Tappet Racket

[R3UMP]

I know this seems a much talked about subject amongst these forums so my appologies for bringing it up again, I have looked through past posts but I'm still a bit miffed as to what this noise can be. I have a 98 Chimaera with 36K on the clock, the car has been very well cared for as the service history suggests, it's last service being carried out at Austec and is topped up with their 10-40 engine oil. The problem I have is a tappety noise coming from the near side rocker cover, this has been identified and pin-pointed with a stethescope by a trusted mechanic who has a good knowledge of the RV8 engine. It was diagnosed as a leaky lifter.

When the engine is started from cold the noise is not there. As the unit warms the noise gradually becomes apparent before it's got to full temperature. The exhaust manifolds have been checked and it is not those, these would make a noise when cold and get less noisey when hot and expanded presumably?. I have had all of the hydraulic lifters changed for good quality ones from TVR Parts.com, at the same time the camshaft was checked for wear but was in excellent condition. The small steel pads in the rocker arms were also checked for missing ones - they were all present and correct. Everything looked as it should.

I don't think it can be the bearing in the belt tensioner pulley either as that would make a noise straight away as soon as it's turned. I have also checked the belt for trapped stones etc but to no avail. I'm now running out of ideas and money. I know it's not a serious problem, most people say just ignore it, but I really want it to be right. I love this car and want to enjoy it to the max

any help would be greatly appreciated

[poorpeet]

I have to say that it really sounds like one of the manifold gaskets is blowing rather than a cracked manifold. Mine was also much quieter when cold. It's not a big job to change them, it will rule it out as a cause & its a hell of a lot cheaper than pulling the top end apart to investigate.

Good Luck

Pete

[r3ump]

Thanks for the reply Pete. I think it would be a good idea if I had these changed just to rule them out. So yours sounded like a metallic tapping when the engine warmed up, when you had these changed it cured the noise completely?

Nice colour car on your profile BTW

[Cider Andy]

Yes, that's exactly the noise you can get when a gasket manifold has failed: a metallic tapping.

[r3ump]

Thanks -

When a stethescope is applied onto the rocker cover it really sounds as though the tapping is coming from the top end. Can this tapping noise travel and appear to be coming from the tappets. Do you know how long a garage would need to change the gaskets? - I'm beginning to think I should just get these changed. The thing that does not make sense to me is surely they would make more noise when cold - not when hot and things have expanded a little

[poorpeet]

Yes it can be very difficult to pin down a noise. When the engines running there is so much thrashing around making noise its hard to pick anything out. Changing the gaskets is not in itself at all hard. Its just a bit of a fiddle due to the restricted access. You can replace the standard fibre gasket with upgraded steel ones from any Range Rover garage. Why not have a go?

[poorpeet]

Just looked at your profile & seenthat you are in Kent. I'm in mid Kent & I'd be happy to meet up & talk you through it.

Pete

[M@H]

Hmm.. I know this will sound pedantic but the sound of a manifold gasket blowing is more of a "ticking" than a "tapping" to me.. [/pedant-off]

[r3ump]

Thanks Pete, that's very good of you

Maybe I could pop the car out for a run and let you have a listen see what you think. It's a bit difficult to define whether the noise is a definate metallic tap or more of a tick. Perhaps I should mod the exhaust instead and drown out all other engine noise and forget about it!.

[poorpeet]

Email me via my profile. Don't leave it though. If it is the exhaust gasket the leaking gas will erode the head over time. If this happens it stops being a simple job!

Pete

[dempsey]

My symptoms were exactly the same as yours, except - as M@H pointed out - the noise was more like a ticking than a tapping. It was the nearside exhaust gasket which would have been fairly minor except in getting the manifold off two bolts sheared as the TVR factory assembly hadn't used copperease. In the end the engine came out to drill and retap the retaining bolts. Cured the noise though.

[r3ump]

Thanks for all of your advice. To be honest I'm still a bit miffed - I have just spoken to the garage that done the engine work and they are 100% sure that it's not an exhaust manifold problem as they checked this out a couple of times to be sure.

[ray_von]

Just to cheer you up these are EXACTLY the symptoms I had and also had the don't worry ignore it messages. One new cam then short engine later and the noise has gone. The problem turned out to be a bent crankshaft
Have a good 'un

[big_treacle]

I had a ticking sound on my Chimaera. Diagnosed as a knackered exhaust manifold gasket. Changed it & had the exhaust wadding removed at the same time. It was so loud after that you couldn't hear if the ticking had gone or not

[r3ump]

That's a good idea - 'if in doubt - drown it out!' I like your thinking. I was trying to think of a way to justify a louder exhaust system - I think I've just found it!

[ubernoober]

big_treacle said:

I had a ticking sound on my Chimaera. Diagnosed as a knackered exhaust manifold gasket....

Me also, sounded more like a 'tacking' sound - harsher than a 'tick' - but it turned out to be two holed manifolds anyway! Just had them fixed at Fernies, damn fine job, most reasonably priced!

[damol]

Out of interest how much does it cost to replace the exhaust manifolds as I think my LHS have gone.

[IPAddis]

A 1998 car with so few miles is at high risk of the rusty camshaft problem. If left for a long time, the oil drains from the cam and the hardened coating can rust. This is often mentioned as the reason why so many cams need changing at around 30k miles.

Changing the lifters without changing the cam is generally a bit of a no-no. See "Replacing worn tappets and cams" here: www.v8engines.com/engine-4.htm#worntappets

I suggest a new cam from V8 Developments.

Ian A.

[M@H]

IPAddis said:

A 1998 car with so few miles is at high risk of the rusty camshaft problem.

That totally depends on haw it was driven. The car has been averaging £4k a year and I think doing 300 miles a month with usage every week would negate the "rusty camshaft" theory entirely. If it did 3 months on the road and 9 months off then I'd go along with it but you cant just diagnose fitting a new cam on the basis of it having done 36,000 miles.

Cheers,
Matt.

[ubernoober]

damol said:

Out of interest how much does it cost to replace the exhaust manifolds as I think my LHS have gone.

Both my manifolds were holed - cheapest option was to have them repaired, this cost £60 + VAT each side, add in gaskets labour etc at £200 makes it a reasonably priced solution.

Asked about SS ones - apparently around the £1K mark!