Engine Rattling Sound

TravL350

TravL350

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Hi all - I am just getting acquainted with my Coupe I bought in December. It has a rattle that I have not been able to identify.

The sound is sort of like a metal can with nails in it. It happens under steady acceleration in the 2,000 RPM to 4,000 RPM range, and also sometimes under deceleration while in gear. It doesn't increase or decrease with engine RPM, and does not happen at idle. It is also a more random rattle and not a repetitive rhythm like a knocking or pinging, and doesn't sound like its coming from the exhaust. Any ideas?

Thanks in advance,
Travis L
 
rattling

Check your belt tension.

Alternator or bushings in the mount.( stick a big screwdriver in the mount and pry.

Timing chain or tensioner.

Water pump/ bearings.

Fan, etc. Does it wiggle?

Go back over the bolts to the above accessories and the power steeing pump.
 
In addition to what has been said...Where do you hear it coming from?

You mention might not be the exhaust; but do you suspect the noise is not in the engine compartment? Also, you hear it under accel and sometimes decel...if coming from underneath next to you while driving could be a release bearing.

Can it be heard by someone outside the car (i.e.: someone next to you, or someone on the street as you go by)? to help isolate the where is it coming from.

Jon
 
61porsche said:
Check your belt tension.

Alternator or bushings in the mount.( stick a big screwdriver in the mount and pry.

Timing chain or tensioner.

Water pump/ bearings.

Fan, etc. Does it wiggle?

Go back over the bolts to the above accessories and the power steeing pump.
Click to expand...


In addition to the above under hood suggestions: since it may be related to vehicle speed, you have the drive line to examine, including: u-joints, drive shaft coupling, center support bearing, cv-joints, wheel bearings, and lug nuts/bolts. Then there is exhaust hangers, or an exhaust with loose internal baffling.

You don't happen to have those bolt on dynamic balancers attached to your wheels? The ones with pellets? Not to make light of this, but is it possible you have a tool or tree branch or other unwanted dead weight stuck in a wheel well or near any moving parts? Because you are just getting acquainted with car, have you examined for the loose items under the seats or in the well where the wiper assembly is located? You may actually find the previous owner's can of spare change or misplaced tambourine.

hth
 
Last edited:
Thanks guys, I will be checking things over in those specific areas tomorrow.

I definitely have at least narrowed it down to the engine bay, sorry looking back now that was not clear in my original post. Plus I have vacuumed up about $3 in loose change and yet no tambourines to speak of!

The belt & fan feel tight but haven't checked bolts on the mentioned accessories. I'll do some more digging tomorrow morning. Thanks again,

-Travis
 
I remember having a similar sounding noise sometimes (I thought it sounded like a light chain dragging under the car) and it turned out to be a screw-cap on the front section of the driveshaft. It wasn't screwed on, so it "jangled" around, making the noise. The part itself was pretty close to the center support bearing. Once I screwed it on, the noise went away.
 
Just thinking...Before you drive it a lot to investigate what and where, consider checking the timing chain & tensioner that has been listed earlier...I would not want a failure in there. Xatlas's comment made me remember a loose timing chain (it was bad/weak tensioner) noise.

Also, on the water pump that was also listed earlier, is there any drips in the weep hole?

Jon
 
I had an annoying rattle on my Bav and it turned out to be that one of the heat shields bolted to the top of the exhaust manifold was loose. It would rattle at certain rpm ranges, and not at an idle.
 
I had a similar rattle. Check the 6 bolts that attach the downpipes to the front of the center muffler. They can appear tight but these bolts stretch over time, even new bolts have to be extremely tight or the flanges rattle and can be very loud.
 
Mike Goble "I had an annoying rattle on my Bav and it turned out to be that one of the heat shields bolted to the top of the exhaust manifold was loose. It would rattle at certain rpm ranges, and not at an idle."

+1
I was about to make the same suggestion.
Also check the airbox to assure the nut/bolts to the carbs under the cover are securing the airbox proper from vibrating and rattling--and be sure the airbox lid is secured by the 6 hold down clips.
 
JhwShark said:
Just thinking...Before you drive it a lot to investigate what and where, consider checking the timing chain & tensioner that has been listed earlier...I would not want a failure in there. Xatlas's comment made me remember a loose timing chain (it was bad/weak tensioner) noise.

Also, on the water pump that was also listed earlier, is there any drips in the weep hole?

Jon
Click to expand...

Or, even worse, the timing chain guide rails. Ugh, those are such a pain to deal with.
 
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