What sounds like noisy tappets but isn't?

[SebastienClement]

My brother has an old Vauxhall Agila 1.2 as his first car.

When used for longer journeys it begins to make a noise quite like tappets that don't have any oil. It's perhaps a bit quieter though. It happens while the engine is running, and when the car is stopped.

The peculiar bit is the noise isn't in time with the engine revolutions, and does not get faster when revved. In fact as you rev it the engine sound drowns out the ticking.

Ideas?

[ikarl]

possibly something lose?
like a washer rattling around on a lose bolt?

[jjones]

could be injectors

[Mikeyplum]

Is it a fast or slow tap? Does it occur at random intervals (rather that a rythm?)

[SebastienClement]

jjones said:

could be injectors

Wouldn't that get quicker with revs though?

It's very intermittent. It'll just do it randomly and then stop again. Not other symptoms other than the noise.

[kambites]

Maybe something like the fuel pump?

If it doesn't change with engine speed it's unlikely to be anything driven directly from the engine.

[HereBeMonsters]

Alternator/aux belt rattling a pulley?

[loose cannon]

Don't these suffer from rattly chain and tensioner like the corsa's ?

[SebastienClement]

kambites said:

Maybe something like the fuel pump?

Good call.

[Crafty_]

charcoal canister purging ?

[John D.]

Crafty_ said:

charcoal canister purging ?

Clio 172/182 tend to sound tappety when hot because of this IIRC.

[SebastienClement]

Crafty_ said:

charcoal canister purging ?

Hmm. It's a noise that we've never heard before. The car is an X reg and it's been in the family since new.

It's loud enough to make you think you should pull over, if for example, you're stood at traffic lights. Can't hear it at speed though.

[BFG TERRANO]

give it an oil and filter change with good quality oil, this helps.

[SebastienClement]

BFG TERRANO said:

give it an oil and filter change with good quality oil, this helps.

It's had one just before Christmas. Made the noise prior to this.

[Chris Peacock]

Alternator bearings shot?

[SuperHangOn]

exhaust manifold gaskets can tick but tends to be when cold

[PHuzzy]

Any chance it could be a loose heatshield? I have one at the minute and sounds similar to what you've described.

[BFG TERRANO]

try using a long bar, screwdriver or socket extension. With the engine running put it against the rocker cover and the other end against your ear. Move it around various places to see where its coming from. An old trick i learned as an apprentice, be carefull not to snag it in moving belts etc.

[digger the goat]

Try pumping the brake pedal......(whist stationary)
If the sound goes away it is a vacuum problem...(plunger worn)

[aw51 121565]

If "the noise" isn't related to the engine speed, then it's not caused by the engine or its ancilliaries . Possibly, anyway, but I'd look away from the engine for now .

Perhaps it's the power steering electric pump? Or a valve somewhere in the PAS system? Wear in the steering rack? Does the noise (or its characteristics) change when steering lock is applied or released?

Could also be the fuel pump, as others have posted.

Or anything that operates at a constant speed when in use but is sometimes 'not operated'? This admittedly would rule out the fuel pump though...