Ive been noticing some rust in my coolant, and I know there isnt a lot of actual antifreeze in the system. So i want to flush it before winter hits. Ive flushed it before with just water. but cant put anything in there to help get rid of the rust. This might be a bad idea but would CLR hurt if i just ran it through the system for 5 or 10 minutes then put in new antifreeze?

 

i'd be afraid to put pure CLR in radiator or heater core. on the label it says its harmful to aluminum. i wouldn't be afraid of pouring in a quart or so with a full system of distilled water, or even a 50/50 mix direct into the heater core.

but - what i'd do first is backflush the heater core both ways with the water hose, flush the radiator thoroughly with water hose and allow it all to drain. And most importantly - remove the block drain plugs that hide behind the engine mounts and the t-stat, and flush the block. you'll be amazed at the crap that comes out of the bottom of it. lots of heavy rusty scale.

 

As DH has mentioned, the block is where most of the rust tends to be trapped. If you are seeing a fair amount of rust in the radiator and if you have a bit of extra time, also remove all of the freeze plugs from both sides of the block and dig out the rust/muck that collects around the cylinders - then replace all of the freeze plugs with new ones - the size is 1-5/8" and refill with anti-freeze and distilled water. I get distilled water cheaply at my local Wal-Mart.

 

never replaced the freeze plugs. i was under the impression they were PITA to get to/replace. That does sound like a good idea. the motor has over 230k miles so its probably due.

How difficult is it to replace the freeze plugs?

 

tape the edge with a flat screwdriver and they spin , then grab it with vise grip and pull. in theory at least

 

Either that, or drive a screwdriver THRU them, and then just pry them out. Not really too bad of a job. Putting them in is easy. (if the engine is on a stand.....)

 

Well if the engine is on a stand, i wouldn't be as worried about it. Ill see what i can do next weekend.

 

Even with the engine in the truck, accessing the freeze plugs on the side of the block is pretty easy. When you remove the original freeze plugs, please let us know what you find.

 

Its the two on the back of the block that are going to be impossible to get. And the little one REALLY likes to rust out, and leak.

 

if the freeze plugs are in good condition (not rusted or leaking), i think its overkill to replace them. just remove the drain plugs, flush the block of all the rusty settlement and call it done.