tapping noise from front of engine

[gammav]

Got a tapping noise, which appears to come from the front of the engine...

Not audible under load or when on the move, but when standing still with a little blip of the pedal...the ticking clattering noise rises/emerges as the revs fall and the exhaust note dies away then carries on quietly as the engine idles.

Did a search and read quite few threads re leaking exhaust manifolds and had RV8 in a P6 with a blowing manifold many years ago which sounded like a steam engine under load... this sounds different, though I'm not ruling a manifold leak out as recent 12k service at HHC included "tightened loose manifold bolts".

Oil pressure and coolant temp holding steady...blood pressure set to rise

Any thoughts?

[clive f]

does the noise occurr when the engine`s cold, warm or both?

[Barkychoc]

Get a piece of pipe, stick one end in your ear and listen around the manifolds to see if you can hear a leak.
They can also leak where the 4 pipes join, try getting someone to hold a rag over both exhausts to see if you can hear it hissing where the pipes meet.

[gammav]

The noise is present when engine both warm and cold...possibly more noticeable when cold,

Tried the hose method but still difficult to tell where its coming from...think it sounds more like rattle than a manifold tick as tends to be less with a few revs then rattles as the revs die down.

I'll give Hexham a bell in the morning...or maybe RP wood as they are closer.

[steve-V8s]

Try popping the alternator belt off and briefly ( because the water pump will not be running) try the engine to see if the noise is still there. A small stone stuck in the belt can make a surprisingly loud ticking sound. Also the bearing in the spring loaded idler can make a similar noise.

[Aussie John]

If it clatters after a blip of throttle maybe timing chain?

[Milky400]

dont all hydraulic lifters clatter slightly, especially if you use a thin grade oil?

Has this happened since the service? as the oil used may have been thinner than previously used.

Had a rattle/clatter from mine, and in my eyes it was never there before so started getting a little paranoid making it louder as i was always listerning for it. After having it checked out all was ok and the noise was perfectly normal

[FlipFlopGriff]

Exhaust gasket maybe? I've not had one go but think they tend to be more of a ticking noise.
Oil is a good shout. I change the oil & filter now and use 15/50 Silkolene (or Titan as it's called now) and it seems to like that as low usage. I know some service agents use a 5 or 10 grdae which is too thin for the RV8.
FFG

[gammav]

12k Service (41k on the clock) at HHC a month ago...I asked which oil they used before hand and was told Mobil 1 15/50 so don't think its thin oil. Pretty much convinced its not a manifold tick either.

I'm off up to see them now so hopefully will get a diagnosis and not too expensive quote...

[ESDavey]

I had a similar rattle, turned out to the exhaust heat shield for the main belt had started to come apart. I would also look around the front spots, grill, etc for anything that could be loose.

[simonej]

Mine makes exactly the same noise and has done since I bought it. I gave up worrying a while ago and just assumed it was the cam chain or a bearing of some kind.

Stepping up the oil to 20w50 made no difference either.

[crashhelmet]

Its still better than an engine noise coming from your taps though.

[gammav]

The verdict at Hexham was don't worry "they all do that sir"...500s rattle a bit on over run?

Reckoned they once had a customer who couldn't live with it so had V8D rebuild/upgrade his engine...and the rattle was still there.

They offered to start a few other cars to demonstrate but I took them at their word...there's a local meet this weekend so guess I'll get to listen to a few other engines for comparison.

still wondering why I hadn't really noticed it before.

Thanks for the input chaps..much appreciated.

[marks3drtaz]

Conbination of cam walk and timing chain rattle nothing to worry about, Early engines without the cam retaining plate don't do it ??

[Alexdaredevilz]

Is it like this noise?

http://www.youtube.com/watch?v=RstjSrv9Iko

[gammav]

nope defo not a blowing exhaust/manifold...I'm very familiar with that sound from the old Rover P6 3.5 I had many years ago.

As posted above it appears to be an inherent feature of the 500... cam/timing chain rattle on over run.

[Milky400]

gammav said:

nope defo not a blowing exhaust/manifold...I'm very familiar with that sound from the old Rover P6 3.5 I had many years ago.

As posted above it appears to be an inherent feature of the 500... cam/timing chain rattle on over run.

And most RV8's that i have heard

[gateeast]

I've gained a tapping noise also. It goes when either the injector or spark plug is disconnected on the affected cylinder. It has affected the running on mine though.

Any ideas welcomed. Also, what psi should the cylinders be?