I am hearing a dat, dat, dat, dat, dat sound that sounds like a diesel engine. Someone has recommended I check the catalytic converters. Any other suggestions? My Disco is a 97 w/ 118,000 miles. It is running great, just making that annoying sound. It can only be heard with the windows down.

Criag

 

We can't even hera the noise when you put the windows down. Go crawl under the truck while the engine is running and try and pin point a little closer, where the noise is coming from, then get back to us.
Mike

 

I will give it a shot but I don't know if all 350 of me will fit under the truck.