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Engine noise sounds like bb's

4K views 25 replies 14 participants last post by  shay2nak 
#1 ·
When I'm at cruising speed and slightly lifte off the throttle I hear like a hand full of BB's thrown at my engine. Almost like a diesel engine noise Doesn't happen when I'm in the throttle. Could this be timing chain Guide broke?
 
#3 ·
Does noise change with engine speed?

Try tapping your exhaust system to see if that is source.
 
#5 ·
Check bolts in engine mounts. l had odd rattling sound and that's what it turned out to be...loose bolt in engine mount.
Same here, it was front mount that was loose. On the throttle the motor pitches and puts most of its force on the rear mount... Mine would never rattle while on the throttle but partial throttle or lift would cause it to rattle. Found one bolt missing and another loose--replaced both and added some thread locker, problem was resolved.
 
#8 ·
Pinging after lifting off? Not likely.
 
#10 ·
It doesn't sound like he is lifting all the way.
Are you completely off the throttle when it happens? If it happens with lifting the throttle slightly, maybe he can't hear it during acceleration at that higher RPM due to exhaust noise.
Maybe he hears it when he lifts slightly because the exhaust doesn't drown it out. Easy to eliminate it as a cause.
 
#9 ·
It's mostly when you just slightly lift off the throttle at higher rpm's. Say like 4000 rpms. The noise is not very loud at all. I've asked people if they can hear it and they tell me no. I guess just my ears are toned to it. Just kind of worried about hurting the motor. I do push this car up to about 7500 RPMs often. But now thinking maybe I shouldn't until I find the problem. So I purchased the car six months ago everything seems to be fine and works well other than that noise. Car has 34,000 on it. And is that really a lot of miles on that kind of motor?
 
#11 ·
OP, did you check exhaust and heat shield yet? Better that then guessing on the web.

Gently tap with a rubber or plastic mallet with car off.

Engine moves about when one is lifting and this is still my guess.
 
#13 ·
FYI for anyone suffering the same concern; I replaced both front and rear motor mounts with Innovative mounts and updated to BOE Fabrication studs. The vibration in the car is much more noticeable (obviously), but the noise that sounds like ball bearings rattling around on deceleration is gone. Fairly certain it was the rear mount so I would recommend starting there.
 
#15 ·
05 Elise with 14000 miles. Same BBs bouncing around sound coming from (it seems) behind the passenger seat area when slightly off throttle 3-4000 rpm 3rd or 4th gear.

I just installed front and rear engine mount poly inserts. All bolts/nuts were tight. BBs rattling around sound still there.

Also recently checked exhaust and heat shield connections. Banged on everything I could find. Bent heat shield slightly in a couple of suspect locations. Sound is still there.
 
#16 ·
05 Elise with 14000 miles. Same BBs bouncing around sound coming from (it seems) behind the passenger seat area when slightly off throttle 3-4000 rpm 3rd or 4th gear.



I just installed front and rear engine mount poly inserts. All bolts/nuts were tight. BBs rattling around sound still there.



Also recently checked exhaust and heat shield connections. Banged on everything I could find. Bent heat shield slightly in a couple of suspect locations. Sound is still there.

This sound was discovered a while back. The cables for the transmission rattle because they have some give. People have put weights on them and such and it gets rid of it.
 
#21 ·
I had an annoying rattle at certain RPMs that I found was a loose center brake light above the rear window.
 
#22 ·
Easy test...

First thing to do is take off your under tray and diffuser. Check for anything obviously loose and make sure the heat shield is not coming into contact anywhere. Then drive the car with the under tray and diffuser off. I had a similar situation, turned out it was related to an under tray rattle. You'll know right away if the sound goes away. In my case I thought it could be engine related and it wasn't. Added some nylon washers and adjusted the heat shield and problem solved.

Good luck.
 
#23 ·
I got some leather washers from McMaster-Carr.

When dealing with large panels of almost any material, tighten center first, then alternate each side as you work towards ends.
 
#25 · (Edited)
Ok those are the words I was looking for. I too have this noise and never could describe it. This said my issue the best.

"
Same BBs bouncing around sound coming from (it seems) behind the passenger seat area.
"

For me, I have it with throttle open. As soon as I hit 4-5 k, its like a lot of BBs bouncing around in my SC.

I always thought it was the SC... I had my exhaust looked at as it does sound heat shield related but no luck. What the heck is this?


Now I also have the issue of rattle that happens went I let off the throttle but I learned long a go, it is that linkage issue where holding the shifter to one side or the other makes it go away.
 
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