water pump leaks.....is it me?

[a1rak]

From a previous earlier thread you can see that I have had trouble with sealing the water pump to engine block/sump joints. I have fitted the new 3.5mm seals very carefully cleaned and assembled the pump to block with a very small smear of silicon followed the instructions in the AJP engine build manual but when I have assembled the units and pressure test them they still leak....Am I missing something? is there a particular point in the assembly I am doing wrong. Any suggestions would be appreciated.

[caduceus]

Where is/are the leak/s coming from exactly? Any pics?
Did you offer up the metal to metal surfaces first to check mating tolerances?

[a1rak]

The leak is from the joint between the water pump and the block. There was no leak before he rebuild and apart from dismanteling the engine assembly no machining of the block or the pump was done in this area .I would have pressumed it would have been a new set of O rings and careful re-assembly but it refuses to seal.

[fatjon]

Did you notice that one of the 4 screws holding the front impeller housing on has a thinner head than the other 3? If you get that one in the wrong position the pump assembly will not sit flush to the block and will leak.

Jon

[a1rak]

hi john
i didnt strip the pump housing apart, i only took the complete assembly off. but none the less i will check it just in case it has always been wrong.