Removing Rust from Cooling System (Block)

[MrOizo]

Hey peoples,

In preparation of a new radiator, I have done several flushes and have managed to get the water running clear after engine running for about 20 mins.

Now i have the engine out ready for clutch and should try sort out even more if that's possible.

What's the best way to remove what ever is left in the bottom of the block? I have thought about running more water through and maybe forcing through with water blaster?
Is there a treatment that's good for this?

I have new alloy radiator and new silicone hoses so only remaining parts are block and heater core.

Thanks in advance,
Adrian.

[MAC_HATER]

Ill see if i can hassle a friend about the stuff he used in his Fiero recently

We gave it a coolant\oil flush and refresh as an attempt to make up for 20 years of neglect from previous chump change owners, and the regular off the shelf repco coolant flush stuff wasn't doing much better than plain old water

he got hold of some other stuff that's a bit more aggressive, so much so that it flushed out literal chunks and turned his entire coolant system into a colander, as the neglect was so bad that the rust was holding everything together, but this was an extreme case, your coolant system wont even be close to as bad as the Fiero so it should do a good job

[stolic]

When I was prepping my 7a block I used some rust dissolver from super cheap. breaks down all the crud and treats the good metal to prevent more rust down the track. Probably only suitable on a striped down block tho, unless you can be careful with where its going.

[MrOizo]

Thanks for suggestons, MAC_HATER and stolic.

I used the water blaster without the thermostat and really only flushed the remaining coolant in the engine. Doing this in the heater core looks to have done a good job and rusty water came out.

I have read on some other forums that CLR (Calcium, Lime, Rust) works good. Another is molasses which sounds crazy but leaving in there for weeks gives good results.

I'll wait before I get too excited and stuff the engine

Cheers.

[Jdawg]

..... Another is molasses which sounds crazy but leaving in there for weeks gives good results...
Cheers.

I read about blackstrap molasses a while ago so gave it a try. It is nothing short of spectacular as a rust dissolver.
Fill your block up and let it soak for a week
Buy it from Farm supplies place. Recommended was a 10 parts water to 1 part Molasses mix. You get left with a bit of iron sludge and the water will be slightly acidic according to those who know chemistry. It is the high levels of Potassium in it that converts the rust, which is what Rust Dissolvers use but Molasses is cheaper.

[Stott69]

What about the age old rust remover Cocacola?

[Townace]

Tablespoon or 2 of soda crystals and a 100ks or so of driving then a good flush works well

[DeeCee]

I used malt vinegar to remove rust from some small items. Wash off residue with water, dry then coat immediately with a primer of some sort.
Also, use washing up gloves to prevent skin contact with solution and some googles to prevent splashing into your eyes.