1998 XJ 4.0 227k miles. I tried running a garden hose through both ways, but nothing helped. I've read that people have used CLR or similar products to try and break the crud down a bit? But I think mine might be a little too far gone. I've also thought about trying to burp compressed air through the system? I'm definitely not going to waste the time removing the dash to replace the core because it's not cold here in Florida that often, but I would like everything to work. Any ideas would be appreciated.

 

You can use the CLR or other actual radiator flush. I'd take and raise the hoses up so that once you get it into the HC, you can let it sit for a while. Let it sit then flush it out good with water. Do this a few times and see if it helps.

 

Ok, I'll give that a try this week..

 

give us an update when you do this..

 

If you core is that clogged I would flush the **** out of the radiator and the block sooner then later.. There has got to be a lot of crap in there..

 

That's true, I hadn't really thought about that. I will update when I try at it again.

 

The CLR website FAQ (http://www.jelmar.com/faq.htm) says "do not use CLR in a radiator". The heater core is a small radiator.

 

I had a local lube shop do a coolant flush for me here... costs me 60 bucks i think... they flushed it pretty well!! If i was to buy the coolant myself.. I wouldn't have saved much money.. and made a mess and disposal blah blah

I had them do that regardless because it was a new to me XJ and the cold was comings so I wanted to verify that I had a 50/50 mix

But now I have leaks.. so the whole cooling system is getting replaced!

 

You might want to use a water hose / compressed air method... back-flush with water until its a clear steady stream... then unhook and shoot some light bursts of compressed air through it.. re hook water hose and repeat a few times...

Some old timer once came in the shop and talked about running coca-cola through his heater core... I wanted to laugh at him... but then I actually started to ponder if that would even work? lol

edit: just googled it... seems people are trying it

 

I'll try anything at this point hah. I tried for a good 20 minutes trying to force water through either hose and couldn't even get a dribble out of the opposite end..

 

I never thought of using Coke to clean out a heater core. I know that, back in the day, when I was in field artillery, we used Coke to clean the bore of our 105mm Howitzers. It worked very well because of all the acid in it. It just might work or, it could just eat it up. Flush the whole system with a "real" cooling system flush. Just don't use too much water pressure when flushing it out.

 

Those two things related you think?

These flushes, whether it be radiator or transmissions, are done by people who do not own the vehicle..they will use whatever they think will do the job...am not a huge fan of those places..