Saving Old Seagulls

Phosphoric acid is a fairly 'benign' acid as acids go - this is what is in Colas which are credited with such magical derusting properties. No real place for it in Seagull restos other then for long term soak usage (at dilute concentrations) for derusting and limescale removal.

Caustic Soda - (Sodium Hydroxide) is a wonderful degreaser, but is strongly alkaline so will not work on limescale and has no derusting properties - I occasionally use it on glooped up tanks to break down the old two-strokeoil rather than use fierce mechanical methods. Use carefully- it can cause bad skin burns.
It is used in small amounts in dishwasher tablets (to degrease plates/pans obviously) which I think is why they have dire warnings on the packaging (but why it can also clean aluminium engine parts (where you wouldn't normally use Caustic) so effectively when HID is out.
Muriatic acid - can't remember now exactly, but I seem to recall that this is inhibited Hydrochloric, whereby it will go for rust but not attack the base metal - only to be used for limescale removal on non-metallic items/fittings or rust removal on cast iron.

Dont' be frightened of chemicals, but treat them with respect, take precautions - skin, eyes etc. and use the right ones on the right metals.
Not much chemistry outside of speciality chemicals that can be used for our purposes on non-ferrous parts of the engine

Test tanks - even an apparently bad one has oil floating on the surface - the water beneath can be quite clean - for cylinder 'maintenance', I run my engines using one of these car wash and wax solutions in my test tank with the theory that the water evaporates and leaves a wax film in the water jacket (as happens on a car).
Don't use household detergents as they usually contain salt and are slightly acidic. Rick.

Good post Rick, most informative. can you recomend a solution to cleaning out the water jacket on cast blocks.
Other than Kettle de-scaler (has little effect on rust ) what about brown sauce for rust removal ?

Things have to be kept in perspective to start with - we are talking about cylinders which are now a number of decades old and as a consequence will all have a degree of corrosion and lamination (or delamination), on parts which were originally cast from gutter iron! So we are all fighting a bit of a rearguard action anyway, but fortunately there is a fair amount of 'meat' on the castings to allow loss by corrosion.
Not now talking about real crusted-up blocks, but blocks which have seen a bit of action, most will often suffer from rust flakes which block smaller connections/pipes etc. - especially as Neil says - on 102 water outlets and the like, and the most immediate thing to do is to clean/flush/blow the muck out, and just stop things deteriorating from there.
Kettle descaler is I think tartaric acid - an inncuous acid used in cooking, so worst case nobody can get hurt/poisoned by missuse of it, but with the result that it doesn't have much 'go' in terms of descaling Seagull cylinders.
I have in fact used phosphoric made up as a hot solution in water in cylinder jackets, and a lot of rust is freed up for subsequent rinsing out - I wouldn't have any issues about the conversion mechanism that occurs with phosphoric and iron bearing in mind my first paragraph, but if you were, a final flush with an alkaline material (washing soda) would counter any potential ill-effects.
Brown sauce - don't know (their recipes are very secret apparently) - but I did hear of a group of vintage motorcycle who swore by (or at) molasses as a magical deruster! I am sure there are odd workable solutions out there, which would have some fundamental explanation (like the Cola/phosphoric connection). Rick.

Yo Dude ....
Yo am de man, Rick, and am in deep respeck ov da knowledge ...an big it up man
but gotta say dat me an da bloods am lookin reel odd at use of da Brown Sauce innit

like wot does we put on da bakon samiches, if you whiteys am consumin all da majic liquid to un-stick all dose, like, well old motors if-you-know-what-I-mean ..

An reely I does big it up on the respek man. but the bloods gotta have the samiches wiv da sauce for brekfas

So, brown sauce makes you talk funny then?

Seriously I have heard of it being used as a cleaning agent but not as a de ruster.

Gotta say I am of the opinion that the rust is gonna get you in the end, especially when you are using bare metal in a warm, wet possibly salty environment, all you can do is slow it down hopefully to the point that the block or whatever will out last you which shouldn't be too difficult if the waterways are clear.

My regime is flush after every use ( even in freshwater silt can trap moisture ) a wash through with a detergent then a spray of WD40 ( always understood the WD stood for Water dispersant so that seems like a good plan to me )

I am not too sure about phosphoric acid, I remember the product called Curust or was it Kurust? not sure if its still available, anyway that used to chemically convert the rust which turned black so is likely to be something similar perhaps? anyway, whenever I used it I would clean off as much rust as poss then paint it on. Magically it would turn black but I always found there was evidence of good old brown rust underneath the black no matter how much you put on or how long you left it so I think its a problem of getting whatever treatment you use to 'soak in'.

