Bad noise at high revs: any thoughts?
Discussion
The last two times I have been out in the Chim, the engine note at high revs (over 5,000 in this case) is quite nasty and seems to have changed. Obviously, progress is so rapid at this engine speed, I havent had a chance for a good long listen, and I dont want to annoy the neighbours by revving it to 5,500 rpm for a minute on the drive, but anyone got any ideas. It sounds like a REALLY loud, metallic screaming noise. It does sound quite cool, but cant help thinking something expensive may be wrong. (btw, I always let the oil warm up before revving hard)
I used to have a wierd noise on high revs, but this was more of a suction noise. I guess it depends how different people describe their noise.
In my case it turned out that the air intake pipe was colapsing (it is only plastic) under high revs and the related vacuum suction. This was resolved by manipulating the pipe so that the "fold point" was supported , so making it less likely to collapse. In addition to this I heat shielded the air intake pipe in case the pipe was becoming more flexible when hot, to potentially strengthen the intake pipe and to hopefully reduce the temperature of the air passing through.
Well that was the theory anyway.
However, I haven't had a problem since.
In my case it turned out that the air intake pipe was colapsing (it is only plastic) under high revs and the related vacuum suction. This was resolved by manipulating the pipe so that the "fold point" was supported , so making it less likely to collapse. In addition to this I heat shielded the air intake pipe in case the pipe was becoming more flexible when hot, to potentially strengthen the intake pipe and to hopefully reduce the temperature of the air passing through.
Well that was the theory anyway.
However, I haven't had a problem since.
Try to be positive, at least it is not drivetrain or gearbox related. Assuming the engine has not lost power, is not burning oil like a refinery or is not belching like a steam engine it may well turn out to be something peripheral. I agree with others screaming noises tend to be from pumps etc. It could be the alternator, as it was replaced with a secondhand one you may have just got unlucky and fitted one that was near the end of its life.
Good luck, and let us know what it was...
Good luck, and let us know what it was...
Ha ha, twit is a name I have had since primary school, nearly 30 years now! But I like to think I am not that dumb...
Anyway, when you revved it in neutral did you do it on your own, i.e. you in the car. Assuming you did, it could be worth repeating the exercise with the bonnet open, a mate in the car and you standing in front if it is a squeel from a pump or anything you should be able to pinpoint the area it is coming from and hopefully the potential faulty component. I have never worked on a TVR V8 but Rover V8s are really strong and when they do go they tend to make low down rumbling noises , on Landrovers they do! I suspect it is something like an alternator or even one of the belt/pulley combinations, but best get it checked.
Does it smell of oil all the time? As the car is not moving when you rev it hard you will smell more than normal anyway cos' the fumes just stay in one area as oppossed to some distance behind.... That might explain you smelling it last night for the first time.
Thats my guess!!!!!
Anyway, when you revved it in neutral did you do it on your own, i.e. you in the car. Assuming you did, it could be worth repeating the exercise with the bonnet open, a mate in the car and you standing in front if it is a squeel from a pump or anything you should be able to pinpoint the area it is coming from and hopefully the potential faulty component. I have never worked on a TVR V8 but Rover V8s are really strong and when they do go they tend to make low down rumbling noises , on Landrovers they do! I suspect it is something like an alternator or even one of the belt/pulley combinations, but best get it checked.
Does it smell of oil all the time? As the car is not moving when you rev it hard you will smell more than normal anyway cos' the fumes just stay in one area as oppossed to some distance behind.... That might explain you smelling it last night for the first time.
Thats my guess!!!!!
cheers mate, will try that this weekend. You're right about the smell. Only smelled it when revving car hard while stationary. It's going in for the once over from David Batty on Monday. Fingers crossed....
Anyway, will forgive car almost anything.
>> Edited by loudpedal on Friday 26th April 12:44
Anyway, will forgive car almost anything.
>> Edited by loudpedal on Friday 26th April 12:44
Anyway, will forgive car almost anything.
As you should!!
I am still in the 'trying to sort cash' phase of potential TVR ownership. It will happen soon! Good luck with yours, hopefully it will nothing serious. The once over won't do any harm anyway as if there are any other niggles they can be sorted!
As you should!!
I am still in the 'trying to sort cash' phase of potential TVR ownership. It will happen soon! Good luck with yours, hopefully it will nothing serious. The once over won't do any harm anyway as if there are any other niggles they can be sorted!
