Engine noise

[whaleys]

Hi Guys,

I have spoken to someone who has said to check around the manifold/exhaust for leaks (particularly around the oxygen sensor) but I thought I'd also run this past you. I've started to get a putt-putt-putting noise from the engine, or around it. It could be a dull knocking noise but it's only noticeable when idling. You can just hear it from the engine bay, but if you're not used to what the engine normally sounds like you may not hear it. It's more noticeable in the car, again just when idling, its not loud just this dull knock that is an "new" noise. It's a regular putt/knock noise around 3-4 times a second.

I've heard when there are cam or bearing problems that the engine sounds like a diesel. This isn't a cracking knock but a quiet dull knock/possibly putt.

It's always hard trying to describe a sound but hopefully you get what I mean .

It's a 2002 k-series with 36,600 on the clock.

Thanks,
Graeme

[Shug]

Can you smell more fumes?

[whaleys]

I haven't had a chance to look at it since I was told to check the exhaust. When I did look I wasn't paying attention to any smells, there wasn't anything obvious, but I'll check tonight.

It was serviced in March and I've checked the oil level and it's fine and the oil is still averagely clean.

[whaleys]

Thinking about any coincidences, this has just started after the my most recent fill up of fuel. I filled up with super unleaded from Sainsburys, have been putting in standard recently.

Added: The noise is still there when the car has warmed up.

[whaleys]

Had a look and listen last night. I dont think it's the exhaust, it sounds like its coming from the top of the engine, toward the left side (expansion tank side). It would seem like it's around the cams?

Its a standard k-series engine not VVC.

Graeme

[robin]

Does the noise change if you put the clutch down?

Cheers,
Robin

[whaleys]

Does the noise change if you put the clutch down?

No, there isn't any change. The noise is still quite quiet. I read that the noise can sometimes be caused by a loosening timing belt, if the tensioner isn't doing its job? It had a C-service 2 years ago but not sure if the tensioner was replaced. I've been using the car the last few days, its not getting any worse and there isn't a drop in performance at all.

[philthy]

the noise would come from the other side if it was the tensioner?

try maybe listening to it through a section of hose to pin point where its coming from?

[whaleys]

I think it's not the noise of the tensioner but the "slack" causing a slight timing delay. Good idea with the hose, will give it a try, hopefully the neighbours wont see me .

[robin]

By the time you're over the pax side of the engine, on an S2, non-VVC K-series you're down to valve train or exhaust manifold or spark plug.

The exhaust manifold might be ticking away due to broken gasket or loose bolt - they're a sh*t to do up on the S2 with the bendy heatshield eating the skin off your hands. You might get somebody to help you here - two old rags, fairly chunky cloth, stuff up the exhaust pipe while the engine is running - this will increase back pressure in the exhaust manifold and will accentuate any noise made by gas escape. Al

You might actually have a bit of hydraulic lifter noise - can be caused by reduced oil flow into the lifter and so it doesn't quite pump up properly. You could try a hydraulic flush additive into the oil and/or an oil change for that.

Spark plug is unlikely - if it were loose you would be losing some compression which would probably cause the odd misfire/some change in performance. If it's electrical arcing inside the plug bore, you would also get a misfire. So checking spark plugs would be my last resort.

Cheers,
Robin