Bmw Z4 35is 2013 Overheating (Continuation)

[Crater]

a little update on my Z4 that had two overheating incidents second one it spat coolant. bought a block tester, came back negative for any warps cracks or anything of the sort on the block. Bought an OBD2 Reader, a lot of error codes mostly relating to my dying battery but i did get two codes relating to the water pump, 2E81 & 2E82 (Electrical coolant pump, speed deviation & Electric coolant pump, cutoff). IF anyone is familiar with those codes and what to do after finding those any suggestions are greatly appreciated, We also pressure tested the system, didn't find a lot about what the pressure should be but i believe our family friend mechanic had ran it between 22-30 psi which are the numbers i found online. after the pressure test was over we found a puddle on the drivers side so we took a look under the hood and the mechanic told me it was a leak where the rubber hose crimps onto the radiator, he said its worth buying a new radiator instead of recrimping it. any second opinions on that would also be super helpful. also thinking about buying the radiator and doing the work myself.

a couple of my main concerns and questions are.
what do i make out of those codes? did they pop up because of the leak or do i need a new waterpump and thermostat.
if i replace anything in my cooling system, should i do a full coolant flush and if i need to do so is a coolant flush hard and trivial.
When replacing my radiator myself, do i need to do anything besides removing the old one and putting the new one in.
also where is the best place to look for torque specifications and all that when doing work on my vehicle. Thanks again for any help, new to the community and the car, i'm only 21 so I don't have much experience with vehicles especially anything foreign, trying to soak in as much as i can and make these posts that could possibly help other people in the future!

[Crater]

also sorry for the hard read guys, not exactly the best writer but i'm working on it.

[B21]

Well it superficially looks like your ‘friend’ has f***ed up your cooling system…

The error codes are the standard codes for a failing electric coolant pump..

The standard solution is to replace the coolant pump and the associated thermostat..on the grounds that incrementally whilst replacing the pump it’s best to replace the thermostat as they often fail ..

The pressure test of the coolant system normally is not required as the coolant pump failure causes the coolant to barf out ..

The pressure test is way in excess of what is required AFAIK…

[matsmith749]

Oh my very gosh.

Increasing the pressure on the cooling system without knowing the safe / correct levels can only end one way - something will spring a leak.

So that might be another thing to add to you list to get fixed.

Waterpump & thermostat will get you started - the rest may (or may not) be an issue. It's not a simple job for someone that is new to working on cars, I would recommend taking it so someone who is familiar with these engines & has all the gear etc. It's a big stripdown job.

By all means attempt it, but from your messages so far this would come under the category of not DIY, but BIY (Break It Yourself).

& change the failing battery - 101 miscellaneous issue will go away.