Persistant Coolant Leak From Rear Of Engine

[Ryan 99]

I've had a slight coolant leak from the water distribution block for a long time, but the location makes it hard to see exactly where from. I've taken it apart 4 or 5 times and replaced everything - the distribution block itself, the rubber seal between it and the engine block, all the coolant pipes and hose clamps, and the metal water pipe from the back of the head. Is there some trick to sealing it that I'm missing?

[welshpug 1,657]

sure its coming from that and not a cracked block?

 

Either across the base of the water jacket, or the infamous water pump casing hole where the headbolt spacer has been forgotten.

[dcc 855]

could be a crack in the engine block, common for people to miss the spacer above the water pump. Might be a bodged repair.

[Ryan 99]

It's dry all around the water pump, and there was no headbolt damage when I rebuilt the engine a few years ago.

 

It seems to be coming from the distribution block itself, somewhere around where the three smaller hoses are connected. Do the two 11mm bolts go all the way into the water jacket and thus need sealant on them?

[Anthony 1,003]

They shouldn't do normally.

[welshpug 1,657]

All I can think of is to ensure the bolts are the correct 25mm long ones, and they have the 0.8mm washer, and the correct o-ring (metal housing used a gasket)

[Tom Fenton 1,541]

It is not an o ring, it is a square section seal.

[luggy 13]

the rubber seal between it and the engine block, all the coolant pipes and hose clamps, and the metal water pipe from the back of the head. Is there some trick to sealing it that I'm missing?

 

Had a similar issue even with a new rubber seal, sorted it by putting silicon sealant at the bottom of the seal seat, about 2-3mm high, let it cure, new seal in and reassemble. ​