Flushing with DAWN before a radiator swap.
 

1989 XJ 4x4 Auto 4.0 102,000 miles

Well I have a pin hole leak in my radiator wich is about to get me in traffic and town. So obviously I am going to change it.

However, I have flushed this jeep with water until it has ran clear befor but then when I put the hoses on a drive it for a few days it gets back brown. I have never used anything other than water.

I was thinking about putting a little DAWN detergent in it and just driving until temps going home & letting water out. REPEAT a few times. Then do a clear water flush. Then replace radiator with anitfreeze.

Is this OK? Will it hurt the 1.5 year old head gasket? Not concerned about the radiator because I'm changing it anyway. The old man I got this jeep from let it set with no antifreeze in it for a long time. It only had 78,000 miles when I got it.

Also I know it's the block that's dirtt because all radiator & heater hoses are new. The water pump has maybe 20,000 miles. The radiator was basically new when I put it in. When I get everything put back together I am finally going to replace that fan shroud that I broke hahaha.

In my opinion, Dawn won't break up the rust. You'd be better off with a chemical flush designed to break it up. Also, there are block drain plugs just above the oil pan on the driver's side that can be pulled and cleaned out to get the "trash" out of the block. I believe they are located between #2&#3, and #4&#5 cylinders. They are a taper pipe thread with a hex head. Nothing may come out when you remove them and you'll have to probe them with a screwdriver to get them open. You'd be amazed at what can build up in a block after running just water. Chemically speaking, antifreeze cools better than water and has anti-rust components in it.

You probably already know that. Just saying.

Oh yeah I know about antifreeze vs. Water. I run some antifreeze in my Jeep. When I said I only ever flushed with water I didn't mean I run water all the time.

Those freeze plugs are really hard to get to with the manifolds in the way so I don't know if I will go that far (I may regret it in another couple years haha).

Thank you for the quick reply, what chemical flush do you suggest. PRESTONE flush a good one? I just want to get as much out as possible before doing another radiator.

Why would you pull the freeze plugs? I'm talking about threaded pipe plugs underneath the freeze plugs. The freeze plugs aren't at the bottom of the water jacket anyway. Sheesh! Don't make it harder than it is!

You said the PO had run just water. Prestone is a good one, although they don't make the dry 2-part anymore as far as I know. That one worked great. That was a caustic soda that you run for an hour, then drained and added the neutralizer and ran for 1/2 hour, drained and flushed with clear water. I've seen chunks come out using that one. We had to backflush the radiator and heater core to make sure there weren't any chunks in them.

Sorry dude, when you said drain plug....my mind went to freeze plug. I seen a massive wreck today. The person I was helping move tried to follow me and got plowed so I'm a little scattered.

And the previous owner didn't run just water as far as I know. He let it sit empty with nothing is what I meant. I understand how you thought I meant straight water. Anyway thank you for your advice. I will go get the stuff tomorrow and start flushin.....