Coolant flush question

[Bagoftrix]

Talking to a fellow car enthusiast and he told me how well CLR house hold cleaner worked at cleaning out all the rust that had built up in his engine block after his car sat for a few years. He added it to his coolant, ran it till warm let it sit overnight and flushed it out. I dont know about this. It has me worried. I understand that vinegar works well and won't hurt the engine. I flushed my cooling system and still have rusty coolant, so I'm looking for a way to flush it out safely. My c4 sat for a few years causing the problem.

 

[DonB]

I'd be more concerned with how it will react with the radiator and heater core. Personally, I'd go to a reputable shop like a Firestone and have them back-flush the system and put a new thermostat in.

 

[hcbph]

I've used CLR on some bathroom fixtures plus a rechromed bumper that started rusting through the chrome (which was very temporary in nature). I honestly don't think I'd use it inside a cooling system, but then again I've never tried it before.

 

[Hib Halverson]

Read the label on the container.

If you read anything that says do not use this product on aluminum, DO NOT put it in your cooling system.

 

[6speeder]

Coolant flush

To perform a thorough flush, you must remove the knock sensors (if you have 2) located in
the bottom of the block. It helps if you have an L-shaped hose nozzle, or tube/hose extension, that fits inside the
knock sensor hole.

You will find that there is a considerable build-up of sediment in the bottom
of the block, especially if the coolant hasn't been regularly flushed/changed.
Several pressure flushes in that area may be required. Just the normal draining
of coolant will not remove the sediment from the bottom of the block.
Don't rush this process.

Now would be a good time to replace the knock sensors, and radiator cap, if they haven't been recently changed.