worf928

Right. That's what's weird, what has my attention, and what makes this an 'interesting' problem. As Doc Brown wrote: something's not right.

Powder coating of the water bridge can make it hard to get hoses under pressure to seal. But, that hose - if it's the one I'm thinking of - is rarely the problem. It's usually the big hoses that go to the radiator.

All the other likely culprits: old hose, 'finger trouble', wrong hose clamp seem to have been ruled out. It's just ridiculously unlikely that both Greg and another shop, as a group, would over-look or mess-up these obvious things.

I wonder, also, if this new hose has simply been mis-manufactured and is too big. It seems - from reading - as if the replacement of that specific hose is what started all this. If I recall correctly the ID of the hose is different at either end. I have to wonder if perhaps this fact was over-looked when this batch of hoses was made? You could certainly install the hose 'backward' but that seems highly unlikely.

Mrmerlin

was the cooling system ever contaminated with oil?.
If so then any rubber in the cooling system will absorb this oil and then become soft and slippery any hoses that appear to be slippery should be removed from service/.

NOTE if the system was contaminated with oil,
then running some water and tide for a an hour should break the oil deposits from the system.
Then replace the hoses,
NOTE the hose may look perfect on the outside,
its the oil thats has been absorbed that you cant see.

All 3 outlets on the WB have some type of protrusion to hold the hose,

NOTE if the outlets are coated in powder coating then this will cause the hose to slide once the pressure is built up and the hose will slide off.

Remedy get some 220 grit paper and abrade all 3 of the outlets,
clean the inner areas of the hoses after you have washed them with simple green and hot water, inspect the inner hose areas for protrusion damage.

GregBBRD

OK. That makes more sense. If you look closely at the casting at the crossover for that hose, you will see that the casting gets smaller at the open end...so that the casting would come out of the mold. Porsche installed a couple of brass "nubs" to retain the hose....they are probably covered with powder coat and doing very little to retain the hose.

I never powder coat water crossovers, figuring that hose retainment is going to be an issue on that super slick surface, so I've not got many suggestions on how to fix this, other than removing the powder coating.

New hoses are soft and supple...crushing easy when tightening. Old hoses get hard and brittle, but do not deflect as much, when tightening....thus absorbing more clamping force. I try to not randomly change hoses, because of this...but have little choice when the hose is bulged.