MG MGB and MGB GT Tech Talk
was looking at this B and tried to open the rad cap,couldnt get it off but fianally did
stuck my fingure around the top ridge where the water goes in and wiped off this black looking sludge,what could that be or be a sign of?
Probably just residue off the radiator cap seal. They get slimey as they age.
You can easily flush your cooling system and get rid of most of that.
Here's how.
You'll need the garden hose, a 5 gallon bucket (or larger), and a long hose that can reach from the t'stat housing to the bucket.
Start the car and get it sort of warm. You want the thermostat open but you don't want pressure to have built up. shut down the engine.
Take the present top hose off the t'stat housing. Hook up the long hose and stick the other end into the bucket. have the garden hose with a small stream (just a little more than a trickle is all you usually need). Restart the engine. Water will start going into the bucket (you'll be surprised by how little, even at full flow). the top hose is still connected to the radiator so put the garden hose in that top hose and adjust the flow so it's about the same as that of the water coming out. Don't turn the hose on full. You'll get water all over the place than the fan will blow it in your face as well as elsewhere.
When the flow into the bucket is clear, like that of the water going it, you are finished.
Usually the 5 gallon bucket won't be full yet (the rad only holds 6-7 quarts).
thats good but trying to find out what caused it, the fact that the rad cap was almost impossible to get off has to mean something8-)