Cooling system flush - rust remover?

The only guaranteed way is to strip the motor and get it acid bathed.

No flushing solution is going to help. At best you can pull out all the core plugs out of the block - chances are they'll be porous now anyway, run a hose in and just keep the water running. A replacement set of core plugs shouldn't be more than a few quid.

My first thought then, is what acid do they use? If it works on an entire engine, presumably it would also work by pouring it into the waterways. Or is there also heat involved?

I'm not going to give up that easily... ... even if I just fill it with Coca Cola and leave it for a day or two.

That's a good point. The core plugs don't actually look very old, so I wasn't going to change them unless I had to. But as you say, they'll be cheap enough and it'd be handy to see what's behind them.

SteveH posted something a few days ago about the wonderous abilities of vinegar- some guy used to to clean up some driveshafts and it was

=================================== If it's cast iron (not aluminium) then caustic soda will probably work. You can buy it in tins from hardware shops and some chemists. Make a strong solution (instructions on tin) and pour *slowly* into the waterways to avoid any blowback. Wear protective glasses or a head shield. Leave to stand and repeat if necessary. Don't remove the welch plugs for this job although it might make sense to renew them for final cold water flushing.

Cic.

Thanks Cic, reckon I'll give this a try. Would you expect the water pump seals to suffer from the caustic solution? I.e. should I remove the water pump and blank off the hole first?

Thanks Chris for the vinegar suggestion, which'll be my second choice.

----------------------------------- I don't think the seals will suffer but if the pump is aluminium the caustic will damage it so best removed and blanked. Even if you're not bothered about the pump itself the action of caustic on aluminium might cause unwelcome chemical reactions which might hinder the main cleaning process.

Cic.

Ah, I think the pump's body is aluminium, so had better play it safe and remove it first. I can't think of any other parts likely to suffer as it's a decidedly crude old lump.

My first thought would be de-scaling solution for domestic central heating

- this includes a rust dissolver for steel radiators. Fernox have a site that gives details and most DIY places or plumbers merchants should stock it. If you fill the block jacket and then poke a wire down the holes in the head face and around the waterpump ports I'd guess this should work. I'd use that plastic coated garden fence wire. Might need a few changes of the solution, though.

Here you go:

Nah, I don't believe you! You're pulling our legs, aren't you?

The message from Willy Eckerslyke contains these words:

Not for nothing is the process of removing scale and oxides before plating called "pickling". Though they don't usually use acetic acid.

I'd take the pump off anyway. Gives you clearer access to the water jacket.

Thanks to everyone for your suggestions. I had a fiddle around, left a pint of vinegar in the waterways for a day and found that it's not nearly as bad as I'd first thought. It looks as though someone had changed the core plugs within the last few years, but they're situated very high on this engine which makes it hard/impossible to flush out all the sludge with the engine upright (i.e. still in a vehicle). So, I tipped the engine onto its side and blasted it through with a hosepipe. The head's off at the moment, so I had plenty of access.

It doesn't exactly look like new now, but is certainly clear enough for me to fit it with confidence. I haven't checked if the drain tap's clear yet, but can probably live without one anyway. These Perkins 4203 diesel engines are seriously agricultural with a reputation for going on for ever - and most are probably in a far worse state than this one was - so I'm sure it'll cope well in my Land Rover, with a new radiator filled with decent anti-freeze.

We used to use phosphoric acid. But to be honest if it flows with a hosepipe it's probably fine, a new waterpumps probaly more value for money.

That's cos acetic acid is relatively expensive, I use caustic soda & a 12v battery.

That's the basis of Jenolite, etc, isn't it?

Yes, most of the crud's out so I'm happy with it.

Hmm, I'm not sure if they're easy to find for these old Perkins engines. There's a Land Rover on eBay at the moment with one that the seller claims runs well but that the water pump's leaking, leading me to be a bit dubious.