Removing Zinc Anode Plugs from Engine

casey1999 · #1 (**permalink**) 02-07-2011

Would a impact driver be ok to use to try to remove a Zinc anode plug from an engine block. With an impact driver and can apply a force onto the plug which I cannot do with a socket and breaker bar. The breaker bar method rounds the head of the plug. But will the impact driver potentially break the engine block? Trying to remove some rusted in zinc anode plugs.

MARC2012 · #2 (**permalink**) 02-07-2011

Most anodes have brass caps,at least all I have seen.Are you sure there are anodes? marc

sailingdog · #3 (**permalink**) 02-07-2011

Can you post a photo of the problem...I don't think they're anode plugs.

catamount · #4 (**permalink**) 02-07-2011

On my 2QM15, the anode plugs are steel.

I think an impact driver could potentially be used to good effect, but I just pulled mine last week using a good amount of heat and a very tight fitting wrench (e.g. an adjustable crescent wrench set just too small but then hammered on to the flat's of the plug, with a little bit of pipe extender on the handle).

Actually, one one of the plugs the flats were in such bad shape that I used a pipe wrench to grab it.

hellosailor · #5 (**permalink**) 02-07-2011

Zinc doesn't rust.

But assuming you have rusted plugs and they do need to be removed..spray them with PBlaster from any auto chain store. This is not a lubricant like WD-40, it chemically attacks rust. Spray, wait 15 minutes, spray again, wait again. The plugs should come out like they were brand new clean metal.

An impact driver is probably safe but Pblaster is safer.

If that doesn't work, you can also make a slush out of crushed dry ice and alcohol. Apply the slush over the rusted part with a rag, allow to cold soak for 10-15 minutes until the area is nice and frosty. Try to unscrew. Allow to warm up (or gently torch it, remembering that alcohol vapors burn nastily) and repeat 2-3x if needed. Cold cycling like that tends to unstuck the most stubborn parts, no impacts needed.

HUGOSALT · #6 (**permalink**) 02-07-2011

As hellosailor has posted above, I have used dry ice
as last resort option after trying usual methods...
key for me was isolating dry ice
on part and cycling if needed. Always worked, never any
damage.

casey1999 · #7 (**permalink**) 02-07-2011

Quote:

Originally Posted by sailingdog

Can you post a photo of the problem...I don't think they're anode plugs.

I do not have a pic, but they are definitely anode plugs. These are on a Ynamar 3gmd. There is one in the head I got off with dificulty using pb blaster and a socket wrench and tapped with a hammer on the bar to break it lose. The threads were heavly corroded which caused the plug to be so hard to get off. The two plugs in the block are very hard to remove. I had a 2 foot extension on the socket wrench and after using penetrating oil I thought the plug was finally unscrewing. But what I found it that the plug head where the socket goes on was rounding off. I am not sure the material of the plug. It might be brass- I need to put a magnet on it to make sure it is not steel. the plug head is very strong as it is large (15/16 inch socket required) The way the yanmar plugs work on the 2 GMD and 3 GMD is that there is a plug (looks like an oil drain plug with a hex head). A 15/16 inch socket will fit the hex head perfectly. Once the plug is removed the anode srews into the part of the plug that is internal to the engine.

I used a yanmar repair manual to locate the 3 plugs in the 3GMD (the 2MGD engine has 1 plug in the head and 1 in the block). I know for sure I am on the right plugs (the plugs are located between the vertical cylinder of the block- that is why a GM1D has only a head plug and a 2gmd has one block plug and the 3gmd has two block anode plugs)

I have been working on old cars for 30 years and have delt with many rusted bolts but never had so much trouble trying to remove these plugs. I am told to put a torch to it to try to break it loose but I am a little afraind because of fire danger (engine in boat in a cramped area), heat may weaken block or change the cast iron properties- the engine is sea water cooled and 30 years old so hard to tell how thick the remaing block may really be, or the heat may change the carbon content of this old block in the area heated and cause it to corrode faster. I plan to try some dry ice held to the plug (contract its size) then put a wrench to it.

If removing fails I could try to drill out- but I might damage the block. Other option I am thinking is to leave the plug in and drill and tap the plug to except a 1/8 inch pencil anode. Since this anode is much smaller I probably would need to change it a lot.

I would really like to just get the plug out, but maybe that will have to wait to the day the engine is pulled and it is a little easier to work on.

One thing for sure when I reinstall the plug it will get a lot of antisieze!

Any comments would be appreciated,
Thanks

casey1999 · #8 (**permalink**) 02-07-2011

I think I will try to get some dry ice and give it a shot,
Thanks

catamount · #9 (**permalink**) 02-07-2011

The hex head on your plugs are probably metric, not 15/16, so you might double check just how well your sockets are really fitting. My engine had square-headed plugs, rather than hex head, thus the hammered-on crescent wrench and/or pipe wrench (we didn't have any 12-point sockets that fit really well). Anyway, make sure whatever tool you're using fits really really well.

In my case, I used the heat on the plug itself, not the part the plug was in. Neither of my plugs were directly in the engine block itself, but rather screwed into parts bolted onto the block or the cylinder head.

Certainly heating the plug expands it, and you would think it would make it more difficult to remove, not easier, but I believe the heat helps to break down the rust, and in addition, after the plug cools it shrinks.

I find that alternating heat and PB Blaster (or equivalent) works pretty well. Spray the solvent, heat until the solvent starts smoking, spray more solvent into the hot joint, repeat. I believe the combination of heat and solvent helps the solvent penetrate the joint (reduces viscosity, etc...) and helps it break down the rust more quickly (reaction kinetics, etc...).

casey1999 · #10 (**permalink**) 02-07-2011

Quote:

Originally Posted by catamount

The hex head on your plugs are probably metric, not 15/16, so you might double check just how well your sockets are really fitting. My engine had square-headed plugs, rather than hex head, thus the hammered-on crescent wrench and/or pipe wrench (we didn't have any 12-point sockets that fit really well). Anyway, make sure whatever tool you're using fits really really well.

In my case, I used the heat on the plug itself, not the part the plug was in. Neither of my plugs were directly in the engine block itself, but rather screwed into parts bolted onto the block or the cylinder head.

Certainly heating the plug expands it, and you would think it would make it more difficult to remove, not easier, but I believe the heat helps to break down the rust, and in addition, after the plug cools it shrinks.

I find that alternating heat and PB Blaster (or equivalent) works pretty well. Spray the solvent, heat until the solvent starts smoking, spray more solvent into the hot joint, repeat. I believe the combination of heat and solvent helps the solvent penetrate the joint (reduces viscosity, etc...) and helps it break down the rust more quickly (reaction kinetics, etc...).

Sounds like a good option. The socket I used while not metric (and the plug is metric) was actually several thousands of and inch smaller than the metric equivalent socket (and the plug is metric). The socket I used was a 6 point and laser cut so it fit competely on the hex head and was really tight. if I tap it in and I do not need a lot of torque to turn the plug it might still fit- I will give it a try when I get some time in the next few weeks.
thanks