Well not strictly my car but Mrs Noc's 75. Yesterday I thought I'd replace the thermostat and O ring as it was leaking coolant. Not the quickest of jobs, and once finished refilled the coolant and let the car warm up on idle. Lo and behold after a few minutes the coolant pipe started dripping as pressure built up in the system.
Stripped it all back out last night and this morning got hold of a genuine LR O ring and compared the size to the viton O ring I had fitted. The viton one was slightly undersize, so that explained the leak.
Fitted the LR one and all is now well. Just to be on the safe side I got the old GhettoTech cold pressure tester out and checked the system was coolant tight before fitting the engine mount and other gubbins back on.
