During a leisurely drive at modest speeds yesterday, my 328 developed a strange noise on top of the normal engine noises. I'd describe it as resembling the noise a dog or cat makes when it scratches at a door wanting to be let out. Its frequency is about once a second or a bit quicker, and the volume rises and falls at random. I tried to see what would happen if I revved the engine, but then the engine noise masks the scratching sound so I can't hear it. At least I know that its volume does not increase with rpms. I looked in the engine bay with the engine running and could not see or smell anything out of the ordinary. Performance while the sound was happening seemed to be unaffected. All gauges read normally. Any theories?
Well, it can't be a wheel bearing, since I also hear the noise with the car idling at rest. Belt idler bearing? I don't know much about them, but I guess that's a possibility. Plastic bag? I doubt it, but the next time I pull the car out in daylight I'll see what I can see around the belts to see if there is anything visible. Thanks for the responses. Any other theories?
Check to see if the following hoses are contacting the body in the engine bay: A/C lines off of the compressor Oil cooler lines more probably the a/c lines around where the engine intake tubing contacting eachother. this causes the vibration of the engine to carry to the chassis and the intake tube. the a/c lines must be as isolated as possible to elimnate and noise. best regards and good hunting jim
Just thought that my 355 had a similar noise which turned out to be the ac belt or the alternator belt. Easy way to check is to buy some belt conditioner in a spray can and apply to belts and if noise goes away you know the solution , new belts. My noise was mainly when cold and it was a flick , flick sound just like the belt had something stuck to it that was flicking something, this was not the case though.
In Massachusetts, I'd sometimes get that kind of sound just after starting on cold, dry mornings. It didn't stay past warm-up, and there was no problems found at the service. The theory was that it was electrostatic buildup in the belts, like a Van de Graaff generator.
Remove your drive belts to see if noise is still there. Also grab your waterpump pulley and see if there is any play in the shaft. I just had the same problem with my 1986 328 GTS and found the waterpump front bearing was shot causing the problem. It gave no other indication of a problem because it was not leaking nor was it running hot. Also spin your drive belt idler pulleys and make sure they spin smoothly.
I had a slight clicking noise coming from my mondial's engine bay and found that it was my a/c belt not tight enough. The bolt to do this is on top of and behind the compressor towards the fire wall. You have to take the air intake off. Not sure about the 328 but layout should be generally the same. Mine still clicks for a few minutes until the car gets hot but not continually like before. hope this helps, Nate
This noise disappeared and was replaced by a "clattering" noise (see my other thread). Ironically, my mechanic (who's coming over tomorrow), suspects that an accessory belt, possibly the a/c compressor belt, might be at fault. You might be right, Nate!
