Bukh DV10 ME pencil anode

[Gin]

In carrying out the normal 1/2 yearly, or in my case as it is such an inaccessible job, annual engine anode replacement I have a problem.

The zinc anode obviously had not wasted away completely as it has 'welded' itself into the access hole so that as I have unscrewed the brass nut, on the engine casing access point ,so the anode has been unscrewed too from the inside of the said nut- the result ? I now have an immoveable s/s screw anode post which I can just feel locked solid in the centre of the access hole and it is not possible to screw the brass nut back on even if I wanted to. The good thing is that the anode forms a watertight plug for the time being so no cooling water is lost if the engine is started.

The manufacturers, those nice people at Bukh on the South Coast, tell me that the gallery behind the plug is capacious and I should simply knock the anode and its screw post through- the zinc will disappear and the screw post lying in the bottom of the gallery will do no harm- so far so good BUT

The access point is at the rear(aft) face of the engine block- I have no rear access to the engine apart from a tiny inspection hatch which I can get only one arm and a part of a shoulder through but then have no field of view, and even when I remove the alternator and the starter motor there is very limited right- angle access from the front of the engine and even thought there is just room to swing a stubby hammer I cannot see what I am doing and so far my best efforts with hammer and screwdriver have been without success.

I want to avoid moving the engine into the cabin if possible, as that would give me a new access problem i.e. the coupling and stern gland assemblies, and I am wondering whether, as it seems unlikely that I can get enough of a swing to punch the anode through, there is some kind of (very)small hole cutter blade which,
a). will cope with the 6mm screw post being in the way
b). could be fitted to a small electric screwdriver type of thing- there is no room to use a conventional shape power drill
c). any other practical ideas

 

[mflynn1971]

Had the same problem with the same engine in the same boat. At the time rghtly or wrongly I took the view that if there was anode there I could leave well enough alone till it reduced further in size. I put the nut back on threading it over the 6mm rod and into housing. Later I decided to flush the waterways as described on this forum by Cliff and others. The mild acid solution freed up the anode and it actually fell into the 'gallery ' behind. Suggest you might try some mild acid solution externally and leave it for a while to free it up. It is a pain to get at though isnt it. I think I ended up hanging upside down.


Mike

 

[Poignard]

I made an extractor when this happened to me. I don't know how to produce a sketch on here so hope this description will do:

Take a length of studding a couple of inches long with an outside diameter sufficiently small to allow it to enter the hole in the engine block. I think I used 8 or 10mm diameter.

Using a lathe, [if you don't have one you can get it cheaply done by someone who has or you might manage it in a drill press] drill an axial hole in one end of the studding and tap it with the same thread as the stud in the anode.[ Are you sure it's 6mm diameter? I don't have one here but that seems larger than I remember. I would have thought it was 4 or 5mm, but you will have to check]

Screw the studding onto the anode stud. You now have a length of studding sticking out of the anode hole.

Place a large washer and a short length of tube, or a strip of steel bent into a u-shape, with a hole that will clear the studding, over the studding so that it bears on the engine block and acts as a bridge.

Put a nut on the studding and prevent the studding from turning with a spanner on two more nuts locked together [or grip the thread with mole grips, if you don't mind butchering the studding!].

Now tighten the first nut down onto your bridge piece, or washer, and jack out the old anode.

To avoid this happening again, I now reduce the diameter of new anodes by about 2mm before I fit them.

I could, of course, have simply knocked the old anode through into the block but my engine is very old and I've no idea how many old ones might be piled up in there!

You might say why don't I just lend you the extractor but I can't find it. It probably got binned when I started turning down new anodes!

 

[Gin]

Thanks for that, especially the acidic solution tip which, since the boat is now in the yard for winter I can attempt in the New Year.

I have some arthritic damage to finger and leg joints so my flexibility is somewhat reduced, to say the least- hanging upside down I can do but only for a few minutes at a time, so I think that's out even if I had enough access.

Since posting this request and knowing that, unlike you I cannot rescrew the brass nut back on to the anode and into the block at the same time, I thought that I could ream out the underside of the brass nut to say 8mm to the required depth of the post to overcome the re-screwing problem which would then, if else fails, enable me to make the access watertight and then check it every couple of months when afloat until such time as the zinc/post drops through.

 

[Gin]

Yes, that would certainly do it- I hadn't thought of fabricating an extractor and even with the restricted access I think this would be a viable engineering solution.

I'l try the above-mentioned acid solution first over a period and then if that doesn't do the trick get the extractor made up- Shame , I sold a Myford earlier this year which although it had worn bearings would have handled this well- there are small local machine shops around here, or were a few years back.

Good idea about reducing the size of the pencil anodes- small price to pay for not having to do this job again!!

By the way it took me an hour to extract the brass nut as I could only get a swing of about 1/16th turn on the nut which as two threads were being unwound bound up for for the whole extraction and actually caused considerable wear on the brass threads

 

[Poignard]

Been there too! Now I run a tap through to clean up the thread in the engine block! I also have to use a very short 22mm[?] spanner to get the holder out because there isn't space in my engine room to swing a full size one.

"One of these days" I'm going to make a better anode holder that you can get a socket onto.

 

[Gin]

Here is an amusing(??) update on the extractor idea.

having sold off my Myford lathe as the bearings were shot I had to resort to an engineering shop to help make the extractor.

I made a nice little drawing of a simple construction- essentially a length of 8mm threaded stud with nuts and a large washer (all of which I supplied). My request was for them to drill and tap a 5mm thread into one end and about about 10mm deep to screw onto the seized anode post. A section of tube was also requested with clearance to pass over the studding on which I could bear down with the nut/washer- a length of 10 cm mild steel would do.

A couple of days later I received a phone call from the workshop to say that "yes, we can do that job for you and it will cost ONLY £100 if you pay in cash.

Now I like to think I can see the funny side of most things but it was all I could do to refrain from exploding, but I managed to say simply that it was uneconomic and I would return to pick up my bits and pieces shortly.

I then took the same kit to my local car repairers who as it turned out have a good workshop where, for £10 (plus a drink), they drilled and tapped the studding, leaving me to scavenge for a bit of tube in due course. Oh yes, I forgot, they also drilled out the underside of the old brass plug to about 8mm with sufficient clearance so that if necessary I can use this to blank off the hole temporarily without fouling the seized/protruding anode post if this happens again

By the way what is the tap size for the screw in brass plug into which the pencil anode fits?- I shall clean mine up before refitting