What is this in radiator

I have a 1999 Plymouth Grand Voyager SE and the radiator is all gunked up with some kind of rust looking stuff. I have attached a pic. Believe it or not the radiator is only about a year old. The old one was the same way. The van does not overheat but the heat takes forever to get hot and sometimes it is just luke warm. Can someone recommend some kind of home remedy flush because the shelf products do not work. Does the engine need flushed? I have never added anything like a leak stopper or anything like that. But I have used regular tap water in it. What kind I do? I have a feeling that this will cause me problems soon.
http://img208.imageshack.us/img208/203/img0024dx.jpg

That's about the worst corrosion I've seen. It appears your thermostat has come apart and the return spring has lodged in the radiator cap opening. Change the thermostat, back flush the cooling system and refill with the correct type of coolant and a 50/50 mix of coolant and distilled water. Considering how badly that's gunked up you'll have to flush it several times to get it clean. Even then you may have to have a shop do it. Check with a radiator shop to see what type flush agent to use.

Thanks for the reply. That is not part of the thermostat. That is part of the radiator. That is how it is made. I have tried flushing the radiator with water and it does not seem to help much. I just need some kind of high power flush method.

Nice pic, also see Similar thread AF www.automotiveforums.com/vbulletin/showthread.php?t=1083343 (http://www.automotiveforums.com/vbulletin/showthread.php?t=1083343)

The water pump impeller is probably the source of cancer, it doesn't push coolant through the coolant system.
1) Add a Peak/Prestone T-flush kit to your coolant system.
2) Replace bad water pump, and thermostat
3) Isolate the heater core from the coolant system and do a back flush on heater core.
4) Squeeze all rubber heater hose's, and rubber coolant hoses during flush, it helps to brake up the rust residue in hoses during the flush.
5) Do a coolant flush on the radiator + block
6) Connect the heater core back to the coolant system.
7) Do another coolant flush on the whole coolant system.
8) Use Prestone extended life with a 30/70 mix of distilled water/coolant for extra protection against rust..

I haven't seen many radiators worse than that! That looks like no antifreeze or an extremely high mineral content water used in a system thats been leaking awhile and added to constantly. The radiator will have to be "rodded out" by a radiator shop or replaced. The use of 50/50 antifreeze or antifreeze diluted to 50/50 with distilled water needs to be used. The engine and heater core should be totally flushed and hoses replaced as well. I'd replace the thermostat and radiator cap too. In the future you may have water pump problems unless you choose to replace it now. Inspect the engine block plugs as well.

Thanks for the help guys. I just recently maybe a month ago replaced some hoses near the firewall to the heater core and I thought I might as well flush it now and I did. I did both ways. Some dirty water(rust color) came out and then it was clear after that. I ran it thru 2 or 3 minutes and it seemed to be fine(no rust water)after that. Is there anything at all I could put in it for a little while that will dissolve that junk? If the water pump impeller was at fault wouldn`t it be overheating? There is no sign of any leakage anywhere. Awhile back it seemed to be losing water but no sign of leaking anywhere but that stopped and it seems to be staying full now. There is no sign of oil in the water or vise versa.

I found a good video with a bad impeller, see http://www.youtube.com/watch?v=fjpzTcpdNTE

The trick is to get most of the cancer out, so you can extend the life of car.The more contaminated parts you remove the better results.Using a 30/70 mix will give a better rust protection, you really don't want a freeze to go bad too.

With todays seals, bearings, and serpentine belt technology it seems like impellers go bad 1st, because of neglected coolant services.

If she's not over heating or leaking, it could be air pockets in the coolant system or a bad/stuck coolant control valve.

Suspect-
Bad radiator cap, bad coolant reservoir tank, bad coolant control valve, or any shortage of coolant.

Use a garden hose with a little water pressure to force out any air pockets in coolant system.

"The van does not overheat but the heat takes forever to get hot and sometimes it is just luke warm."
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This rust/mineral deposit crap is throughout your cooling system, not just in the radiator. The engine block must be scaled up pretty thick also. You're not getting heat because it's acting like an insulator as well as a restriction in the heater core, blocking coolant flow and heat transfer. Imagine what its doing to your engine! Theres no quickie, home remedy fix for this.