Death rattle?

I really shouldn't have rattled the cage of the Gods of Reliability in an earlier post...

Out for a drive and after pulling out from a junction and nailing it, an ominous rattle suddenly started up. I pulled over, assuming something had just come loose in the engine bay but nothing obvious. I slowly drove home - the rattle sounds like the same noise you get on cold starting, before oil gets round the engine. Only seems to happen over 2000 rpm and on gentle acceleration - hard acceleration doesn't seem to be a problem, weirdly.

A post on a forum brought forward ominous warnings of terminal bearing failure caused by petrol in my oil because I'm running too rich. OK, yes, I am running rich but not excessively, I don't think, and even if it was, could it cause that much damage in just 3k miles?

While looking for the problem, I also noticed that I was leaking coolant from the temp sensor in the top of the thermostat. I took it out and found that the plastic adaptor the sensor plugs into has cracked! Wonderful...ordered a couple from Emerald (1 for a spare).

I've been thinking about getting a wideband lambda sensor for a while now; ordered one and will see how that goes (specifically, will I be able to get the bung out of the exhaust). I've specifically ordered a Spartan2 because Richard L has one and he posts lots of very useful detail about it and I may need all the help I can get.

Next step is an oil change to look for metal particles, which will help tell me if there is any physical engine damage. I would like to also change the coolant - it's a horrible rusty colour - but I've got enough to do.

While I'm wiring in the lamdba sensor, I've also got a couple of other jobs I could do at the same time:

1. Get the water washer working.
2. Move the main beam switch away from the headlight beam switch, so I don't mistakenly turn off ALL my lights when trying to get main beam on.
3. Fix my USB charger port on the aux panel - seems to have stopped working (I've checked the fuses).

Not happy times....