Bad Engine Noise
Discussion
Hi Guys,
On the way back from a nice blast today the car developed a nasty sound from the engine. It is a loud rattling sound that varies along with engine speed and appears to be coming from inside the engine, rather that as a result of an ancillery component. The car only has 29,000 miles on the clock and is always toped up with oil. The car got me home and didn't seem particularly down on power, but oil pressure seems a little low 30psi when running, but there is plenty of oil in the sump.
I am going to book it into the local garage early next week and just hope it isn't too serious
On the way back from a nice blast today the car developed a nasty sound from the engine. It is a loud rattling sound that varies along with engine speed and appears to be coming from inside the engine, rather that as a result of an ancillery component. The car only has 29,000 miles on the clock and is always toped up with oil. The car got me home and didn't seem particularly down on power, but oil pressure seems a little low 30psi when running, but there is plenty of oil in the sump.
I am going to book it into the local garage early next week and just hope it isn't too serious
AntonyJ said:
Yes, might have to wrangle it past the lower windscreen trim and unplug the stepper, disconnect the inlet pipe.
Dont forget to re-seal the plenum to the base.
Thanks Antony. I had a quick look in the bible and couldn't see anything on plenum removal, but guess it is fairly straight forward. One question though, what should I be re-sealing it with?Dont forget to re-seal the plenum to the base.
Cheers,
Alex
Next step would be to take the rocker covers off and check cam lift on all of the lifters. I'd recommend doing it like this:
Remove the rocker assemblies and push-rods then get a long probe on the end of the dial indicator and turn the engine over by hand to measure valve lift. Push the rods through a bit of labelled card to ensure they go back where they came from.
The reason for measuring the lift at the lifter means you're not caught out by a lifter that's not pumping up properly as the small spring inside them isn't sufficient to overcome the valve spring load.
If the lift is as it should be ( according to your cam details) then check the condition of all the rockers and push-rods, its not unknown for rockers to lose their pads or push-rods to be bent.
If these are OK then remove the lifters one by one with a magnetic probe and check they are fully pumped up, the inner piston should be solid with oil with only a tiny bit of give / squidge to them when pushed by hand.
If not then either strip and clean that lifter as its most likely bunged up or replace with new.
You could just check the lift at the rockers was the same on all inlets and the same on all exhausts but if you find differences then your're into the above
Best of luck
Matt
Remove the rocker assemblies and push-rods then get a long probe on the end of the dial indicator and turn the engine over by hand to measure valve lift. Push the rods through a bit of labelled card to ensure they go back where they came from.
The reason for measuring the lift at the lifter means you're not caught out by a lifter that's not pumping up properly as the small spring inside them isn't sufficient to overcome the valve spring load.
If the lift is as it should be ( according to your cam details) then check the condition of all the rockers and push-rods, its not unknown for rockers to lose their pads or push-rods to be bent.
If these are OK then remove the lifters one by one with a magnetic probe and check they are fully pumped up, the inner piston should be solid with oil with only a tiny bit of give / squidge to them when pushed by hand.
If not then either strip and clean that lifter as its most likely bunged up or replace with new.
You could just check the lift at the rockers was the same on all inlets and the same on all exhausts but if you find differences then your're into the above
Best of luck
Matt
The most common top end rattles (both sound very similar) are Exhaust Manifold Gasket and Rocker Pad Failure. I’ve had both and I’m presently about to re-do the manifold gasket for the second time this year.
If the rattle came on suddenly it’s more likely to be the manifold gasket that has just let go. This is more pronounced when the engine is under load.
If the rattle tends to vary in intensity as the engine warms, then to me this suggests it’s more likely to be rocker related i.e. noisy on initial start then quieting as it warms, to getting noisy again as it gets hot. If on the left bank when you remove the oil filler a tappet rattle should sound louder.
Just my opinions, hope it helps,
Simon.
If the rattle came on suddenly it’s more likely to be the manifold gasket that has just let go. This is more pronounced when the engine is under load.
If the rattle tends to vary in intensity as the engine warms, then to me this suggests it’s more likely to be rocker related i.e. noisy on initial start then quieting as it warms, to getting noisy again as it gets hot. If on the left bank when you remove the oil filler a tappet rattle should sound louder.
Just my opinions, hope it helps,
Simon.
Thanks Simon. The thing that makes me think it is either valvetrain or crank related is that the rattle varies with engine speed. As the revs come up, so does the frequency of the rattle.
To be honest I am so short of time at the moment that I have got the car booked in to V8 developments for them to take a look at it (it should be in safe hands). If they need to start striping the engine then I am going to use it as an excuse to get a Stealth cam in at the same time - every cloud should have a silver lining
To be honest I am so short of time at the moment that I have got the car booked in to V8 developments for them to take a look at it (it should be in safe hands). If they need to start striping the engine then I am going to use it as an excuse to get a Stealth cam in at the same time - every cloud should have a silver lining
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