Tappety-tap-tapping
Discussion
Folks,
My 4.5 engine runs very smoothly but as it warms up the tappets start to tap - audibly, within the car. Once hot they sound like they would need adjusting, were they on another car. I am aware they are hydraulic and so cannot be adjusted.
The power etc is fine but what is the likely cause - any guesses? It is regularly serviced and has no other significant issues (of which I am aware).
Many thanks,
Rich
My 4.5 engine runs very smoothly but as it warms up the tappets start to tap - audibly, within the car. Once hot they sound like they would need adjusting, were they on another car. I am aware they are hydraulic and so cannot be adjusted.
The power etc is fine but what is the likely cause - any guesses? It is regularly serviced and has no other significant issues (of which I am aware).
Many thanks,
Rich
may be blowing exhaust manifold gaskets 
My engine also has a very faint chattery sound to it, and I was once told that the cam shaft might be worn. But a dyno run suggested otherwise, with 276 bhp from a supposedly unmodified 450. It could be that it's already had a new cam shaft and the preload wasn't set perfectly. Before condemning your cam shaft, I'd get a dyno run done on a respected rolling road.
I presume that your oil pressure is ok, I always thought that if the cam was worn it would "tap" when cold then quieten down a little, but to get louder as it warms up would suggest something other than cam, maybe worn rockers or even little ends. I believe you can check the cam with the sump off.
As others have said don't exclude the exhaust, a crack in the manifold at the 4-1 section is common.
As others have said don't exclude the exhaust, a crack in the manifold at the 4-1 section is common.
Dr Mike Oxgreen said:
It could be that it's already had a new cam shaft and the preload wasn't set perfectly.
That happened to me... the cam lasted 3000 miles before it lunched itself.If the OP is lucky (financially) it'll be manifold gaskets. If he's not, it'll be time for a new cam (IIRC the 450 has vernier pulleys).
When mine was re-done it went to V8D for an MC1. Made some good numbers afterwards too.
Use a short piece of garden hose to ear hole to listen for tap tap exhaust manifold blowing around the plug gasket area. Mine did exactly this on warm up.
When 1/2 inch of gasket finally blew on NO 1 cylinder on tick over it sounded like a RR Merlin V12 on tick over. Relief it was not a piston. You may be able to use your stethoscope for this Richard. Or pop round and I will have a listen. I made a temporary job fix with metal plastic padding then renewed the gasket myself.
When 1/2 inch of gasket finally blew on NO 1 cylinder on tick over it sounded like a RR Merlin V12 on tick over. Relief it was not a piston. You may be able to use your stethoscope for this Richard. Or pop round and I will have a listen. I made a temporary job fix with metal plastic padding then renewed the gasket myself.
Edited by EGB on Friday 27th September 10:17
I had this exact same problem with my Chimaera 4 litre. We suspected the hydraulic tappets - had these all changed and checked the pads on the rocker arm all present and correct - once reassembled the noise still came back. It would be OK when cold but once the engine warmed through the tapping noise could be heard again. It definitely was not the exhaust manifold so I took the car to somewhere else.
It turned out to be one of the rocker arms - it was not the pad but at the other end is a pressed-in cup where the push rod sits. The cup had worked loose in its housing and this tiny movement caused that horrible tapping noise. I could not believe it myself but the mechanic pushed the end of a nylon cable tie into the cup and was able to move the cup up and down within its housing. We replaced the rocker and all was good.
Hope this may be of some help
It turned out to be one of the rocker arms - it was not the pad but at the other end is a pressed-in cup where the push rod sits. The cup had worked loose in its housing and this tiny movement caused that horrible tapping noise. I could not believe it myself but the mechanic pushed the end of a nylon cable tie into the cup and was able to move the cup up and down within its housing. We replaced the rocker and all was good.
Hope this may be of some help
R3UMP said:
I had this exact same problem with my Chimaera 4 litre. We suspected the hydraulic tappets - had these all changed and checked the pads on the rocker arm all present and correct - once reassembled the noise still came back. It would be OK when cold but once the engine warmed through the tapping noise could be heard again. It definitely was not the exhaust manifold so I took the car to somewhere else.
It turned out to be one of the rocker arms - it was not the pad but at the other end is a pressed-in cup where the push rod sits. The cup had worked loose in its housing and this tiny movement caused that horrible tapping noise. I could not believe it myself but the mechanic pushed the end of a nylon cable tie into the cup and was able to move the cup up and down within its housing. We replaced the rocker and all was good.
Hope this may be of some help
Good call, this may be the mysterious tapping a lot of people get, and should be an easy check and fix It turned out to be one of the rocker arms - it was not the pad but at the other end is a pressed-in cup where the push rod sits. The cup had worked loose in its housing and this tiny movement caused that horrible tapping noise. I could not believe it myself but the mechanic pushed the end of a nylon cable tie into the cup and was able to move the cup up and down within its housing. We replaced the rocker and all was good.
Hope this may be of some help
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