Is my 3.0 toast?

[audiophool]

So, 2004 X5 with 3.0 and 280,000km on the clock.

Recent problems with the cooling system including exploding expansion tank which also tore the neck off the radiator. Cooling system issues may or may not be related to a failed electric pusher fan, but not sure.

Extended diagnostic cycle has included a cold compresion test (obviously can't do it warm with the cooling system in pieces):

1: 165
2: 160
3: 160
4: 105 (yes, one hundred and five )
5: 165
6: 175

Cylinders other than 4 came up to about 120 on the first stroke, then a 10 or so per additional stroke until maximum reading - about 8 strokes - pretty normal, right? Cylinder 4 came up to 40 on the first stroke (ugh) then up by 10 per stroke to 105. Repeated back-to-back tests on 4 showed higher and higher maximum readings, likely as the oil was pumping up around the rings: 120/130/140/150 with about 8-9 strokes each time. I didn't try with added oil

Spark plug 4 came out wet. Can't tell if it's oil or coolant.

So I thought maybe I was dealing with a blown head gasket but that wouldn't give better compression readings on subsequent tries. At least I don't think so.

Today I borrowed a cylinder leakdown tester and now I'm really depressed. I did tests at 80psi in since that's where my compressor trips to recharge:

1: 80/77 - no leaks heard

2: 80/68 - air leakage at oil cap

3: 80/40 - air leakage at oil cap and in cylinder 4

4: 80/45 - slight air leakage at oil cap and large leakage at cylinder 6

5: 80/37 - slight air leakage at cylinder 4

6: 80/77 - no leaks heard

At no point could I hear any air coming out the cooling system at thermostat housing.

Any ideas what I'm dealing with here? I'm thinking wherever I hear air from other cylinders it may be leaking intake valves. At no point did I hear air out the exhaust.

I'm thinking of getting a cheap used radiator and putting it back together and selling it...