That's probably the first time the cooling system has had that kind of attention in who knows how many years. I would just chalk it up to a build-up that you were able to find and get rid of (Casting sand, manufacturer leftover metal bits from assembly at the factory left to stew with time, etc)I'm puzzled as to how the gross gunk in both the heater core lines and the surge tank has not managed to mix with the bulk of the radiator fluid with all of the draining, filling and driving that I've been doing? Is it possible that my water pump is not working effectively?
That brown does look like what dexcool can do when there's air getting into the cooling system.By way of an update ...
I installed my new radiator after flushing everything the best I could. I have then filled and flushed after driving a couple of times. The fluid draining from the radiator looks as I expected - clearish with green tinge. After the last drain I removed the surge tank that heavily coated in brown stuff (probably clay residue) in order to put a new one in its place. I was quite surprised when the removed surge tank puked a load of very brown gunk all over my jeans. I managed to capture some and take a photo to contrast it to the fluid that came from the radiator drain. Important to note in the attached photo that the radiator fluid in the drain pan is discoloured due to other various auto slime that was already in there. It was actually clear with a green tinge.
I'm puzzled as to how the gross gunk in both the heater core lines and the surge tank has not managed to mix with the bulk of the radiator fluid with all of the draining, filling and driving that I've been doing? Is it possible that my water pump is not working effectively? View attachment 659078
Cascade-powered automatic dishwasher cleaner works great. It is a base and will clean your internal cooling system. I've used it on friends' trucks and vans. You may have to flush several times. I'd use 1 cup of cascade to your radiator with water, not coolant. If the engine not running then buy an "OTC 6043 Blast-Vac Multipurpose Cleaning Gun" which works great.Thanks. I also think it's the clay tablets. If it's through the block I don't think that stuff is ever coming out. If it stays where it is and doesn't inhibit heat transfer I'll just carry on.
I back flushed the heater core and saw this (bear in mind I've been running green coolant for a considerable amount of time). I don't quite know what to make of it: View attachment 659064