Contour Enthusiasts Group Archives Forums General Troubleshooting Help - Timing chain woes. I think

My 2.5 mondeo's going to be the death of me.
First I've got this Catalytic convertor problem
producing the cars inability to rev past 4,000
accompanied by a screaming sound from the engine
(See my previous entry)
Today I took an improvement in the British weather to look under the bonnet . At idle the car emits a rattling sound from the top of rear bank's timing chain cover .It's quite noticable compared with the front bank, which is very quiet.
I have also noticed a recent oil leak from some sort of bolt arrangement on the rear bank above the idle tensioner (which is fairly new itself) .
My question is :- Is the the timing chain tensioner broken. It occurred to me that if the tensioner was not working as the revs rose the cam timing might change causing loss of performance Or is it simply a tired old chain . The car has about 81,000 miles
Is it a DIY job with the engine still in .

What year is the car?

The car is 1996 model .

Since posting I've had the Cat replaced and the cars fine now performance wise.Infact it's the quickest it's ever been and I've owned it 3 years.

Still rattles though . My mechanic said sell it if it gets louder.

New guides,chains,tensioners and if bad gears,camshafts...!!!!!!!