Unfreezing the Zinc Anode Plugs

[Captndave1]

All you have to do is grind a flat on each side of what is left of the nut, then instead of heat, place a piece of dry ice on the nut, this will cause the nut and the cast block to shrink thereby releasing the threads.
easy peasey

[RaymondR]

By applying sufficient torque to round of the hex in the plug you have demonstrated that it is unlikely that any of the EzyOut type solutions is likely to work and with the likelehood of breaking off an un-drillable material in the body of the plug which will obstruct further attempts.

My next attempt would be to weld a steel rod onto the head of the plug and use a pipe wrench on the rod to apply undoing torque.

If that failed I would cut off the rod and drill a row of holes across a diameter of the plug, being careful not to damage the threads in the engine block, and break the plug into segments I could tap away from the threaded hole and remove the pieces.

[Wotname]

Originally Posted by pateco

After reading this I decided to not use heat for mine. I have this same issue, but a six point socket even with a breaker bar would not move it so I went to an air impact wrench, and instantly destroyed the plug. what are my options now? I am now considering a bolt extractor socket and heat.

Originally Posted by Suijin

I suspect that the extractor is not going to work any better than the impact wrench did, but it's not going to make matters any worse than they are at this point. You may in the end need to drill it out and tap it for a helicoil to repair it. Not sure if helicoils are used in marine work but they are for automotive.

I've heard a lot of horror stories about impact wrenches on seized engine bolts to the point that I think it's A Bad Idea unless you're certain the bolt is simply tight and no corrosion is in play..

Originally Posted by RaymondR

By applying sufficient torque to round of the hex in the plug you have demonstrated that it is unlikely that any of the EzyOut type solutions is likely to work and with the likelehood of breaking off an un-drillable material in the body of the plug which will obstruct further attempts.

My next attempt would be to weld a steel rod onto the head of the plug and use a pipe wrench on the rod to apply undoing torque.

If that failed I would cut off the rod and drill a row of holes across a diameter of the plug, being careful not to damage the threads in the engine block, and break the plug into segments I could tap away from the threaded hole and remove the pieces.

I have to concur that using an air impact wrench is sometimes not a good idea. I know some folk swear by them but as others have suggested, sometimes you have to swear at them. I also concur that a bolt extractor is unlikely to work at this point.

I have had a couple of frozen anode plugs on Yanmar GM engines but have always (so far) managed to free them using a good six point socket (24mm), a breaker bar and a extension pipe. The worst one needed a 6 foot extension bit of pipe on the breaker bar and a shipload of force but it came free - I hate to think what sort of torque was being applied . This is case where a steady large (very large) force is better than an sudden impact - IMO.

But this is no help to Pateco at this stage. I don't wish to alarmist but I think you might have to pull the engine to get this plug out. It appears you don't have great access and I suspect you may have to resort to RaymondR's welding suggestion as the next step. However much work it is to pull the engine, this may be better in the long run. Besides it could do with a close inspection after all these years.

I'm betting the anodes have been long shot; they only last a couple of years IME before they need replacing and really, they should be inspected every year. Also the block and head should have flushed every few years (3 to 5, IMO) with either a 24 hour vinegar (or a hour of Muriatic acid) flush to keep the salt build up at bay. Note the thermostat and anodes must be removed for a successful flush.

Good luck with getting it out, please let us know how you finally achieve it.

[hugosalt]

Have had same situation years ago on my 3 GM raw water motor. After not changing engine zincs for maybe 10+? years. (my fault, did not know they existed)
(have not read thru thread)

I am not shy about these things but after much time and effort trying to muscle loose with all the usual tricks and very long extension bar, and afraid i would destroy motor with my brute force, i decided to bring to my Yanmar parts/mech service ...who put 2 mechanics? on it and they proceeded to do exactly want I was doing... only more brute force and a even longer bar. I could not look on. 10 minutes later we were changing out zincs which were still very much intact.
Grind edges to your head and use dry ice on head will help break free.

[jimbunyard]

Took one look at this picture



and thought 'pipe wrench'.

But of course, there's not much room...

Never underestimate the power of the internet; if you can imagine it, someone else probably has before you...

First image under a search for 'socket drive pipe wrench'




New Pipe Wrench Head Offers Greater Flexibility | Lowell CorporationLowell Corporation

Unfortunately it's very pricey, 309.00, and only closes down to 1 1/2". Don't know if they or anyone else makes a smaller or cheaper one.

For a more realistic option



https://www.amazon.com/IRWIN-BOLT-GR.../dp/B000QW6K8I



which grip the outside of a rounded off head, are much more reasonably priced, and work pretty good. The advantage is that most anode plugs are tapered; once broken loose, they usually come the rest of the way fairly easily. Try these with the dry ice trick and you might have success...


Or, if you're reasonable patient and proficient, center punch the plug head, get an extra long, regular twist 1/4" drill bit and drill a fairly deep pilot hole, followed by step drilling with increasingly large left hand drills (and an extension if needed)





https://www.ebay.com/itm/15pc-Left-H...4383.l4275.c10

until the damn thing gives up in frustration, or the stress relief from removing most on the metal from the interior of the plug loosens it, or you can get a big enough screw extractor in, or only the threads are left and you get to pick their remains out (followed by a chase with a pipe tap...)

[Dymaxion]

Can try a wire brush the surface around the plug until free of crud. Then soak it 24hrs in Kroil or PBBlaster or Moovit or similar top quality penetrant. Throw out the WD40 can if you have it. Propane torch for heating it up well, blast again with penetrant, and try a pipe wrench with extension pipe on handle. Rap the end of the plug smartly inwards at same time. The combo torque/axial forces often works where torque alone doesn't. Once you start drilling/grinding etc it's a slippery slope ending in no metal to grip onto. Good luck, not a pleasant task. And you thought the job was just going to take 20 minutes... ��