DDF still tapping after camshaft upgrade

[Ethelred]

DDF has always had noisy cam followers - the unmistakable tapping sound that comes and goes, almost musical in it's own way.

Tom fitted cam and followers , new timing chain.
Rocker shafts were badly worn so he swapped them for a less worn pair.
Oil pressure is good with the uprated pump fitted but there is still a noise when the engine is hot.

He removed the sump to investigate further and found that the oil pickup was filthy - he's cleaned all this up and called it a day because one of the exhaust studs snapped.

If the engine still has a top end rattle that comes and goes, what could be the problem?

All of the below is now new in this car.

camshaft viper hurricane DW262
cam followers AZ794-16
cam sprocket chain kit AZ770
oil pump high volume kit AZ844
inlet manifold gasket CX7590
end seals CX2684 x2
water pump gasket CX1104
timing cover gasket CX2144

 

[christopher storey]

You do not mention camshaft bearings. Although total failure , as opposed to minor wear, of these is unusual, it is certainly not impossible , and can reach a point where the camshaft wobbles up and down in the bearings ( probably not more than 1/2 a thou, say, but sufficient to produce noise ) . It would be strange for this to be intermittent, however, unless the oil feed to the bearings was impaired

Edit : another , nasty, thought has occurred to me. On many 3500 engines, if your replacement cam is higher lift than the original , it is necessary to machine the valve spring seats to provide additional length for the spring under full compression . Without this, the coils can reach full compression before the valve is fully open , and this can be both noisy and very bad for the whole of the valve train , with broken rockers being frequently the result

 

[Ethelred]

You do not mention camshaft bearings. Although total failure , as opposed to minor wear, of these is unusual, it is certainly not impossible , and can reach a point where the camshaft wobbles up and down in the bearings ( probably not more than 1/2 a thou, say, but sufficient to produce noise ) . It would be strange for this to be intermittent, however, unless the oil feed to the bearings was impaired

Edit : another , nasty, thought has occurred to me. On many 3500 engines, if your replacement cam is higher lift than the original , it is necessary to machine the valve spring seats to provide additional length for the spring under full compression . Without this, the coils can reach full compression before the valve is fully open , and this can be both noisy and very bad for the whole of the valve train , with broken rockers being frequently the result

Thanks. If your nasty thought was on the money, wouldn't it make a bad noise all the time? From what Tom said when he rang me with the update, it is fine when cool and sounds like it is from somewhere around cyls 5&7, which sounds like its old tricks to me.

 

[harveyp6]

sounds like it is from somewhere around cyls 5&7, which sounds like its old tricks to me.

Run it with the rocker covers off and slip a feeler strip between each rocker and valve stem until it goes quiet. If it's just one, when you find out which it is you'll narrow down where you need to look by a factor of 16.

 

[Ethelred]

sounds like it is from somewhere around cyls 5&7, which sounds like its old tricks to me.

Run it with the rocker covers off and slip a feeler strip between each rocker and valve stem until it goes quiet. If it's just one, when you find out which it is you'll narrow down where you need to look by a factor of 16.

Thanks Harvey.

 

[rockdemon]

swapping a push rod on a noisey one can fix it... did Tom reuse the old pushrods?

 

[roverp5Bcoupe]

Did Tom check the lifters preload? It isn't mentioned in the earlier workshop manuals but could cause problems. This method also will find if some of the pushrods are too short.

Peter

 

[roverp5Bcoupe]

You do not mention camshaft bearings. Although total failure , as opposed to minor wear, of these is unusual, it is certainly not impossible , and can reach a point where the camshaft wobbles up and down in the bearings ( probably not more than 1/2 a thou, say, but sufficient to produce noise ) . It would be strange for this to be intermittent, however, unless the oil feed to the bearings was impaired

Edit : another , nasty, thought has occurred to me. On many 3500 engines, if your replacement cam is higher lift than the original , it is necessary to machine the valve spring seats to provide additional length for the spring under full compression . Without this, the coils can reach full compression before the valve is fully open , and this can be both noisy and very bad for the whole of the valve train , with broken rockers being frequently the result

I don't believe worn camshaft bearings cause wobbling and this noise. This because the valve springs will always push the camshaft downwards and therefore avoid wobbling. If the oil pressure is good on a warm engine, the camshaft bearings should be not to bad. For the same reason,(valve spring force), poor rocker shafts don't always mean loss of oil pressure and noise. You will see that most wear on the rocker shafts is on the top side of the shaft
I overhauled 2 RV8 engines and replaced the camshaft bearings but without some special tools, it is not easy.

Peter

 

[Quagmire]

Are the exhaust manifolds sealing correctly to the heads? When leaking they can make a tapping-ish noise.

 

[testrider]

Are the exhaust manifolds sealing correctly to the heads? When leaking they can make a tapping-ish noise.

I've come across that before too, but I doubt Chris's mechanic would have fallen foul of that one.

 

[Ethelred]

Are the exhaust manifolds sealing correctly to the heads? When leaking they can make a tapping-ish noise.

I've come across that before too, but I doubt Chris's mechanic would have fallen foul of that one.

I'd read on this forum that exhaust manifolds and put it to him hopefully as the fault.

