Loud rattling 4.3... not valve shims
Discussion
My 4.3 manual has starting emitting a very distinct rattle over the last hundred miles or so and I’m a little stumped...... however I suspect some sort of exhaust/heat shield??
- doesn’t do it at all when cold, only when fully warm
-usually at exactly 2.5k revs when stationary or on overrun, seems to be the resonant frequency
- it’s extremely metallic and high frequency, sounds like an old football rattle or metal rattlesnake! Almost like a creak.
-no fading in and out, the rattle is simply on or off
-when the car’s parked for 10 mins or so, upon starting and driving off its much worse for 30 seconds or so at low speeds then back to just at 2.5k revs
- the cats came off at service last year, valve
Clearance were also sorted then
-engines running very sweetly indeed, 90% sure it’s not engine
-exhaust valves seem to be working fine, I have a 3 way switch and can open or close no problem
Has anybody else experienced similar?
- doesn’t do it at all when cold, only when fully warm
-usually at exactly 2.5k revs when stationary or on overrun, seems to be the resonant frequency
- it’s extremely metallic and high frequency, sounds like an old football rattle or metal rattlesnake! Almost like a creak.
-no fading in and out, the rattle is simply on or off
-when the car’s parked for 10 mins or so, upon starting and driving off its much worse for 30 seconds or so at low speeds then back to just at 2.5k revs
- the cats came off at service last year, valve
Clearance were also sorted then
-engines running very sweetly indeed, 90% sure it’s not engine
-exhaust valves seem to be working fine, I have a 3 way switch and can open or close no problem
Has anybody else experienced similar?
Edited by Krhuangbin on Thursday 30th May 18:58
Not me, but from the way you describe the symptoms I’d say your first thought of some resonance in part of the exhaust system is likely to be near the mark.
As you know, any localised resonance can result in high peak amplitude vibration which can produce the noise, or it can be as a result of some sort of clash between whatever it is that’s vibrating and something else, which can also explain the thermally driven side effect.
I’d get the car up on ramps, or better a proper lift and get someone underneath listening to home in on the suspect area.
Best of luck and don’t forget to write up when you’ve found it.
As you know, any localised resonance can result in high peak amplitude vibration which can produce the noise, or it can be as a result of some sort of clash between whatever it is that’s vibrating and something else, which can also explain the thermally driven side effect.
I’d get the car up on ramps, or better a proper lift and get someone underneath listening to home in on the suspect area.
Best of luck and don’t forget to write up when you’ve found it.
Calinours said:
Not me, but from the way you describe the symptoms I’d say your first thought of some resonance in part of the exhaust system is likely to be near the mark.
As you know, any localised resonance can result in high peak amplitude vibration which can produce the noise, or it can be as a result of some sort of clash between whatever it is that’s vibrating and something else, which can also explain the thermally driven side effect.
I’d get the car up on ramps, or better a proper lift and get someone underneath listening to home in on the suspect area.
Best of luck and don’t forget to write up when you’ve found it.
Just by way of an update (and a further plea for any ideas from anyone As you know, any localised resonance can result in high peak amplitude vibration which can produce the noise, or it can be as a result of some sort of clash between whatever it is that’s vibrating and something else, which can also explain the thermally driven side effect.
I’d get the car up on ramps, or better a proper lift and get someone underneath listening to home in on the suspect area.
Best of luck and don’t forget to write up when you’ve found it.
) I had the car serviced recently and the rattle was misdiagnosed as an exhaust valve.I suspected it may have been a valve that was worn, and the inspection they did revealed they were and were noisy. They lock-wired the valves in open position for me to stop any resonance...... but the rattle persists when up to temperature and is getting worse i' d say. It's really intrusive.
I have attached a Youtube vid link i've uploaded in which the noise can be very well heard.
https://youtube.com/shorts/S-WWW6uMZ7s?feature=sha...
To reiterate:
It's not present at all when cold
Seems (as can be heard) to resonate at 2k-ish revs
Is a lot worse when the car is warm, then left for 10 mins or so, then started again., before settling again.
It from somewhere under car - NOT engine - engine is perfectly sweet, just serviced, new belt, valves done last year etc. Noise nowhere near engine
In the video, you can hear the rattling slightly at idle, then a LOT when revving.
Happens the same at standstill or moving, at same revs.
If anyone has any ideas i'd be very grateful
Calinours said:
I’d get the car up on ramps, or better a proper lift and get someone underneath listening to home in on the suspect area.
Best of luck and don’t forget to write up when you’ve found it.
TAs he said, that's the way to go.Best of luck and don’t forget to write up when you’ve found it.
It's a 2 person job (one in car, one unterneath) maybe a 3rd to ensure communication.
Pit or Lift.
Such rattling noises can be quite missleading when you hear their reflection from a garage wall.
Could be a bolt from the heat shields or one of the clamps.
BTW, sounds like poor performance from your workshop not beiing able to locate it...
TR-Spider said:
TAs he said, that's the way to go.
It's a 2 person job (one in car, one unterneath) maybe a 3rd to ensure communication.
Pit or Lift.
Such rattling noises can be quite missleading when you hear their reflection from a garage wall.
Could be a bolt from the heat shields or one of the clamps.
BTW, sounds like poor performance from your workshop not beiing able to locate it...
Indeed, was a little frustrated they said it was valves... which are now locked in place and not switchable! I will get under with some wire cutters...It's a 2 person job (one in car, one unterneath) maybe a 3rd to ensure communication.
Pit or Lift.
Such rattling noises can be quite missleading when you hear their reflection from a garage wall.
Could be a bolt from the heat shields or one of the clamps.
BTW, sounds like poor performance from your workshop not beiing able to locate it...
However for the rattle, is that what that sounds like then in the posted video.... exhaust shield or clamp, or bolts from either?
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