The test makes sense but it still won't tell me if I have another issue like a water pump going bad or possibly a oil pump. To drop the oil pan is not a huge deal and could reveal a lot more. The noise is definitely coming from the front of the engine down low near the oil pump so who knows, nothing ventured, nothing gained besides the Disco is just a project truck and we have a few newer cars for daily driving that are better on fuel.
Keep you posted on the findings.

 

you do know that you have to remove the front cover to drop the oil pan. right?

 

Actually the other way around.
The oil pump pickup is attached to the front cover and you have to remove the oil pan first to expose the bolts holding it in place.

 

Wow, that is bad.
Thanks for the pictures.
I still have Dexcool in mine.
I plan to change it once a year.

My brother has a Discovery II and he has not changed the Dexcool in 5 years.
He does not drive it hardly at all.
I told him he had better get it changed to green in his case.

 

I would honestly buy a new t-stat and rad, they are not that expensive and dump that Dexcool crap because it will destroy your cooling system. I flushed the engine in both directions till it ran perfectly clear then put in the new rad and new 180*t-stat and it runs nice and cool, I strongly recommend it.