Coating Interior Rocker Cover - Thoughts ?

[Alec Pringle]

Not a TR query but a Humber question - as in the Super Snipe engine that Jeff and yours truly are currently refreshing.

 

For those unfamiliar with the Armstrong-Siddeley derived Big Six, it's huge, and dwarfs a TR lump . . . . as in 36" from flywheel to fan, for example. The engine is also considerably more advanced than a TR, achieving the same 45bhp/litre from a single Zenith downdraught rather than twin SUs back in 1958. The hemi combustion chambers and twin rocker shafts require a large rocker cover, just over 27" x 9" x 4" in fact.

 

At first glance you'd think this was a twin cam engine, complete with centre spark plugs, but the bulges cover rocker shafts not cams. Remarkably, the lubrication system, all 18 pints of it, does not fling around sufficient oil at the top to liberally coat all the interior of the rocker cover. So a combination of short runs for the first 20 years of its life, and long term storage in later life, resulted in condensation causing rust over the inside of the rocker cover.

 

I've dumped it in a bath of milkstone remover which has removed the worst of the brown stuff. Then scrubbed it with steel wool . . . . but I can't get at the areas behind the baffle plates, other than pressure washer blast. So how do I best seal the now relatively clean surface ?

 

I'm not going to paint it, as it was originally . . . . future paint flakes in the oil system I can live without, end of. Forget Glyptol or anything similar, thanks a bunch.

 

But, I would like to minimise future opportunity for further internal corrosion. Coating with petroleum jelly was Stuart's suggestion. Other thoughts that cross my mind include spraying the interior with PTFE grease, or with graphite grease . . . . something that will effectively bond to bare and to mildly rusty metal alike.

 

Any helpful thoughts from fellow Forumites, please ?

 

Cheers

 

Alec

[oldtuckunder]

Drop in into your nearest commercial platers and get them to bung it in with the next batch of passive plating, to a vast extent it doesn't matter what as its all non wearing. Things like my sump, timing chain cover, rocker cover (at just about everything else I could strip) I had cad plated about 40 years ago and every time when stripped just needs a wash and comes out looking like new.

 

Alan

[Fireman049]

Hi Alec ~

 

I withdrew my reply as I noted that you don't want to paint the inside.

Tom.

Edited March 18, 2017 by Fireman049

[Alec Pringle]

Hi Tom,

 

Glyptal and similar are fine so long as the item in question has had a good swim in a piranha tank. Perfect preparation. Anything less than 100% clean surface and forget it, sooner or later the paint will unzip . . . . .

 

Time considerations don't allow for perfect preparation, hence it's the bush engineering solutions . . . .

 

Cheers

 

Alec

[TR NIALL]

I'll go along with Alan's suggestion as above,Cheap and Cheerfull.

[BlueTR3A-5EKT]

Tha plater should run the thing through firstly a vapour degreaser then an acid pickle ( skalene ) soak to kill the rust or the coating will not 'stick'

 

Consider Nickel Pentrate as used in the gun world and on hand cuffs.....

http://www.chingfordtec.co.uk/pdf/nickel%20pentrate.pdf

 

Cheers

Peter W

 

I have seen TR2 rocker covers copper plated internally.

Edited March 19, 2017 by BlueTR3A-5EKT

[Alec Pringle]

This is the West Country . . . . . there are no local platers, the nearest are miles away, and anything takes weeks or more likely months.

 

I don't have the time.

 

The solution to this one needs to come out of a spray can in about 3 days from now !

 

Cheers

 

Alec

[BlueTR3A-5EKT]

Ther are two electroplater in Poole

https://www.yell.com/s/copper+plating-salisbury.html

[RogerH]

Hi Alec,

Frost and others do spray on 'Cad', 'Stainless' etc but these are simple colouring products and almost certainly come off.

 

Any paint system needs a perfect keyed base to be applied to to stand a chance of staying put.

 

Had you left the rust in place and removed the oil 'Bondaprimer' would have stuck nicely.

