Im running a 1660 xflow, and the inside of the block is well rusty, ive tried the normal radweld crap that's supposed to clean the water works, but its done nothing, so what else can I use

Via the grapevine, ive heard of vinegar or and dishwasher cleaner, but not sure about either of those

steve

Reverse flush the block to get rid of loose stuff, long wire brushes down the water holes you can see and reflush.
If a dishwasher tablet is ok in a dishwasher I can’t see it doing any harm.
What about some calgon?
As long as you don’t get anything corrosive on the block faces and start with a shorter time to see how it looks I can’t see you doing much damage to a block of cast iron.
If you do uncover a leak or hole in the block then the block was scrap in the first place.

I'm in the same boat.

Is it stripped down? If so, take it to your local engine builder for an acid bath. Should cost about £20. Once its dry you can blow the lumps out or tip it up and tap it all out. Pulling the core plugs gives you little more access.

Engine is in the car, and seems to be fine, doesn't overheat that I am aware off, but when ever I drain the water out (yearly) it comes out as a brown mess,
Ive flushed it through, and back flushed,

Steve

Maybe stupid question...
You say "water"...
Are you using plain water??
Antifreeze normally has corrosion inhibitors to prevent that.

And if you are using antifreeze, is it the correct one for iron blocks?

HTH

I did think about that after I posted it!

antifreeze every time, and suitable for iron engines,

If you have the rad etc all disconnected, you can flush the block and phosphoric acid will dissolve the rust and leave a phosphated finish (phosphoric acid is used/sold as rust converter, but if left will attack copper and probably ali radiators,and other metals)

Just get with the times and replace the engine mate ;o)

I would M8, but EVERY newer style of engine is to tall, and would mean drastic treatment to the body/bonnet/nosecone to rectify

steve

Put a scooby engine in it!

too wide

Vinegar will convert the rust into water soluble iron acetate, which can just be washed off, and repeated until residual rust is removed, leaving a bare iron surface (this surface will be quite reactive as there is no protective layer of black oxide/phosphate).
Citric acid will do similar, however iron citrate is less soluble, so will require more flushing and retreatment to remove the same amount of rust.
Phosphoric acid will convert the surface of the rust into insoluble iron phosphate, which is fine for light surface rust, however if the rust is thicker it will continue to corrode under the iron phosphate layer. This makes it fine for final rust protection, but not for removing thicker rust deposits.
Dishwasher tablets are ok for removing oil contamination, but will not remove rust.

If you're applying either acids to the engine, thorough rinsing and neutralisation with baking soda afterwards will stop any residual acid attacking gasket materials etc.
If there are heavy deposits in the water jacket, the action of the acid alone may not be sufficent to shift all the corrosion/silt deposits.
You could connect the radiator pipes together and use the water pump to circulate your chosen cleaning solution to improve the effectiveness and speed up the rust removal.

Dave

Used citric acid in the past with success run engine hot with the acid and flush. It may take serval goes.

Ive now had the engine idling for nearly two days prob about 12 hours in total, with holts rad cleaner, a dish washer cleaner, and water, and quite a bit of crud came out, plus very dirty muddy brown water

Flushed through with clean water, and ran just with water for 30 mins, emptied, and just clean came out
Flushed and back flushed several times
Refilled with TWO litres of antifreeze, manual says one litre
Re run, and all appears to be clean blue water

So I will see after a few weeks if the water is clean, as up to now, ive only ever put in one litre of antifreeze/coolant, so that could of been the issue

steve