Maybe I shouldn't care about this noise (Xantia)

rmunns · Unread post by **rmunns** » 12 Jan 2011, 16:11

You will remember I've posted a query about a droning noise from my 90Hdi Xantia which no-one has been able to pin down. In fact, I've asked several times.

Symptoms: a steady-pitch noise (does not vary with engine speed and is also present when stationary, so not related to wheel bearings etc). This noise is just like a fan.

I have several times checked the rad. fans and they are definitely not running when the noise is present. The noise comes on while driving, but it is really only audible when ticking over (at lights, for example).

Today, in exasperation, when I completed my journey I turned off ignition and then immediately turned it on again. Engine did not fire up, but noise was there, for about 5 seconds before it cut off.

So I am now happy that the noise is not engine-related, but it would still be nice to know what it is.....................................

Unread post by **CitroJim** » 12 Jan 2011, 16:13

I've heard a vaguely similar noise on an HDi that was caused by an air leak in the fuel filter housing. The air leak made a noise not unlike you describe. It would occur too when your noise does.

Try a new housing...

HDI · Unread post by **HDI** » 12 Jan 2011, 16:16

Could it be a noisy lift pump ?

Unread post by **RichardW** » 12 Jan 2011, 16:39

I've previously postulated that it is the fuel filter, but that was dismissed. However, the fact that it comes back on after the ignition is turned on for the exact time that the LP pump runs does rather tend to lend credence to the idea. I had a similar noise on mine before I had to change the fuel filter complete as it was leaking.

Unread post by **CitroJim** » 12 Jan 2011, 16:51

RichardW wrote:However, the fact that it comes back on after the ignition is turned on for the exact time that the LP pump runs does rather tend to lend credence to the idea.

Absolutely, that was the clincher for me, especially after hearing it on another HDi under the exact same circumstance. It's a funny old noise and indeed can be described as fan-like...

falling-out-with-my-car · 12 Jan 2011, 17:10

sounds very much like the cambelt tensioner spring worn out to me this gives off a dronning sound at idle and once you drive off it stops as the cambelt tensioner pulls against it.

if you can locate the spring and press on it hard with two fingers whilst the engine is idling you may find that the dronning noise stops, remove your pressing action and it may well start dronning again. esspecially if you rev the throttle and let the engine continue to idle.

edit ( appolagies didnt see the bit about engine not running and noise still occuring).
it might be worth having the tank filter out and giving it a good clean.
regards Nigel.

JohnD · Unread post by **JohnD** » 12 Jan 2011, 18:17

falling-out-with-my-car wrote: like the cambelt tensioner spring .

Is there one?

Unread post by **CitroJim** » 12 Jan 2011, 18:21

JohnD wrote:
falling-out-with-my-car wrote: like the cambelt tensioner spring .
Is there one?

Nope. It's an eccentric roller. The axillary belt has a spring-loaded tensioner though...

Neither of these items can make a noise if the engine is stopped...

rmunns · Unread post by **rmunns** » 12 Jan 2011, 22:56

Thanks, all. Particularly to you, RichardW. I will change the filter / canister.

It's not that I didn't believe you, Richard, it's more that I'm loathe to fiddle with things unless its absolutely certain that's where the problem is. Nothing's simple nowadays and it's so easy to get into more difficulties when attempting some jobs.

falling-out-with-my-car · 12 Jan 2011, 23:31

CitroJim wrote:
JohnD wrote:
falling-out-with-my-car wrote: like the cambelt tensioner spring .
Is there one?
Nope. It's an eccentric roller. The axillary belt has a spring-loaded tensioner though...

Neither of these items can make a noise if the engine is stopped...

appolagies Jim I did mean the aux belt tensioner spring but as you say a bit difficult to see that rattling with the engine stopped the first part of the description above does kind of hint at his though. do the Hdi xantias have a lift pump then because the non-hdi's dont.

Unread post by **DHallworth** » 13 Jan 2011, 01:38

My 406 does this.

It's a strange noise which I put down to the fuel filter. I've bought one a couple of weeks ago but haven't got round to changing it yet.

If I get time I'll try it in the morning before I head to work.

David.

Unread post by **RichardW** » 13 Jan 2011, 07:54

Changing the fuel filter is not too bad - but it is a messy horrible job. Take care with the fuel lines as they are a bit stiff and can be broken. I removed the filter whole, but actually it would be better to proceed as follows:

Undo the drain plug - there should be a hose fitted - if not fit one!
Release the two pipes on the lid (press in the coloured clip, then the pipe should slide off - it might need a gentle lever with a screwdriver)
Wait a good few minutes for some of the diesel to drain off
Rmove the top of the filter (unscrew with 22mm spanner) and the element
Mop out as much diesel as you can
Now proceed to remove the remaining pipes - you may need to pop the filter off its bracket to get the bottom ones off - there's room to get around the back and operate the clip - check the new filter to see how the clip works!
Refit is reverse of removal

Turn the ignition on 4 or 5 times, leaving it till the LP pump cuts out to prime the filter before trying to start it - you will hear the air gurgling back into the tank.

Note that this may not totally cure the noise - you may need a new LP pump for that. There is a bi metallic strip in the bottom of the filter that directs the fuel to the heater in the thermostat housing when cold. What seems to happen is that this goes a bit baggy over time, and then vibrates sometimes when the pump is running. Changing the pump sometimes stops it (which suggests that a certain flow instability may not be helping), but the final cure always seems to be a new filter unit.

I have certainly not noticed the noise (I would describe it as a low hum, rather like a fridge running) since fitting the new filter unit.