The question is - you learned metallurgists - does cast iron, to a degree, form its own protective skin.

Mild steel just exchanges its exposed surface for layers of rust, aluminium can form a protective outer layer.

It would be nice to think that after rebuilding some old iron blocks with iron manifolds, iron water pumps, iron thermostat housings and iron inlet manifolds which will have raw water pumped through them, they might outlast me.

I have about 15 useful years left. The blocks are now 29 years old.

This is a question for a metallurgist, a soothsayer, a sociologist, a psychologist and a meteorologist( will global warming increase the salinity in the tidal estuary?) . . .

A soothsayer says when is the Lerryn race R.B.T.?

H-A

(Do I still have time to build the 24 footer?)

I told you - its too long to go round that buoy, and you will be disqualified, of which I have sufficient experience.
Now as you heathens who live many motorways from the land of milk and honey would not know the various tides from which to chose around Christmas, I shall copy and send send off the December Fowey tide table (via that v.stressful bloody Photo bloody Bucket)

R.B.T, Can you not just speak to the man who runs the race and give us a day when we would need to be there?

Better still there is a second chance to bring your SD up to the end of season meeting on the Thames, Wood bloke will stick some more charcoal on the Barby

H-A

(A date would be good as us distant folk need to book expensive Fowey pads), and book tables at Sams for top seafood, OK yar

RBT - just picked up on your post re cast iron, salt etc. - all bad news I'm afraid. Cast iron doesn't form its own protective layer, so all of your iron internals will be quietly rusting - but over a long ('ish) period so don't lose sleep over it.
Aluminium self-anodises through oxidation, but leaves you with that powdery texture.
Salt water in estuaries - don't know about your location, (think the Fal is v.deep and high flow), but in some estuarine situations, salt concentration increases above normal sea levels due to tidal flow, evaporation and similar factors, which is why salt extraction goes on at such places - eg. Maldon.
But on the bright side, you will float higher if you fall in!! Rick.

Lysergic Acid Diethylamide - now thats the one to use -

- LSD. Looking at some of these extenuated threads to posts, some of those scholarly stationary engine polishers must be on it . . .

Any one tried CILIT BANG ?????? A mate of mine uses it for most grubby projects but beware it eats paint if left on too long. May not be avalable in the southern hemesphere under that name.

In my SCUBA diving days, we used to use Citric Acid (ex brewing supplies shops) to remove marine concretion from recovered artifacts. I still use it to clean furred kettles. Tablespoonful to a pint.

Welsh water will also clean furred kettles if you're not in a rush - so regular flushing of the engine in a test tank full of their soft water - or rain water (contains carbonic acid) - will help to keep the chalk away.

On another forum, the guys there swear by Fernox DS3 Limescale Remover for clearing out raw water cooled marine engines. It costs around £15-20 for 2kg. It's designed for de-scaling central heating systems, so it'll only work really well if the solution is HOT and allowed to furcle around for an hour or so - so you need to figure out a way of re-circulating the soup. Alleged to change colour when exhausted.

Using DS3 might be a better approach than pulling the head off if you've got a blocked jacket ? (assuming that at least a dribble can get through of course)

Fernox DS3 is designed to remove limescale in combi central heating boiler heat exchangers in hard water areas & to be not aggressive toward copper, aluminium, stainless steel & cast iron, boiler components.

Seagull water jackets tend to bel full of a hard concretion of rust big rust flakes & salt acting as a very good glue, holding the whole lot in a solid mass.

I've never tried DS3 but have plenty, I will try dropping bits of concretion from a broken water jacket cylinder into a glass of saturated DS3, it's going to get started before 1600 19 Oct 09, remind me to check in a couple of days.

Started at 1535 with a saturated solution of warm DS3, added concretion, started to mildly fizz but not from all over concretion, stopped after 5 mins, DS3 solution changed in colour from clear, dark urine, to dirty rusty water on stirring.

1930 As no signs of any form of reaction, moved glass in to bowl of hot water to see if it helps.

Heated to as hot as my hand could stand, no reaction.

24 hours now & it's been heated several times, still no signs of any reaction.
Concretion still in big lumps, but solution is now clear, sort of a light flat bitter colour