rattling sound under the hood 1996 Mercury

I wonder if you guys can help me. I have a 1996 Mercury Tracer which I just bought a week ago. It runs great but there is a rattling sound under the hood.....it doesn`t sound like it`s coming from the engine but more like behind it. The rattling gets worse when I accelerate. I was told that getting an oil change and then using an additive would help with the rattling.....well, I did just that and it didn`t go away. I had checked the oil before the oil change and it was black. Any ideas what it could be? Have the exhaust system and especially the catalytic converter checked. Should I have the engine checked as well? A guy told me that it might be a bad valve, but here is the thing.....the engine is rebuilt with 36,000 miles on it. The rattling sound is metallic in nature....at least that`s what it sounds like to me. So at first I thought it might be the engine but I tried to listening to different parts and it is loudest directly behind the engine. I checked the coolant in the radiator and there seems to be some oily deposits right inside but the coolant itself is green. Is that any help? Thanks If you haven’t had the car checked out since you bought it would be a good idea to do so. Not just because of this noise but a good once over can identify any potential future problems or maintenance needs. The residue in the cooling system may be left over from the prior engine problems but you should ask that it be checked out also.

Does the rattle happen at idle or if you rev the engine in neutral or only when driving?

If the noise sounds like it’s coming from behind the engine it may very well be from the exhaust system. The cat. converters on these and other Fords are known for coming apart internally and making noises.

Let us know what you find out. The rattling happens when the car is idling and gets louder when accelerating. I will have it checked out as soon as posible......thanks. I had a guy check it last night and he thinks it might be the water pump bearings going bad or the timing belt is loose. He is doing a diagnostic this morning just to make sure. But he doesn`t think it`s the exhaust. Ok, keep us updated.. Hello sudden_stars!

If it's an automatic transmission, I'd have the torque converter/flywheel bolts checked. I've seen flywheel bolts work loose and cause a rattle such as you describe.

In th Lord, Tommy