Strange Noise On Cold Startup

[cantavoidcitroen]

Hi all,

My 2010 Citroen C5 2.0 HDI has developed a strange noise which can only be heard from a cold start and I'm hoping to get a second opinion on what could be causing the noise. Last week I had the cam belt including roller/s & tensioner, water pump, auxiliary belt including tensioner and crank pulley all replaced for a couple of reasons. First off all was peace of mind but the second was because the auxiliary belt was squealing on both start up and under load, even though it had only been replaced 5000 miles before hand. Once done the squeal from the belt was gone and all has been hunky dory since.

However, last night when leaving work a few seconds after start up I could hear a consistent noise that I haven't heard before. The noise is there on idle but once throttle is applied the noise stops but comes back again when returning to idle and stays, same goes when turning the steering wheel either way. The noise can be heard when driving but only when the engine is idling or when the wheel isn't being turned. The noise does disappear after a few minutes of driving and will only return when left for a few hours.

I have a video on my phone where the noise can be heard clearly but I don't know how or if i can upload the video to the forum.

If anyone could point me in the right direction it would be very much appreciated. Thanks.

[myglaren]

You will need to upload to YouTube then post it here.

[xantia_v6]

Take a look at the belt and make sure that it has not partly slipped off one of the pulleys.

[white exec]

To confirm belt noise (if it is that sort of noise) squirt a little water on it while it's running, and the noise should change/disappear.

[picassodad]

Take it back to the repairer first as its under some sort of gaurantee, see what they say and go from there. Do this asap ad pdq, do it toady or at least phone them.

[cantavoidcitroen]

Here's the link to the video where you can hear the noise.

[myglaren]

Something wrong with that link - do you have it set to 'private' or 'public' - should be the latter.

[cantavoidcitroen]

It was set as private Should be able to view it now

[white exec]

That slightly uneven clonking sound sounds like either a loose pulley (or cushioned crank pulley breaking up?), or something heavy clonking on bodywork/subframe/chassis. Engine mount?

[cantavoidcitroen]

Would you have any idea as to why the clonking noise dissapears after a few minutes of driving?

[white exec]

Just one idea: immediately after starting, the load on the alternator is very high, and this backs off over the first few minutes of driving, while the engine is warming up.
To test this, after the noise has gone, try switching on a heavy electrical load (headlights, foglights, heated rear window, heater fan on full....) and see whether any noise returns.
Sod's law says it won't, of course.

[admiral51]

Just checked with the OP ( My Son ) and the noise itself does not appear to come from belt or roller/tensioner etc.
Removing the engine cover you can feel vibration over what i believe is the cam cover/ injectors ( too late to remove the secondary cover ).
It feels/sounds more of a popping exhaust sound and although the noise goes away when sat in the car it is still there when warmed up only not as noticeable from within the car, with the bonnet open you can hear and feel it.
Too cold for me tonight to continue investigations but does that make any sense?
Car seems to drive well, no lack of power etc, could the previous squealing belt have masked the issue ?
Or as i suspect its sods law that this is a new issue, it really does not sound/feel like a metalic sound, but on the video it does sound metalic i must admit.
To me it is more of a popping sound be resonated around the engine bay which makes me think it could be injector issues.
Will put the 2nd Devil car on the DiagBox tomorrow or saturday

[admiral51]

Just a quick update as i have driven the car today for a short distance.
I am 100% convinced i am wrong about injectors being at fault
Even when warmed up the noise is there under 1k revs, seems to disappear above 1.2k revs and yes the car drives fine, lots of grunt etc.
Having looked at the list of what has been replaced i can only point the finger at what has not been replaced, the air con compressor and the alternator.
I think Chris may be bang on the money with saying the alternator could be at fault. As in the OP there was a squeal coming from the Aux belt and would go away once the Revs were built up, hence why the lot was changed. The belt did need changing, as did the tensioner but i think they may have been masking the issue that he has now.
I think it is the alternator bearings that are making the noise, particularly as the steering pump is electrically driven not belt driven and the noise did go when the sterring wheel was moved.
Question is why would it appear to have been fine for 4 or 5 days once everything else had been replaced.
Car is going back to the garage Monday night so will not get any answers until Tuesday.

[sparksie]

Okay, I still can't access the video, but that's due to my clockwork internet connection.
I suspect you may have an alternator pulley with an overrun clutch that's failing.
You might be able to see a wobble in it, if it's very bad, but really, the best way to check it is to let an auto sparks look at it

[Filberton]

Can you localise the noise? You can get an engineer’s stethoscope or, as I do, I have a long screwdriver (about a foot long) with a wooden handle (but plastic works). Press the handle in your ear and, taking great care not to touch the tip on a moving part, touch the tip on various areas. The noise will be loudest where the noise is I.e if touching the case of the alternator is louder than touching the block etc.

My experience is that noise can echo so just looking in may lead you to suspect a wrong part but a stethoscope or probe nearly always works.

Just please take care with moving parts if you have not done this before.

Mike