Just a thought. I had a similar problem with mine. Turned out that an engine block mount had corroded and split and when revved hard the engine was rising and causing the PAS pulley to grind into the swirlpot! In fact it grinded so far coolant started to leak out. Made a funny smell too!
Had it checked out by the Garage and I have bounce in my valve return springs. Apparently, this is not too deadly, but it will be worth changing the springs at a later date, say next service. I have been advised that they can be uprated at this stage. Does anyone know wht benefit this may bring? Also, the problem is apparently worsened by revving the car in neutral, and I have been advised not to do this. Now I like to give the car a few revs in neutral (only when the oil's hot tho') just to pierce the morning air with a bit of V8 growl. Is this just a juvenile thing that i should stop doing for the sake of my engine or should it be ok within reason?
quote:
Had it checked out by the Garage and I have bounce in my valve return springs. Apparently, this is not too deadly, but it will be worth changing the springs at a later date, say next service. I have been advised that they can be uprated at this stage. Does anyone know wht benefit this may bring? Also, the problem is apparently worsened by revving the car in neutral, and I have been advised not to do this. Now I like to give the car a few revs in neutral (only when the oil's hot tho') just to pierce the morning air with a bit of V8 growl. Is this just a juvenile thing that i should stop doing for the sake of my engine or should it be ok within reason?
Stranger things have happened, but this is a new one on me. I have revved engines hard enough to encounter valve bounce in the past (very briefly and it really gets your attention) and it is a potential engine killer. Even if you don't get a valve/piston interface it knocks the hell out of the cam, which isn't a strong point of the Rover V8 in the first place. Never done it on a V8 but you can get similar symptoms (loud clattery noise at high revs) when the lifters pump up. Is it possible this is what they're referring to? And they're sure it isn't just pinking or something simple like that?
Genuine valve bounce and lifters pumping up both only happen to a healthy engine at extremely high revs (for a V8, this means in excess of 5500 rpm). If you are getting these symptoms at much lower revs, either there's something seriously wrong with the valve train or a more general engine problem - either way could quite easily lead to major engine damage.
Re revving the engine in neutral, from the mechanical point of view this is really no different to revving the engine while driving except there is less ambiant noise so the noises are more obvious. If it isn't safe to rev the engine to (say) 5k stationary, it isn't safe to drive the car. All IMO.
Cheers,
Peter Humphries (and a green V8S)
Cheers Mr. Humphries, the aforementioned noise does indeed only happen at 5500rpm and over, and the neutral revving thing was explained to me in that the rise and fall in engine speed is a lot more rapid at standstill (no load on the engine), thus putting more strain on the moving parts.
Any ideas on the valve return spring upgrade thing?
Cheers
Jake
Any ideas on the valve return spring upgrade thing?
Cheers
Jake
quote:
the neutral revving thing was explained to me in that the rise and fall in engine speed is a lot more rapid at standstill (no load on the engine), thus putting more strain on the moving parts.
From the mechanical point of view, this explanation doesn't make sense. The inertial loads on the engine are identicaland the engine is producing the same torque. The only difference is this torque is spent accelerating the engine instead of the car.
Sounds like your problem is only occuring at very high revs and if so I don't see how you could possibly hit it normally - whether you're revving the engine or not. I assume you aren't sitting there bouncing it off the rev limiter!
have to echo green v8s thoughts valve bounce really does sound terminal, chimaeras have double valve springs and usually hit the rev limiter long before valve bounce territory,plus springs dont weaken suddenly, usually age and high milage.its very difficult to diagnose without hearing it, has it occured recently or over time , if recently then i would get it looked into thoughly before carrying on driving it,better safe than sorry
The car has done just over 48,000 miles and the bounce has only just started occurring. Took it to David Batty's and it was he who OK'd it. Apparently, it should be ok to drive for the time being, even into the valve bouncing rev range; I should just avoid revving it to 5500rpm in neutral. when the time comes for the next service, I should get the valve springs replaced, possibly with an upgrade. Anyone think otherwise (last thing I want is to wreck the engine)?
the rev limiter should come in at about 5800 to 6000 at 5500 you should be nowhere near valve bounce, 48k is not high for a rover v8 even in a tvr,if it is valve bounce you should avoid bouncing them it hammers the rest of the valve train, the weak links in the valve train are rockers and cam,at the end of the day its your car if you still have doubts about driving it(judging by this thread you have)try and get as many technical opinions/trained ears to advise as poss
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