 

I'm with Pete, a metallic plated finish is needed.

 

Other wise leave as is - why should it rust in the future if used.

 

Roger

Edited March 19, 2017 by RogerH

[oldtuckunder]

Actually just had a thought based on Rogers comment, get it as clean and grease free as you can inside, get it nice and wet with water and throw it outside for 24 hours, maybe giving it the odd wetting, after 24/36 hours should have a nice bloom of rust on it, now spray it with a rust converter, something like curerust or one of the ones that goes off hard and dark. Should then have a protective surface on it that will last for decades inside te rocker cover.

 

Alan

[Alec Pringle]

Thanks Peter,

 

I do know most of the relevant local outfits, and what their timescales and reliability are like . . . . .

 

I would like to drive the blessed car again, and there is a certain time factor likely to be involved here, hence of necessity foregoing some of the solutions I might prefer to employ in an ideal world.

 

Cheers

 

Alec

[stuart]

FWIW Capital Chrome (was London Chroming) will do a 2wk turn round for me.

Edit the local platers in Launceston will do nickel plate in less than that if its any help.

Stuart.

Edited March 19, 2017 by stuart

[stillp]

Why not just give it a good oiling and use it Alec? As long as it doesn't get too many short runs, surely it won't develop enough condensation to make it rust again.

I'd be tempted to use gearbox oil, which 'clings' better that engine oil.

 

Pete

[Alec Pringle]

Thanks for all the thoughts, helped kick the grey matter into gear !

 

Having removed the worst of the rust in the bath of diluted milkstone remover, followed by brisk rubbing with the stainless steel 'pan scrubber', I've given what brown stuff remains a couple of coats of neat mr and turned brown to hard black. That's been rapidly dried by the fan heater, and will now get a spray of PTFE 'dry' lubricant which should penetrate the pores adequately. Meanwhile I've ordered a rattle can of Wurth Rost Off Black graphite grease, which I'll then coat the interior with. Those areas which do not get oil flung at them should be adequately corrosion resistant after PTFE and graphite sealing, both products having a propensity to stick like the proverbial to a blanket.

 

Externally it's a coat of old-fashioned aluminium paint, as original.

 

Cheers

 

Alec

[Ian Vincent]

Shell Ensis grease is specifically designed to prevent corrosion and is suitable for application to corroded surfaces.

 

Rgds Ian

[Don H.]

Mixing a PTFE-based grease with aa graphite grease just doesn't appeal to me (as one who's spent decades doing coatings research). I see no particular need for PTFE (or Teflon, as it's more commonly known), nor for graphite in the system.

 

The need is for barrier properties, not lubricity. A passivating coating would be my first choice -- I like that one based on the fundamental chemistry. If a corrosion-preventative treatment that isn't a conventional coating remains your choice, Alec, how about Fluid Film?

http://www.fluid-film.com/automotive-applications/

[Alec Pringle]

Rocker cover now completed . . . . . aluminium paint on the outside, inside as detailed above.

 

The PTFE/Graphite spray doesn't seem to have done any harm. Spray water at it, imitating condensation, and it simply doesn't stay there . . . . just falls off, so should at least either emulsify or vaporise rather than hanging there and continuing to corrode. Fingers crossed !

 

Next head scratch was the block - originally a very thin coating of Humber mid-blue, mainly turned black over the years, and it's not the smoothest of castings, as in all dimply as you might say ! Much cleaning with paraffin, then pressure washer water, then white spirit . . . . . but that's no substitute for a swim in the piranha tank, and I doubt that engine enamel will stick long term.

 

Brainwave solution, I tried polishing a small area with the remains of a tube of Zebrite, old fashioned stove and grate graphite polish. Just the job, semi-gloss finish that covers everything. Off to the ironmonger in the morning for a fresh tin of similar !

 

Cheers,

 

Alec

[Ben Freer]

Ahh Zebrite! I remember polishing fireplaces with the stuff! You could set the whole engine bay off with a set of well polished brass fire irons........????