Do you think this method will clean out my greatest core as well?

 

I assume some sort of auto-spell app has afflicted the meaning of your question ?...maybe a Mohamed Ali reference?

If you mean radiator core, that would be a best case outcome, depends how bad it is...wouldnt bet my house on it

things is, if the radiator is clogged, you have to flush that coolant as clean as possible before installing a new rad, or it will be instantly restricted

same for heater core, keep it open while flushing,

If you take off the front grille, their should be a plastic plug in the radiator

 

Fat fingers, not proofreading and writing this post on my phone for the first time caused me to type greatest and not heater.

 

Just looked at your radiator cap photo again and other than all the gunk something struck me as odd. If I am recalling correctly whenever I have taken the cap off of an XJ radiator the coolant level is right at the top, up to the overflow hose that goes to the coolant reservoir/expansion tank. I am wondering if you have air in the cooling system, which could give an improper reading on the temperature gauge indicating overheating. If the hose to the tank is plugged that might restrict the normal purge of air during heat up and drawing coolant into the system from the tank during cool down. Or it might be that the cap, being full of crud, is not sealing thus preventing the system from pressurizing and more prone to having coolant boil at high temperature with resulting coolant loss. (at pressure the coolant has a higher boiling point, a good thing) These are likely not the extent of the issues but something to not evaluate. You should also clean the tank out as it likely has lots of crud in it.

 

Thanks "third coast". I agree with what you said but I will be going thru the entire system. I just have to pick a day when it's not 111 outside. After all the recommendations that everyone had said on here, I believe I can get this done properly.
I don't want to install new radiator only because I don't want the crud in it. I was thinking of having the old one steam cleaned at a radiator company and use it as my dummy. That would mean cleaning my water pump and reservoir, or should I be buying a new pump as well. With less than 16k miles on it, it should be fine right?
This isn't my dd, I bought it in 2009 and have only put 16k miles on it. Just to give you perspective.

 

Water pump should be fine with 16k miles but some low cost aftermarket pumps can be more prone to early problems. However I don't think I would be in a hurry to change if it was me unless there are other reasons to suspect it.

 

So I took the bottom plug out of the radiator on the pass. side and let it drain out. It looked like muddy brown water. Then I pulled the plug two more times while pulling the line going to the heater core and running water thru it with the engine on. Eventually the water coming out of the top of the radiator turned clear. So 3 times I did this and it started getting hot, it was 330 and almost 108. Time to get in the pool. I will tackle more of it tomorrow.

So that gunky stuff is all over the tubes but very thin. Its like if you get it on your skin it stains. Soap and water gets it off though. I will probably flush it again a few times. There's this stuff called Irontite that you run in the system for up to 12 minutes and it supposedly removes all that gunk. I will clean everything up and then put that stuff in. Hopefully it'll clear it all up and then I will run green 50/50 (peak brand). Drive it over to AutoZone and have them check for codes. If that is my fix then I will work on my items - horse shoe intake and new exhaust manifold. I will probably put Jet Hot on the exhaust.

Hopefully all this work will do what I need.

 

So I go outside to work on getting some coolant into the system. I plugged the radiator at the bottom passengers side with its plug, put in some 50/50 mix with water. I started it and let it run a little, then noticed a leak on the plug area of the radiator. After letting it cool down, about 10 minutes I have quite a puddle on the driveway. I put a bucket under the leak and pulled the plug, out comes more brown colored water. Just when I thought it was all taken care of. I looked up Youtube on how to remove this gunky stuff and someone used Irontite. So I call the local auto stores and no one has it. Amazon has it but I havent received it yet. Hopefully this stuff will work. Also my plug is threaded and is stripped. I am not sure if its the threads that keep it from leaking or the "o" rings. On my plug there's 2 places for the rings and only one of has one. I took my handy box of "o" rings out and couldnt find anything that I liked, plus the missing threads. Off to the auto store to get a new one.