308 HDI, RHR strange engine noise.

[306Eran]

Hi there,

I have a 2011 308 Sportium HDI Auto, with the RHR motor. It has done 74,000 KM's.

I'm really not sure how to describe the issue, but when under acceleration when driving or accelerating slightly even when at speed, there is a strange rattle sound from the engine, almost like slight growl (Grrrrrr) sound. The sound last for only a second or two then disappears, it is not present throughout the rev range when driving.
The issue is that it comes and goes, it isn't a consistent sound. I have noticed the sound is usually more present between 1500-2000 RPM range.

I know my description is quite vague, I really don't know how else to describe it. All in all though the car drives perfectly fine and the sound has been present for quite a few months.

Has anybody had a similar issue or any idea as to what this sound might be.

Thanks

 

[Stuey]

Has any of the pipework been taken off the air intake/induction system? Sometimes these are tuned to be quiet and changes can cause resonances which show up at certain rev ranges particularly under load with the throttle open.

 

[Ken W]

My C5 X7 with RHR also made that sort of noise until I changed the fuel pressure regulator solenoid on the Delphi HDI pump.

Cheers Ken

 

[306Eran]

My C5 X7 with RHR also made that sort of noise until I changed the fuel pressure regulator solenoid on the Delphi HDI pump.

Cheers Ken

Thanks Ken, is there anyway to properly diagnose if it is the exact same problem. And is it a big costly job to replace?

 

[David S]

Another possibility is the alternator pulley clutch. It's an over-running design, so it turns one way but not the other. You can experience a lot of vibration from this item when it's failing or has frozen solid.

 

[306Eran]

Another possibility is the alternator pulley clutch. It's an over-running design, so it turns one way but not the other. You can experience a lot of vibration from this item when it's failing or has frozen solid.

Hi David, I'm experiencing no vibration from inside the car. I'm assuming the alternator clutch pulley is an easy visual inspection to tell if it's failed? That's the bet directly in front of the alternator correct?

I have a feeling this is not the culprit, as this noise has been present for months, wouldn't a failed alternator clutch pulley render the car undriveable?

 

[David S]

You should be able to turn the alternator only one way against the pulley. Think of it as being like a ratchet and treat it a suspect if it feels gritty or binds. Maybe, not you problem if there is no engine vibration. This is usually worst at idle and drops off as rpm increases.

That engine is known to sometimes go into a kind of surging at a light throttle, just enough to repeatedly rock your head back and forth and be annoying. It's to do with the EGR valve control and the last resort fix is a blanking plate with an 8mm hole to damp the EGR operation. Again, possibly not quite your problem, but worth being aware of.