unscrew the plug, and the zinc remains in the engine, I screw the machined plug onto the threads on the zinc, and then use vice grips to twist and remove it. I have a lathe, but you could rough one out with a grinder.Just remove the threads so you can screw it all the way in on the zinc threads
 

TCL

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I have taken a zinc plug, and machined the threads off, and made a puller out of it. I have had a couple engines that have been problamatic with this problem. When you unscrew the plug, and the zinc remains in the engine, I screw the machined plug onto the threads on the zinc, and then use vice grips to twist and remove it. I have a lathe, but you could rough one out with a grinder.Just remove the threads so you can screw it all the way in on the zinc threads
Yes, that’s what I did.

Also, I assemble my Zincs with LockTite so that the zinc stays attached to the brass plug.
 
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