Zinc Anode on BUKH 10 - Cobra 850

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lancelot

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Hi.
I tried to replace the zinc anode on the engine block (water jacket) but could not release the anode. The large brass nut came off the block OK. and it unscrewed from the anode, however, it would not come out. Any ideas on how to release it for changing?
Regards,
Lancelot.
 
From memory the thread will stick proud of the engine block. I screwed a couple of nuts on the thread and simply levered the anode out. I was always surprised at how little it had ever erroded.
 
Zinc anode on BUKH 1O - Cobra 850

Cheers, Meandraft.
You are right the thread, just stands proud of the block. I will try to get some smaller nuts to try.
Regards,
Lancelot
 
Don't be too violent with the pencil anode, it's quite brittle. I took mine out, was pleased to find it was not very worn and tapped it lightly to try and dislodge some scale. It snapped in two like a carrot.

Alan
 
There is plenty of room in the water jacket. You could just tap the old anode in and it will fall to the bottom of the jacket and continue protecting the metal until it disappears (except for the bit of studding).

Neil
 
Releasing pencil anode

I have just done this job on my DV10. I find that the best solution is to remove the brass nut and then use a thin penny washer over the projecting stud and then replace the brass nut (or even better a steel one). As you tighten this against the penny washer the anode gets pulled from its socket and once so loosened is relatively easy to tug out with pliers.

All this done, of course, like most engine jobs on a boat without being able to see what you are doing!

Morgan
 
Zinc Anode on BUKH 10

Cheers, Morgan.
I thought I might do that the next time I am at the boat - if the rain clears.
Regards,
Keith
 
Mine's impossible to see and almost as hard to reach on my Sadler so I've tried two methods, and a third temporary fix

First, the UK agents say the water gallery is large and it is recommended to tap it through and let it fall into the bottom of the gallery- trouble is I can't get a good swing at it and this wasn't a solution for me.

Secondly I made up a puller/extractor, with a piece of matching threaded stud and some nuts but this is difficult to fiddle into place and still have enough stud to use- probably possible with skinned fingers.

In the end, I simply reamed out the threaded underside of the 22mm brass nut, so that I could at least replace it and not risk a disastrous water leak. The intention being to let erosion of the anode continue, inspecting occasionally until I could knock it through and then replace with a new anode and a new nut (keeping the reamed out plug for next time).

However, it would be better to skim off a few thou of the pencil anode to prevent a similar recurrence I reckon.

In the end and unexpected lift-out of the engine provided the opportunity to gain easy access to the fitting and a proper replacement was made.

Now a have a new eroding anode, a plug to fit over it if it welds itself in place again and peace of mind for a season or two (they seem to last a long time), in the meantime
 
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BUKH 20

is this anything like the BUKH 20 as fitted to Konsorts, the last time I bought an engine anode for mine it was marketed for a Nannie and was very cheap, brass nut and anode complete replacement.
 
Pencil anode fun and games

QUOTE << However, it would be better to skim off a few thou of the pencil anode to prevent a similar recurrence I reckon >> QUOTE

I have tried this and regret to advise that it does not work. It certainly makes fitting the new anode easier but scale then developes between the zinc and the cast iron block so removal is just as awkward as when the anode was a snug fit. In fact if anything I think the scale "welds" the anode in even more firmly.

The penny washer and nut "puller" trick has worked every time for me. I use a socket on a long extension bar to get the wrench clear of the exhaust and just wind it out.

Morgan
 
Facing the engine, from the flywheel side, extend your left hand alongside the left hand side of the valve cover, until you reach the back of the valve cover. Let your hand drop until you find the throttle cable quadrant. Just outboard of that and slightly above there is a bolt screwed into the back of the block, with the head of the bolt facing away from you (i.e. the shank of the bolt comes into the engine block, pointing towards you). Unscrew same. The back of the bolt is drilled to take a machine screw on which is mounted a slim, cylindrical anode.

Unfortunately, the machine screw is threaded in the same direction as the bolt, so unscrewing the bolt usually unscrews the anode, leaving it in place with just the end of the thread of the anode machine screw accessible. It can then be pulled out using the various devious means discussed in this forum thread.

Unless you have an exemplary engine layout, you will not be able to see much of what you're doing, and will be working largely by touch.

It is part no 35, in section 3 of the drawing here:

http://www.tnorrismarine.co.uk/documents/Bukhdrawingpdf.pdf
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Also access to swing a spanner is usually tight, and the brass nut is quite easy to round-off if it's tight. I bought a cranked ring spanner especially, and cut the shaft down a bit to give me room to swing it. Even then I can only swing it about 30 degrees at a time.
 
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Zinc Anode on bukh 10

Wow! what a job. It took me 2 to 3 hours to get the anode out, today. I used all the suggestions from the splendid forumites - much appreciated. The little darling fought every mm. of the way. A combined effort of penny washers, pliers, grips, various spanners and flat screwdrivers to lever and prise. Oh yes some blaspheming and pleading, as well. Luckily enough, there was an old brass nut from the previous service (carried out by mechanic) left in the spares box, which I used for the levering and prising. It is truly knackered now and the new brass nut retained to use at the end. I must admit, I may have dropped a proverbial by screwing the anode into the nut before before screwing the whole assembly into place. The threaded part of the anode does not sit perfectly vertical and I feel this may have caused the brass nut to cross thread, although it is in place. I think it would be better to put the anode in first and then screw the brass nut in place. Hopefully the steel water jacket thread should be OK. and the softer brass thread has crossed, but this can be replaced next time.
The anode had not crumbled that much and could have been left a little longer. It has been in place for nearly two years.
I now need to change the fuel filters and bleed the system. Run the engine and check there is no leak from the water jacket where the brass nut is located.
Regards,
Keith
 
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