What to do to clean the water passages in a rusty block?? d4400

Using a acid is the best way, I use Citric Acid which is just a food preservative and it is brilliant though works best in warmer conditions and over several days, Cat sell 2 acid cleaners, one is a fast acting acid that requires a flush after several hours, the other I suspect is Citric Acid as they say to leave it in the system for several days before flushing. Use half a cup of a good dishwasher powder in the water for the final clean, that will remove any old oil and grease too.

Mike

While various chemical treatments will remove some rust and scale they do little to attack the heavy deposits that build up in the lower cooling section of the block.

Not much you can do about it at this point, but the seals at the base of the undisturbed cylinder sleeves may be dried out and cracking. A thorough cleaning may just mean there is nothing left that might collect around the seals and stop/slow the leaks. Still need to flush it out if you can but don't be surprised.

I had that happen when I flushed water in the block drain hole during a radiator cleaning. Went from a tight cooling system which had never leaked to a leak so fast I could watch the level of water dropping in the radiator neck! In the end i was able to use a radiator stopleak product to replace the sediment and rust i had washed away from the base of the liners. After that treatment and an oil change, the tractor ran well and stayed leak free for a couple years. When it started getting moisture in the engine crankcase again I assumed it was the seals leaking again but in the end I discovered a rusted out freeze/casting core plug under the valve cover on the head.

Ok the liner I pulled out had good newer o rings on it, and there was no signs that there was a leak in the liner seals. I would have to think all the liners were fit at the same time with new seals as thay all had the same wear( not much if any.) I am a little afraid of acid , I don't want to remove the rust around the liner seals or I might have a water problem. I think I will go with air and then a good water flush

Just remember that lower water passage between the main motor and the pilot motor is very small, as are the water passages in the pilot motor itself, and it is very easy to choke them with simply swirling crud around. Citric Acid is very benign, you probably drink it every day as it is used in most sodas as a preservative and I use it a lot on my old Cats, I remember helping my Mum as a kid make lemon cordial with both citric and tartaric acids as ingredients, I don't even use gloves even when handling the citric acid powder though my hands are pretty tough, in fact I have some citric acid solution in my RD4 engine right now that I'm about to fire up after breakfast and get discing with that tractor, use about a cup of citric acid powder dissolved in a bucket of hot water, then add cold water to fill the system, you will be amazed at how that acid just dissolves old rust away but it will take up to a week in cold weather.

I'd think about removing your pilot motor heads before cleaning because that will allow you to blow water and air to back flush through the system, plus better clean the pilot motor cooling passages, you can re-use the pilot head gaskets.
Mike

Thanks I didn't think about the pony engine, It could be a bad deal if I drove the crud into there. I think I will remove the pony heads and make 2 plates to fit where the heads were and blow the air in there first then switch over to water flush, and then I will rig up a pump to clean the jackets with the citric acid. Where do you buy it? Thanks....WA7OPY

You can buy citric acid from drugstores, Walmart, Amazon and a range of food additive wholesalers. Citric acid is regularly added to many processed foods as an anti-oxidant. It's used in bread-making and often called "bread improver".
It's also used by craft-type people who manufacture home-made soap and "bath bombs". The citric acid is what gives bath bombs their fizz.

Here's a short list of some other sources;

Bulk Apothecary
Bulk Foods
Duda Diesel
National Chemicals
Nuts.com
The Sage
Soap Goods
Wholespice

I purchased a bulk paper bag of citric acid many years ago from a food additive wholesaler, I seem to recall it was about a 20lbs bag.
This bag was produced by the Archer-Daniels-Midland Company of Illinois, and I'm sure they still produce the same product. It's much cheaper to buy it in bulk, and it lasts for years if kept in a cool, dry, dark place.

You could try a mixture of Molasses and water , Its very good at dissolving rust of steel etc . Ive soaked metal objects in a brew for several l weeks and its cleans it up beautifuly , No rust left at all just clean bear metal so it should clean out a block very well ..