How does rust react with coolant??

[madwilly240]

My girlfriend's car runs fine when there is just water in the cooling system. When we add coolant, she loses heat, and it overheats bad.

Her entire cooling system was rusty inside and so we replaced everything (heater core, water pump, rad, all hoses, thermostat), I'm thinking maybe once coolant is introduced back into the system it breaks up the rust and clogs things up. Any Ideas?

Its a 2000 Cherokee 6 cyl

[g6civcx]

I would do a coolant flush to get rid of rust inside the engine.

[racepar1]

There is really not much you can do. The rust/gunk collects at the bottom of the water passages that are around the cylinders. You can either remove the freeze plugs and flush the block; or flush the coolant, drive it till it gets dirty, and repeat till it doesn't get dirty anymore. When people don't take care of their cooling system it is a real PITA to fix. Watch out for clogged thermostats though, all that gunk in the block tends to clog them up.

[madwilly240]

Thanks, every aspect of the cooling system has been replaced now, and it has been garden hose flushed. Running good and cool, with hot heat inside.

Jeeps are so problematic it seems. Probably just a few days til the next problem rolls around.

[racepar1]

Jeeps are notorious for rusty cooling systems! I have seen 4 or 5 that are just as you described. When one of the freeze plugs starts to leak, not IF but WHEN, you should flush the block when you replace it. Good luck!

[WILDACEX187]

are the coolant flush bottles they sell at the auto stores safe to use? i heard they eat away at seals