What is this noise??

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petef
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What is this noise??

Post by petef »

I originally posted this query on the Air Con Forum because I thought that the noise on my Xantia Activa Series 1 was coming from the air con clutch or the compressor itself. But now, after advice received there and further investigation it would appear that it is coming from the HP pump or the alternator - but which? The noise only happens when the air con is on, and coincides with the cooling fan switching on - but it's definitely not the fan bearing. It lasts a few seconds, can be stopped by revving the engine and doesn't happen when everything is warmed up. A' listening stick' - a length of metal tube and plastic pipe doesn't provide a definitive answer - the alternator and HP pump are mounted on the same support and seem to transmit the noise equally - both sounding very loud.
Has any body heard a noise like this before? Because it coincides with the cooling fan switching on and the extra load put on the alternator, I am inclined to suspect that this is the source, possibly a bearing on the way out? However, before replacing it - a tortuous job on an Activa - I would like to know my toil would not be in vain. It was suggested that I stop the cooling fan switching on to reduce the load on the alternator and see if the noise fails to appear by pulling the relevant under bonnet fuses - no's 3 and 5. However doing this doesn't stop the fan coming on! Also I have recently replaced the auxiliary drive belt - but the noise was there both before and after it's replacement, although it did stop some belt squeal.

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white exec
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Re: What is this noise??

Post by white exec »

Try leaving the cooling fans and AC alone (ie off), but switching on a really heavy electrical load, so that the alternator has to do some hard work. Suggest hested rear window, all headlights and foglights, and blower.

Does the alternator have a freewheeling pulley by any chance? These can break up (and be replaced).

How's the tension on the aux (AC, alternator, hydraulic pump) belt? Too tight or bit slack?

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petef
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Re: What is this noise??

Post by petef »

So, in the end, I bit the bullet and replaced the alternator having convinced myself that this was the source of the screeching noise. I managed to source a keenly priced, guaranteed, refurbished one and eventually completed it's fitment today. Thanks to CitroJim for the blow by blow how to do it for the Activa in an old post from way back when. Still hugely useful and without it I would have probably given up.
Unfortunately this did not cure the problem though - the screeching noise is still there when the air con is engaged on startup. So I must reluctantly confirm that the noise is definitely coming from the HP pump. However the pump otherwise works well, there are no leaks and (for an Activa) there is rapid rise of suspension on start up. I did notice a bit of end float on the pump and wonder if this might be related? Is there any adjustment or lubrication of the bearings possible (or is the latter one of the functions of the LHM being pumped) ? Or could cheap Carrefour branded LHM in the reservoir not be up to spec?
For the record the feed pipe from the reservoir was replaced some time ago with a brand new one, is still in good order and there are no air leaks.
I am loath to part with £200 for a refurbished pump but, if this becomes the case, would someone - Marc? - please confirm the correct part number for my XU10J2TE engined Activa VIN VF7**************[VIN obfuscated, can be read by forum staff], I reckon it is 4007 T9 . There are many pumps and I want to be sure I get the right one if it comes to that. But is there anything I can try first????

davoxx
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Re: What is this noise??

Post by davoxx »

Is that noise not the aux pulley? I could be remembering wrong, but mine sounded like that when under load.

oscar
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Re: What is this noise??

Post by oscar »

Could be to do with Steering wheel on wrong side! :shock: :lol:

Which type of crankshaft pulley you have?
Mine had smooth one with like a trumpet/cornet in middle which the outside part is flat on face.
Other has the three slots around outside edge they grind metal! has the three tabs catch face as raised

Mine which was month old failed melted rubber gear inside so inner and outer came together making loose on crank but when old and failing will squeal/slip.
Look down and check how wobbly! also mark across bolt/trumpet/Face with paint pen? so can see if moving under load?.

Is the spring loaded Tensioner ok? if allowing belt to slip under load often ceases as catches up/load equalises!

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white exec
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Re: What is this noise??

Post by white exec »

For your VIN, that is the correct HP Pump pt.no. - 4007 T9.

Looks as if the crankshaft pulley is one-piece solid, and not dual-mass (as some are), judging by the fact that it (0515 H6) is now NFP. Dual-mass versions tend still be be available, because they can fail. Might be worth a peep down there, though.

So far as I can see, there is no spring-loaded tensioner on the Aux belt, but there are two idler rollers:
1 - Retractor roller (fixed position)
2 - Tensioner roller (adjusts aux belt tension).
Might be worth checking out both of those as well.

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petef
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Re: What is this noise??

Post by petef »

Before going down the pump replacement route , I have ordered a new aux pulley to see if that makes a difference. The old one seems ok but, I suppose you never know when they're under load.