328 GTS Rattle/Resonance

It is often caused by the A/C hoses going over the top of the fuel tank. Some people just go in there and insulate them from the bodywork and the tank with foam rubber or similar material.

 

Type of exhaust?

 

your talking about exhaust resonance right? I have 85 308 and I get the same situation. It does have the original exhaust. Been driving me crazy as I have looked at every nut and bolt as well.

 

it's the A/C

check the bolts too.

 

It's the A/C lines hitting the inside of the right rear fender. Take off the wheel well liner and place padding between the lines and bodywork. VERY common problem!

 

In my case it was the bolt securing the cambelt cover. I removed the rear wheel and the cover to have free access, torqued the bolt and everything went quite.
Ciao
Eugenio

 

Could also be the air intake resonating on whatever is near it. The location of the interference is near the side duct. Mine did this.

 

Your water pump is failing. Check the play on the bearings, I think that you will find ypur problem. I chased that resonance for a month prior to discovering the water pump.

 

Did you remove the intake when you replaced the water pump? A bearing making that kind of noise will freeze up in short order. I doubt it is the water pump.

Take a look at the intake. It gets worn away where it is contacting something else. Mine did this. It was obvious.

 

I have seen water pumps go bad right from the start. Does not hurt to double check.

 

More then likely the A/c lines are rubbing the body work...But I have seen on a rare occation the coolant pipes which pass under the center of the car through a tunnel rub together creating a strong "rumbling type noise. Normaly it has just been the insulator around the pipes, that keep them from touching together or the frame work, and has fallen apart with age. I replace it with a thin peice of inner tube, wrapped around the pipe.

 

A yard of flexible plastic pipe stuck in your ear makes a marvelous microphone for tracking down noises.

Honest

 

AC lines rubbing , mine had it also , re route slightly or foam, all fixed v easy.

 

Also rattling/noisy components:

Inner wheel arch bottom end fibrating (no support).
Louvre window door.
Exhaust cladding loose.

 

That engine goes through a harmonic vibration in the 3200-3500 range. I have traced a number of noises at this RPM range. For me to tell you exactly what it is cannot happen. I have found cam belt covers loose, metal fuel line from the pump area vibrating, intake duct and others. Just have to find what it is on your car.

Good luck, your car is normal, drive on. After you find the noise.

 

I had the same - for years - until I realized, that it began after a A/C service and was caused by the A/C lines. I rerouted them a TINY bit by simply altering the angle of the fittings on the compressor, and the noise was gone.

Best Regards from Germany

Martin

 

I agree with Lawrence, I had almost exactly the same resonance and it was caused by the air cleaner vibrating against the A/C compressor. I modified the air cleaner slightly and never heard it again. Everything is so extremely tight in that area.

Bill

 

You'ved been hosed...

 

Did any of you notice you are giving advice to someone who had a problem 10 years ago?


I suspect he has fixed it by now.

 

I didn't.
Well, the purpose of this forum is to learn.
I did.

Next lesson please

 

Oh, now that you tell us
But honestly I had the problem for almost 10 years till I was able to fix it.

Best Regards

Martin