Coolant Color

Hey guys have yet another cooling question. A couple of weeks ago I installed a new radiator, hoses, t stat coolant and a month or 2 ago I replaced the water pump. Yesterday I drove it around town And the temp got really high. So I parked it and it cooled off. This morning I checked the coolant and it looked rusty. The man who owned it before me was preety old and he really didn't drive it much and for that matter it doesn't look like he ever changed the coolant. When I first got it It looked like rusty mud with some water in it. What do you think it is from. I started haveing the overheating issue after I changed my intake manifold. I took it to a mechanic and he told me the radiator was extremely clogged. So after changing it It ran great for a while but now I almost have the same problem. My temp gauge Looks like its a bit bouncy. Any ideas Could there be soo much crap in the motor that its re clogging the radiator? thanks in advace. O and the t stat i used is a 180 degre mr gasket.

I'm gonna flush it tommorow. I just drove it around the block and it got super hot. I don't think the thermo was opening. I opened the hood and felt the upper hose. I could sqeeze it with out much effort. It was hot but it wasn't firm . Another question. If I remove the water plugs on the water jackets do i need to run the car or can i just use a hose in the radiator. I've never had the heads off and there weren't any tabs on my gaskets. I'm using prestone radiator fluid. There might also be crap in the radiator or motor for that part. When it runs hot the volts are lower than normal which would make me think there is more drag on the waterpump. What I don't understand is that it was running fine and now its doing the same crap. I tested the thermo before I installed it and it was working.

well I think that I found the culprit of this rust problem. I removed the coolant recovery tank and the was about 1/2 pound of greenish rusty mud. I went up about an inch from the bottom. I cleaned it all out and ran a coolant flush. On the directions of the coolant flush the directions say to run the car with this coolant flush and water for 4 to 8 hours of regular driving. I did this friday and i already notice a difference. Tommorow I'm gonna take out the coolant flush and run water in it as directed to do in the insturctions. than I can refill it with coolant. Thanks for the help. I will post any updats.