noisy xantia

suzie · Post by **suzie** » 04 Sep 2006, 18:37

hello everyone.the car's been going fine but today as i pulled in at the shops it started making a knocking noise from the engine,also it's idling slightly rough altho it still drives ok.my husband checked the oil and the level's ok,so to be on the safe side he changed the oil and filter anyway,but the noise is still there.any ideas??

h2ocooler · Post by **h2ocooler** » 04 Sep 2006, 19:03

Mmmm What sort of "knocking" noise is it? if its a deep heavy knock on acceleration could be big ends, if its more like a mettalic light knock could be the cam or followers.
TBH without hearing it very hard to say though

jeremy · Post by **jeremy** » 04 Sep 2006, 19:25

I wonder - start with something simple and cheap - like an air leak. If you have a Bosch injection pump cracked leakoff pipes will let air into the circuit which produced irregular running - and leads to smoke, difficult starting . . .

Engines with Roto-diesel's just leak and smell if the leakoff pipes are defective.

Other air leaks will cause similar problems - but the leakoff pipes can fail suddenly - I had a 1 year old end cap rupture on our ZX 1.9D with a Roto-diesel pump - and noticed it from the smell.

How old is the Xantia? Do you know what injection pump it has?

suzie · Post by **suzie** » 04 Sep 2006, 19:52

thanks to both of you.don't think it's cam or big ends(hope not!)if you take the revs up to about 1400 it smooths out a bit and goes a bit quieter.you may have something jeremy,we replaced the leak off pipes about 9 months ago because of poor starting and all was well till now,but just recently it has been reluctant to start.my husband says the noise seems to be coming from the bosch pump.is this possible?thanks

h2ocooler · Post by **h2ocooler** » 04 Sep 2006, 20:52

Air leak would not cause a knock, How loud is the knock? could be something to do with the timing belt or tensioner if its aroung the pump.
I think if the pump was knocking that badly it would be running baldy all through the rev range if it ran at all.
Get Hubby to put a very long handled screwdriver to his ear and probe around the enigine with it, when you get to where the knock is you will hear it throught the screwdriver.

suzie · Post by **suzie** » 04 Sep 2006, 22:11

hi guys,my husband replaced the leak off pipes tonite,but it's made no difference.strangely enough the knock's only there at idle,if you increase the revs to 1200 or above the knock goes and it runs quite smoothly.any ideas?

Post by **Peter.N.** » 04 Sep 2006, 22:21

If its a loud 'diesel' type knock, it could be a faulty or sticking injector. If its sticking, a quick thrash up the motorway might cure it. But if its something else it might make it worse. What we really need is a recording of the noise!

pikecrazy · Post by **pikecrazy** » 05 Sep 2006, 06:41

suzie wrote:if you take the revs up to about 1400 it smooths out a bit and goes a bit quieter.

Could be the crankshaft pulley

pete@co.uk · Post by **pete@co.uk** » 05 Sep 2006, 09:22

Hi Suzie

How old is the xantia and has it got aircon? and is it turbo diesel? im thinking it could be the auxilliary belt tensioner. if thats playing up the noise will go when the engine revs up if you do have this type take a look at the tensioner pully, and see if its jumping around when the engine is idling.

Pete....................

suzie · Post by **suzie** » 05 Sep 2006, 10:00

thanks for the pointers.it's a '94 turbo diesel with aircon.my husband's just out checking the pulleys and then we're just going to take it for a drive and see what happens.i'll let you know.thanks

jeremy · Post by **jeremy** » 05 Sep 2006, 10:11

Some Citroen engines have a 2 part crankshaft pulley - with the 2 parts being bonded by rubber. These were introduced on the BX 16 valve and so its possible that your TD may have one. Its apparent which you have when looking at the pulley - as a solid one looks just that - solid.

What happens is that the 2 parts come unbonded - and the outer (which carries the belt) moves in relation to the inner.

As the water pump is driven by the cambelt you can of course eliminate all auxilliary problems (alternator bearings, air con compressor, idler and tensioner and noisy belts) by removing the belt and seeing if there is any difference.

I think bad running or air can produce excessive noise - as after a misfire caused by insufficient fuel (due to air) there will be a bit of extra unburnt fuel in the cylinder - and next time it ignites it burns as well - so amongst normal explosions you get one large one - which produces a knock. I would expect smoke as well.

f00lzz · Post by **f00lzz** » 05 Sep 2006, 16:57

Could a faulty auto advance/retard be causing a 'diesel knock'??

Clogzz · Post by **Clogzz** » 06 Sep 2006, 13:15

Not a faulty automatic ignition timing advance/retard, because I hope that diesels still have self-ignition from the high compression.

Heard of variable cam timing, but don’t know about that.

AndersDK · Post by **AndersDK** » 06 Sep 2006, 23:14

Its about time the noise is located - not just "from the engine compartment".

Start by removing the drive belt - the belt that drives the alternator and aircon compressor.
Then testdrive the engine to listen for any change in the noise.
If noise gone - then either the generator or the aircon compressor is at fault.

IMPORTANT : if noise does NOT disappear but continues when drivebelt is removed - then book the car ASAP at your garage as something serious is likely to be the problem.
Could be a faulty waterpump which is prone to kill the engine - by snapping the cambelt.

f00lzz · Post by **f00lzz** » 17 Sep 2006, 20:33

Clogzz wrote:Not a faulty automatic ignition timing advance/retard, because I hope that diesels still have self-ignition from the high compression.
Heard of variable cam timing, but don’t know about that.

Isn't there an electromagnetic advance arrangement on a Bosch pump??