Blocked cat / exhaust overheat engine and increase consumption?

[rowan194]

The whining noise in my AUIII is becoming more prominent. My father in law reckons it may be the exhaust.

Recently my trans has overheated a couple of times, and I also noticed the coolant temp was higher than normal at the time. Fluids are normal.

So I had a thought, maybe the two are related... especially since an exhaust leak developed recently in a join where I hadn't tightened the bolts enough. I had gasket cement on the join, I'm thinking the cement sealed it for a while, but eventually the backwards pressure caused the cement to fracture and subsequently leak because of the loose bolts.

So if there's blockage, the engine itself is overheating, which is then raising the temp of the coolant and overheating the trans...?

I haven't noticed any loss of power, but the engine has been drinking 10-20% more fuel than normal for months. This change happened suddenly.

Is there a way to check the cat converter? What's one of them worth?