How do I stop tappet noise?

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highlandstag
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How do I stop tappet noise?

Post by highlandstag » Fri Jul 06, 2018 7:33 pm

I have recently bought a rover V8 powered Stag. I have a problem with a noisy tappet which sounds like a resonance (not ticking) that comes and goes mainly between 2000-3000rpm. The engine is old and tired. The previous owner replaced the tappets without success. However, he did find that using fully synthetic oil the noise disappeared. I am a firm believer in 20w-50 mineral oil with zddp, changed every 2-3k. Also, the crankcase was breathing excessively so I decided to change the oil back. Unfortunately, the tappet resonance has returned.

My question is: Does anyone have experience of this and how was it fixed?

The engine most definitely needs a rebuild. However, for reasons I dont want to go into now, I dont want to rebuild/replace it.

The engine details are:

1974 Rover P6 3500s
3528cc 9.25:1cr
Weber 38DGMS on modified original manifold
Tubular manifolds + standard stainless Stag exhaust
SD1 timing / ignition

Internally original (except tappets)
Unkown mileage (min 85k, probably not more than 180k)

Good points: lovely idle, plenty of torque and power, smooth
Bad points: crankcase breathing (improved with mineral oil), brown/black inside, cam worn

Current usage: mostly gentle criusing, occasional overtaking, rare blasts (does my age show?)



Quagmire
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Re: How do I stop tappet noise?

Post by Quagmire » Sat Jul 07, 2018 10:21 am

I always thought tappets and cam should be changed together, If the previous owner changed the tappets without also replacing the cam they may unfortunately have swapped one issue for another.

Whats the oil pressure like?
1974 Rover 3500s
1984 3.5 90
1959 2.25 series 2

DaveEFI
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Re: How do I stop tappet noise?

Post by DaveEFI » Sat Jul 07, 2018 10:28 am

If the cam is worn - as is said - it is silly just to change the tappets. But I have had a noisy tappet and changed just it. Cam OK. I found it by using a feeler gauge between valve and rocker with the engine idling. The old tappet still had a flat face where it runs on the cam - if it were dished, I'm not sure I'd have tried it.

I'd have though on a Stag with an RV8, you could change the cam without removing the engine?
Dave
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JP.
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Re: How do I stop tappet noise?

Post by JP. » Sat Jul 07, 2018 3:19 pm

Its not the tappets, you have probably some worn rockers. Easy to check. Remove them from the bar and look inside for their wear pattern.
'73 Ford Capri. 3.5 RV8, Magnacharger 110 Supercharger, Merlin F85 Heads, Water/Methanol Injected
'73 Ford F250, 6.7ltr V8
Building a GT40 mk2

highlandstag
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Re: How do I stop tappet noise?

Post by highlandstag » Sat Jul 07, 2018 6:57 pm

Hi, Thanks for the replies. The reason the cam was not changed is that the engine needs to come out - with the gearbox and overdrive - after jacking up the back - using high lift crane to clear the top panel - etc etc - I've seen the photos of it going in in 1983 and thats where it's stayed :-) I will check the rockers - It didn't occur to me they might the culprits.

Why would synthetic oil make a difference? Would moving back to synthetic in this age/condition engine be its downfall or is it too far gone to matter?

Thanks in advance, Chris

DaveEFI
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Re: How do I stop tappet noise?

Post by DaveEFI » Sun Jul 08, 2018 8:27 am

My brother has Stag but with the original engine. I thought after removing the rad and grille, there was quite a large opening to the front. Not possible to raise or lower the engine if the cam fouls the edge of that? The cam can tilt quite a long way once forward of its bearings.
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GDCobra
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Re: How do I stop tappet noise?

Post by GDCobra » Sun Jul 08, 2018 8:52 am

Can't you get the engine out without the 'box? I can do it on my Cobra and while it's not easy it is possible to unbolt the bell housing.

highlandstag
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Re: How do I stop tappet noise?

Post by highlandstag » Wed Jul 11, 2018 5:54 pm

I definitely cannot lower the engine. It can be raised a little, but not nearly enough. However, it looks like it might be possible to lower the gearbox and tilt the engine up on its mounts. If this is possible, I dont see why the gearbox could not be removed making removal of the engine significantly easier. Anyway, apart from the rockers, there doesnt seem to be a quick solution. If its not them I'll leave further work for the winter. Thanks very much for all your help. Cheers, Chris

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Re: How do I stop tappet noise?

Post by DaveEFI » Wed Jul 11, 2018 5:58 pm

Just for reference what would the cam foul on if attempting to change it engine in?
Dave
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highlandstag
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Re: How do I stop tappet noise?

Post by highlandstag » Wed Jul 11, 2018 7:41 pm

The lower edge of the headlamp panel - or upper edge of the lower valence.

unstable load
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Re: How do I stop tappet noise?

Post by unstable load » Thu Jul 12, 2018 3:09 am

Could you not be able to get enough movement by dropping the rear of the box to tilt the engine up?
Cheers,
John

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