Re-fitting engine anodes

Piers

Piers

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It's just been suggested that I smear dielectric grease around the threads of an engine anode before fitting. Two reasons. One, to make removal easier; two, to prevent the inevitable slight corrosion twixt the two metals.

My thought has always been that this would prevent good electrical contact, but I'm assured it won't.

Any thoughts on the subject? Thank you,

Piers
 
Mixed thoughts here. The mounting bolts would still make good contact and dialectric grease is designed to reduce electrical conductivity so it would in fact help prevent dissimilar metal corrosion around the edges (but this would still happen on the mounting bolts). It sounds like a good idea but I'm sure there is something here I haven't thought of yet. :-).
Piers said:
It's just been suggested that I smear dielectric grease around the threads of an engine anode before fitting. Two reasons. One, to make removal easier; two, to prevent the inevitable slight corrosion twixt the two metals.

My thought has always been that this would prevent good electrical contact, but I'm assured it won't.

Any thoughts on the subject? Thank you,

Piers
Click to expand...
 
On an engine pencil anode, I think its a daft idea. You don't want to insulate either of the two threads (that is, the thread in the zinc, and the thread in the plug by which it screws into its mounting point) so that means you shouldn't use dielectric grease. If you did successfully insulate, you'd kill the functionality of the node

But all that said there is no way dielectric grease will insulate a metal thread done up hard, as is admitted by the person giving you the advice. There are too many points of metal-to metal contact. So if it isn't insulating, why use it? Why not use ordinary grease and not suffer the potential for a bit of unwanted electrical insulation and a weaker electrical connection within the thread? It's like wearing a parachute for your shipping trip to Sainsbury's - you don't need it, and the fact it wont do any harm doesn't make it a sensible idea

The corrosion point is nuts - there wouldn't be a problem removing an engine anode plug with a 19mm or whatever spanner even if the thing had sat in davy jones locker for the last 10 years. It's brass into cast iron in a nice engine room - dead easy to remove whether you use a bit of ordinary grease or not
 
Piers,

Your Cummins C Series engines have 1/2 NPT brass plugs with threaded zinc pencil anode.

NPT National Pipe Thread is a taper thread and SHOULD seal effectively in the alloy CAC housing however you can get green staining around the brass plug so normal practice is to use something like liquid PTFE to effect perfect seal. On one U.S. website there were dissenters to this practice on the grounds that PTFE insulated the anode, I had a real fight to assure people that if one studied the taper thread form in detail, despite the presence of sealant the taper thread does not prevent the shoulders of the taper making metal to metal contact when torqued up.

Another tip is the anodes themselves, not sure what Cummins charge these days but ten years ago I thought pricing was outrageous. Part of the issue is that Cummins only sell anode and brass plug as a unit. ASAP, Aquafax and Zincsmart all sell brass plugs and pencil anodes separately the zinc pencils alone cost less than £6 each.

Another black mark for Cummins is that Operation & Maintenance does not list CAC strip, clean and test as a service routine. Personally I would do it every three years and certainly not leave it more than five years.
 
Piers,

Cleaning with Rydlyme is OK but................

If you take a look at an industrial compressor the tank says 'drain daily'.

Your turbocharger or turbo-compressor is compressing air with high moisture content, add small amount of oil carryover and over time sludge is formed. For some reason people forget the air side.

I still contend that there is no substitute for stripping cleaning and pressure testing your CAC at MAXIMUM of 5 year intervals.

Take a look at.........http://www.sbmar.com/articles/aftercooler-condensation-a-different-way-to-look-at-air/
 
Would tend to agree with LS1 ( to frightened to not to :)) .Anecdotally every time I changed the air filters on VP kad 300 ,s I noticed oil sludge in the filter housing .Filters pretty black and seeming gunked up with oil residue .
This is different from car air filters that are just dry and dusty ..
So oil seems to get airside with this set up of VP.

Anode issue not all engine set ups have "pencil anodes " all over the place with associated issues .
My MAN,s I think have none ? ( although happy to be corrected ) -
Seemingly there are two mother f**cker anodes attached to the transome -theses inside the boat look like they via the through bolt attach to two hefty 3cm x 1cm copper strips that run in the bilge to the E / room -the engines are tethered to this copper strip .
So I,am I right in thinking that this set up is an alternative to loads of annual replacable "pencil anodes "
Deliberately fitted in awkward to reach areas :)
Here's a pic of two anodes on the transome
null_zpshtydbobp.jpg


Are there two systems to tackle this engine anode issue ?
 
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I dount transom anodes will do much to stop galv corrosion inside the engine's seawater passages in the main heat exchangers, CAC and fuel cooler. MAN might have decided it just isn't a propblem
 
jfm said:
I dount transom anodes will do much to stop galv corrosion inside the engine's seawater passages in the main heat exchangers, CAC and fuel cooler. MAN might have decided it just isn't a propblem
Click to expand...

Agreed if the sea water contactable components that you list are made of noble metals or something else that basically do not corrode .Don,t know I suspect unlikely ?
But there is a huge copper strip - like a church lightening conductor that connect those anodes to the engines ,which is suggestive transome anodes are sacrificed at the expense of ----- what ?

There's also a metal plate ,not replaceable under the hull exposed to the water / near the main engine scoups -inside the boat wires are bolted ,a kinda "earth " -but boat electrics are a mystery to me :)
That gadget may have nowt to do with anode protection of the engines .

Just wondering how none "pencil anoded " engines are protected ? --- don,t know. Anybody know ?

Generator air water cooler has a pencil anode .
Air con seawater H/E had a pencil anode too .
 
Portofino said:
Agreed if the sea water contactable components that you list are made of noble metals or something else that basically do not corrode .Don,t know I suspect unlikely ?
But there is a huge copper strip - like a church lightening conductor that connect those anodes to the engines ,which is suggestive transome anodes are sacrificed at the expense of ----- what ?

There's also a metal plate ,not replaceable under the hull exposed to the water / near the main engine scoups -inside the boat wires are bolted ,a kinda "earth " -but boat electrics are a mystery to me :)
That gadget may have nowt to do with anode protection of the engines .

Just wondering how none "pencil anoded " engines are protected ? --- don,t know. Anybody know ?

Generator air water cooler has a pencil anode .
Air con seawater H/E had a pencil anode too .
Click to expand...
I don't get the point of a copper connection of such dimensions. Happy to be educated on that but afaik the other 99.9% of boats on the planet don't have it. If the plan is to use the transom anodes to protect the insides of say the CAC, a plan that seems very odd, then having a massive lightening rod-ish copper conductor rather than say a more normal 16 or 10mm2 cable isn't going to make any difference. Anyway it all seems to be working portofino so if it ain't broke it probably doesn't need fixing :-)

The plate is your earth plate. Your AC ground goes to here. Plenty of boats use a P bracket for this; either solution is good.
 
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