CowboyXJ

A year ago I had a 99 Durango with over heating issues. At first I thought it was the fan. So I switched to dual electric. While checking the air flow on the fans I noticed the lower half of the radiator was cold. So I decided it was clogged, since the previous owner ran water. I bought almost ever flush I could and non of them worked so I pulled the rad, and gave it a CLR flush. Hooked a circulation pump to the inlet and outlet then filled it with CLR. Let it set for a day the with a flat board gave it a few taps to loosen the build up. Flushed the CLR out and installed it. Worked like a charm.
Now my 94 XJ has a new thermo, and water pump. It runs 210-220 in traffic or idle some times drops lower but most the time 180-220.
I noticed after installing the new pump that my coolant is rust colored. And I'm getting a lot of settlement in the res.
Could I use CLR as a flush on the XJ rad.
I wouldn't flush the block with it just the rad.

The Rooster

Do you have a full metal rad or one with plastic end caps ?

CowboyXJ

Plastic end caps.

djb383

Read the FAQ section on the CLR web site......it says don't use CLR in a auto cooling system (plastic tanks or not).

Salden Hund

What about an Engine flush? and the rust color after your new pump instal. I replaced Pump, T stat an housing and disconnected from heater core with an in-line rad cap (im runnin a 90' IL6). I noticed a little rust color with a good green several months down the road. Temp sits almost always 190-210 regardless. Have you found a way to prevent/reduce rust buildup?

RTorrez1

Personally I wouldn't recommend using CLR for the radiator or heater core. But A few people on here have used it and said it works. Like I said I Wouldn't recommend it.

Agent_Oragnge

keep in mind that the block is cast... it's going to have rust. Iron+oxygen+water = you guessed it! just flush with water to remove the debris and let the XJ be an XJ man.

Fishy Xj

CLR worked for my heater core, but every vehicle is different. So I guess I agree with Torrez

outersketcher

I had an '86 Honda Accord with badly rusted fluid in the radiator. My mechanic told me to pour in half a cup of Tide laundry soap (the granulated powder kind-NOT the liquid) directly into the radiator and drive it like that for at least 500 miles, then flush it. He said it would scour the insides clean of rust.

I did as he said... and holy_freaken_cow... it worked.

I don't know if this is the solution for you, but it worked on that little Accord.

djb383

There's no question that CLR works (dissolves calcium, lime, rust on metal that's been exposed to water).......the problem with CLR in a automotive cooling system, if not 100% removed, is that it continues to work.......eat/dissolve whatever it's in contact with, mainly very thin metal components in a automotive cooling system. My guess the reason why the CLR website says don't use in autos, is that they can't guarantee 100% removal from a cooling system.

When it comes to cooling system components, most vehicles are the same.

CowboyXJ

Sorry have not replied. I ended up selling the XJ before I had the chance to use the CLR. I ended up buying a 03 TJ.
If one does use CLR flush it out really good. Then after a few hrs of running it with coolant. Flush again.
Just my thoughts.

DFlintstone

A couple years ago I tried a pretty weak solution for maybe 1/2 hr. in my heater core. I didn't notice any color or crap on the bucket after. It might be that repeating might do more...I get enough heat, just not too much.

My thought for the thread is, I might try it hot or warm, high strength (overnight), as a last shot before swapping the heater core...

Any volunteers/guenipigs! (btw I'm not sure I don't have a mouse nest in there blocking 1/2 the air through the core)

ALSO, I found an aluminum T-stat housing with a 7/16 ID on the heater output tube. As opposed to a much smaller one on a cast iron one. That's going in Sunday probably.

Radi

Your guess is most probably correct. Same reason the over-the-counter radiator flush solutions have been neutered into ineffectiveness over the years. Too many people buy them, dump it in and forget about it until their cooling system falls apart. Then they sue.
In any other application, shower heads, coffee pots, etc the CLR is constantly being flushed back out, leaving it in there for 6 months isn't likely. They aren't closed, recirculating systems like in a vehicle. It probably just isn't worth the liability to the CLR folks for a $3.50 sale.

Salden Hund

What about running a few tbl spoons of baking powder after the clr. That'll neutralize the Clr during a flush.

djb383

If it was 100% certain the baking soda would 100% neutralize the CLR remaining in the cooling system, my guess is CLR would say so on their website. Like Radi said, probably not worth a $3.50 sale to CLR/Jenmar, so they remove themselves from liability by saying don't use it in a auto cooling system.