No, it's not that - Tom extinguished that hope when he first heard the noise with his own ears.

 

[Quagmire]

Are the exhaust manifolds sealing correctly to the heads? When leaking they can make a tapping-ish noise.

I've come across that before too, but I doubt Chris's mechanic would have fallen foul of that one.

I'd read on this forum that exhaust manifolds and put it to him hopefully as the fault.

No, it's not that - Tom extinguished that hope when he first heard the noise with his own ears.

Ah bum!

Are the rockers and shafts genuine Rover/LR ones or aftermarket? I had some aftermarket ones once that the tolerances on were terrible! They made a right racket so I ended up fitting a used genuine set from a scrapper engine that were much quieter even though they had done some mileage.

 

[SydneyRoverP6B]

roverp5Bcoupe wrote,...

If the oil pressure is good on a warm engine, the camshaft bearings should be not to bad.

Hi Peter,

Maybe, maybe not. Using my Rover's original engine as an example, after 203,000 Miles (327,000km), oil pressure was still quite good, 15 to 20psi hot idle, 30 to 35psi around 2500 to 3000rpm, and yet the camshaft bearings were totally worn. The front bearing has no lining left at all, only the steel backing remained.

Ron.

 

[symes]

With Hurricane cam you shouldnt need any machining done ---but why use standard lifters---seems odd--you would be better using the Rhoads lifters
I would check your valve springs as they are not brilliant as standard--I have seen heads were springs have been different lengths--wierd problem I know--Check the free lengths

 

[Ethelred]

Thanks for the replies. I am in Cumbria but I spoke to Tom on the phone.

He's reassembled everything and it seems the car is now quiet unless the engine warms up as if it has been in traffic for half an hour. He doesn't think the rattle is emanating from the camshaft but he won't know for sure unless he strips the engine down.

I will see how it behaves and if I can put up with it or not. If it is something that gets worse with warmth, this will rapidly get worse as we approach spring in the northern hemisphere - she was much noiser in November than frosty January.

The engine is a rare and desirable high compression version with the lip seal so I'd like to get it right - it was quick enough with the badly worn parts.

 

[colnerov]

Hi, IIRC knocking when warm could be little end knock, removing the ign lead lessens
the load and eases the knock. Obviously not a permanent cure, but an indicator.

Colin

 

[symes]

In my experience--worn rockers and clogged oil filter in sump means one thing and one thing only==engine rebuild==the rover v8 having hydraulic lifters made owners lazy in regards services so quite a few v8s I had to deal with have all had one thing in common=not looked after =worn out cams on 7 and 8 and shot ends and thats just for starters!! one I had -when rocker cover removed-so much deposits that the valve springs were clogged you could,nt see valve stem !

 

[Ethelred]

I enjoy reading the replies.
Some are valid and from first hand experience of old engines. Others are derived from the reading of tarot cards .

I've just been to Lake View to swap cars - as Tom warned me, a camshaft swap has only stopped one of the rattles in Daffodil's engine - there's still an intermittent rattle that several experienced mechanics at Lake View have now listened to over the last week and are none the wiser - no one can say for sure where the residual noise is coming from.

The engine will have to be stripped down to find out where the problem lies - in the meantime Tom has done an excellent job with the camshaft upgrade - as predicted the car is much stronger at motorway revs and the engine is much smoother and quieter notwithstanding the 'incomplete success'.

I'm used to Rovers with good oil pressure but Daffodil's oil pressure is in a class of its own - the gauge is now near 60psi on the motorway - it wasn't far off this before the work.

 

[SydneyRoverP6B]

ethelred wrote,...

but Daffodil's oil pressure is in a class of its own - the gauge is now near 60psi on the motorway - it wasn't far off this before the work.

Like all things in life, sufficient is fine, but too much does not make it better, indeed in many cases, too much makes it worse.

In relation to an oil pressure of 60psi at 60 or 70mph, then unless the sender is at fault and thus reading much too high, there is a problem. Oil pressure of that nature places considerable load upon the skew gears, so it won't take very long before they are worn sufficiently to result in engine failure.

What type of oil pressure transmitter is the engine fitted with? Is it an aftermarket make where the top section is a cylinder of black plastic? If so, then you can be almost certain that the gauge is reading incorrectly, and that the correct pressure is actually nothing like that.

Ron.

 

[symes]

ethelred wrote,...

but Daffodil's oil pressure is in a class of its own - the gauge is now near 60psi on the motorway - it wasn't far off this before the work.

Like all things in life, sufficient is fine, but too much does not make it better, indeed in many cases, too much makes it worse.

In relation to an oil pressure of 60psi at 60 or 70mph, then unless the sender is at fault and thus reading much too high, there is a problem. Oil pressure of that nature places considerable load upon the skew gears, so it won't take very long before they are worn sufficiently to result in engine failure.

What type of oil pressure transmitter is the engine fitted with? Is it an aftermarket make where the top section is a cylinder of black plastic? If so, then you can be almost certain that the gauge is reading incorrectly, and that the correct pressure is actually nothing like that.

Ron.

Completely agree and also oil volume is more important than pressure- so my dad informed me years ago