Citroen C5 1.6 HDi - rattle exhaust blowing under load

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Thu 27 Jan 2011 16:40
Citroen C5 1.6 HDi - rattle exhaust blowing under load - Phil1581

Once my 3 year C5 1.6 HDi is at working temperature a rattle develops under load and the exhaust blows.

At tickover there is no gas leakage from the exhaust. The rattle seems to come from the bulkead area drivers side.

The Citroen garage are baffled.

Any ideas?.

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Thu 27 Jan 2011 17:51
Citroen C5 1.6 HDi - rattle exhaust blowing under load - unthrottled

Of course there's no leakage at idle-there's no pressure and very little heat! There are a lot of interfaces in a diesel exhaust near the engine. There's a turbo, a particulate filter, an oxidation catalyst, not to mention flexible bends. Any one of these could be leaking under load. Get them to put it on a rolling road and look harder-lazy b*****s! Theyre baffled because they haven't looked very hard.

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Fri 28 Jan 2011 18:47
Citroen C5 1.6 HDi - rattle exhaust blowing under load - Phil1581

Gosh - thanks - what if they haven't got a rolling road? I have a maintenance contract with the Citroen garage and they seem to be walking away from this problem which they denied while the car was in warranty. What are my rights?

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Fri 28 Jan 2011 22:30
Citroen C5 1.6 HDi - rattle exhaust blowing under load - unthrottled
I don't know what your contract is so i have no idea as to your rights. Don't worry, diesel exhaust doesn't have much carbon monoxide in it so you won't be asphixiated-and I doubt it's doing any mechanical harm-It's just not much fun on a 3 year old car. You could try restricting the exhaust outlet with a rag to build a bit of back pressure and get an assistant to listen for any leaking. Not the best approximation of road load but better than nothing. I don't understand their reluctance to help-it shouldn't be difficult or expensive to sort out!
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Fri 28 Jan 2011 22:58
Citroen C5 1.6 HDi - rattle exhaust blowing under load - Phil1581

Thanks. I think their reluctance is to due to their avoiding difficult to diagnose (without a rolling road) but not serious faults in the warranty period.

Tried the rag up the exhaust trick but no leakage detectable. I am sure the engine needs to be under load for the rattle and leakage to appear.

I am taking the car in next week and after your feedback I feel much more confident about how to proceed. If the maintenance contract doesn't help I'll consider living with the problem while I take the matter up the management tree at the dealer.

Thanks once more - do you want me to post the outcome?

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Fri 28 Jan 2011 23:07
Citroen C5 1.6 HDi - rattle exhaust blowing under load - unthrottled
Yes please-the more hard data the better. Nothing more frustrating than finding a thread relevant to your problem only to find that the 'last page' is missing.

The garage mightn't need a rolling road. It may be possible to put the car on a ramp, and run it in fast idle while someone stands underneath. I sometimes think that some garages just want to retrieve error codes and replace parts. There are horror stories of dealerships advising customers to replace broken turbos only for thecustomer to find the problem wasn't the turbo at all, but the actuating mechanism.

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Thu 3 Feb 2011 16:07
Citroen C5 1.6 HDi - rattle exhaust blowing under load - Phil1581

The Citroen garage have traced the rattle and found that the air conditioning pipes were rattling against the bulkhead at 1500 rpm under load. They have fitted plastic ties to hold the pipes in position and that has apparently done the trick.

They have made a very significantly reduced charge for labour which seems reasonable to me.

The mechanic does not agree that the exhaust is blowing. I think it is but could it be a normal noise now that the engine has covered 30k?

I will now run the car as is until the next service in December.

Your prompt advice was very much appreciated, thanks again.

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Thu 3 Feb 2011 18:42
Citroen C5 1.6 HDi - rattle exhaust blowing under load - unthrottled

The joys of crowded engine bays! Thanks for posting the result. I think the mechanic's analysis is fair. If it's hard to find, it can't be serious-like I said diesel exhaust contains so little carbon monoxide, there's no health risk. Might it be that you're hearing a bit of turbo whistle?

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