Got a 6 year old 306 (60k miles) and recently i noticed a "knocking" noise coming from the front of the car when accelerating hard and generally when the engine is under load - it's quite loud going up a steep hill for example. There's no noise when idle or if I rev the engine without the clutch engaged. Any ideas?
It could be the exhaust manifold. John
Is it diesel or petrol?
My diesel (HDI) does exactly this .... on going up hill it makes a knocking sound (not very loud but noticable) or when accerating hard (i.e. in forth gear accellerating whilst joining a motorway) When the engine gets to exactly 3000rpm on mine the noise stops completly
Sorry, I forgot to mention...It's petrol. Actually the noise is really noticeable when driving close to something that reflects sound (like another car, tunnel walls, hill side and so on) - most of the time it's just a faint knocking metal-on-metal noise. It sounds really really bad when the sound is reflected back though, like two bits of metal hitting/scraping against each other. I noticed the same kind of noise when I'm about to move off in first gear but don't really give it enough gas (almost stalling it).
The clutch doesn't feel like it's going. Having said that, I've had the car for 3 years and have yet to change it...To be honest I'm kinda scared it's the gearbox. Could it be that the gearbox might be leaking oil? How can I check? (I don't have a driveway so it's impossible to tell if I've got a leak by just looking at the ground).
From what you say it doesnt sound like a gearbox prob, I was just saying that cos from what u say it seems odd u can hear it in a straight line. When you say scraping noise i sort of thought of brakes and warped discs or drum.
When you hear the noise can u feel anything through your pedals or steering wheel? Normally when a CV joint goes you can feel it when you accelerate round corners, although not all the time but most of the time u can.
when you change gear does the noise get slower until you have to change gear again or does it just get faster and faster?
sorry for all the questions but its kinda hard to diagnose this without hearing it. Most knocking noises are either when turning a corner or something quite big has gone in the engine. I wouldnt think exhaust banging off the car because when that vibrates it tends to get bad at about 2500 to 3000 revs and then because of the vibration it tends to go away and the whole car makes a humming noise!
scott
I had a problem with mine where the car would produce a bloody awful loud rattling noise when the engine was under load. It did it when you accelerated anything more than gently and was more pronounced going uphill. As with you it also was fine when just revving the engine.
I put it into a garage because past very simple things I know nothing about cars and they said it was to do with the exhaust. They said something like 2 of the exhausts sections weren't quite totally aligned up and that this bit vibrating was the cause of the noise. As I said, I'm no expert and might not have remember what they said properly so this might not be quite right, but it was definitely exhaust related and it only cost me an hour's labour to diagnose and fix.
Gavin
It won't be the clutch or gearbox.
If its a regular knock with every turn of the engine which increases with engine revs, and gets worse under load its likely to be a big end, which is bad news.
If its a higher pitch metalic clicking rather than a knock, the tappets need adjusting, but you would normally hear this even on tick-over.
Should really get big-end trouble with such a low mileage unless its been driven hard or without oil.
Looks like I'll have to take it to a garage :( Prob is i'll be in france for a while and don't speak french LOL
Anyway, got a few other people to give me their opinion on what it sounds like (what kinda noise it is) and none of them could agree :) I got various descriptions from "harsh, scarping noise", "tick/scrape", "knock/scrape" to "faint knocking". All I can say is that it's rare when it's just me in the car (basically, only when going uphill and accelerating hard) but it happens a lot more with other people in the car (never heard it in first gear, but it does it in all others). If it's the big end, is it likely the engine's burning oil? Because I checked the levels and it doesn't appear to be the case. Cheers guys.
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