The radiator cap on my BJ8 has a rubber seal as is common. It was installed and purchased many years ago from one of the usual suspects. The radiator shop man alerted me that the rubber had stretched and grown to where it actually blocks the overflow tube. There would be no way for the water to get out if it overheated under pressure even though the cap valve opened. He said he has seen radiators blow apart because of this. The overflow is close to the top in a Healey. It doesn't take much to block it. My rubber had grown about half an inch larger then the outer diameter of the valve portion of the cap.
I remember some time ago that some vendors were providing caps with too much rubber on them. It never occurred to me that rubber in a good cap could grow to an unsafe size, but was told it is not that uncommon due to the pressure.
The fix is simple - just trim the rubber back with a blade to where it is less than the outer diameter of the valve part of the cap.
Also you may want to check the headlight wires where they cross over the vertical shrouds on either side of the radiator. The sheet metal is a V at the cross point and is sharp on one edge (the other is folded over). I found the wire chaffed. A neat chafe protector is to take a 2 in piece of clear 1/4 in. plastic tubing, slit the tubing lengthwise and slip it over the sheet metal edge. It is a natural clamp but a little Goop or silicon sealant will help hold it.
Safety related aging wear points might be a good subject for the Wiki. The fan rivets and the right rear brake hose are two more.
I remember some time ago that some vendors were providing caps with too much rubber on them. It never occurred to me that rubber in a good cap could grow to an unsafe size, but was told it is not that uncommon due to the pressure.
The fix is simple - just trim the rubber back with a blade to where it is less than the outer diameter of the valve part of the cap.
Also you may want to check the headlight wires where they cross over the vertical shrouds on either side of the radiator. The sheet metal is a V at the cross point and is sharp on one edge (the other is folded over). I found the wire chaffed. A neat chafe protector is to take a 2 in piece of clear 1/4 in. plastic tubing, slit the tubing lengthwise and slip it over the sheet metal edge. It is a natural clamp but a little Goop or silicon sealant will help hold it.
Safety related aging wear points might be a good subject for the Wiki. The fan rivets and the right rear brake hose are two more.