OK so just went through the truck did:
Headgaskets, valley pan gasket, plenum, exhaust etc gaskets, new exhaust manifold and y-pipe, rebuilt front drive shaft, sealed a tranny crack in housing, thermostat, diff fluid, transfer case fluid, transmission fluid and filter, did the cdl linkage,have sti wires and denso 5305 plugs going in point is I have done alot in 3 weeks since purchase so I'm a bit too much invested to quit.

So the old hose (radiator upper) bleed screw twisted in half so I replaced the upper hose assembly, well driving along the 5 north headed home with my 4 year old it blew steam all over I pulled over a AP and popped hood.
The bleed screw was in half and no threads on it the threads in the hose are perfect and not marked or disfigired at all.
When i tightened it it felt like it stripped and got weird which I find hard to believe bit I barely tightened it originally but I had no issues in 3 days and 300 miles.


So here's the questions:

1) if there was alot of pressure in the system like what a air pocket does it would have escaped out of the reservoir and not the bleed screw? Yes/no

2) has anyone else had a defevtive screw right off the bat?

3) has anyone had a bleed screw blow out or is it most likely a defective screw?

 

Pressure in the system overall is under 20 PSI, the vent rating for the coolant cap. However, that usually only comes into play with very hot coolant. The water pump spec says 2.64 gallons per minute at 1000 rpm at 10 psi.

Normally if there is an air bubble it makes a water gushing noise under the dash, as coolant is always running in heater core (even in summer), if coolant is full.

Hoses could get rock hard from steam in coolant (cranked block) or a restricted sludge filled radiator (which would be ahead of the coolant cap).

Flow chart for coolant and some Dexcool sludge below.

New brass bleeder screw available from BMW dealers as posted on this site. Sounds like yours was made out of maragarine...

 

It was the hose came from world pac and the screw was soft, I'll head over to BMW in the morning and see if they have a brass on hand.
Radiator is clean and no build up in any lines tank etc even the overflow has no residual stuck to the sides.
No exhaust or gas smell in coolant at all.

It did overheat on frwy the gauge quit working then kicked on again truck ran fine no surging or weird idle issues when i stopped and it still purred perfectly when when i Jerry rigged it to drive it off the exit.

 

see https://landroverforums.com/forum/di...e2/#post293217 for BMW part number and info

 

I'm off to Carlsbad BMW in the am for it thanks. It actually mushed compared to my old bleed screw,
Thanks for the help.

Am I correct in thinking that the reservoir over flow will take the hit of pressure in the system and the screw was just a fluke.

 

Yes, if the radiator is not clogged. Quite the cave you have nearby, shows what can happen with calcium and water....