I had a small leak around the top of the engine and found some evidence of coolant

under the connector which fits onto the bottom of the head tank but was not sure

if the leak was there or from the tank seam so replaced the tank and 'repaired' the fitting.

I found a 3D pic of these fittings online and the seal did not look like an 'o' ring however

when I got the seal out it was just an 'o' ring.

The size was 24mm id x3mm

There were no leaks around the connector after a test drive.

I did not have the exact size so drove to a friend's house who had one the right size.

I gave him a bottle of wine and a box of mince pies for the ring and I think he got a good deal!

So did I!

 

Sorry the size of the 'O' ring was 24mm id X 3.5mm