4.6 thor v8 knocking

Hi everyone, Im running a 2001 p38 4.6 v8 and have noticed a knocking noise when started from cold which lasts approx 5 seconds then is gone until cold started again also seems to be ticking over lower than normal-any ideas?

Hydraulic tappet or slipped liner

Sounds expensive , better get it booked in the garage!

fanatic said:

Hydraulic tappet or slipped liner

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Slipped liner will manifest once engine is warm, not from cold.

lazy hydrualic tappet try an engine oil change maybe try 20/50 mine has a tappetty sound but its constant hot or cold.

think its time for an upgraded cam

Also it has been known for exhaust manifold gasket to make similar noises

Thank you all for your replies, the range is at the garage and going under the knife tomorrow. Fingers crossed it wont be too heavy on the wallet (I can dream) and Ill let you know the outcome.

What was the outcome?

pete969 said:

What was the outcome?

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Went under the knife but didn't survive.. Morto

discool said:

Morto

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Really - how come? Completely dead?

On the Thor engine there are two knock sensors, one each side of the block.

If either are faulty the ECU won't know it has gone too far with the ignition advance in the morning, one thing to check.

Mine does it in the winter but as it is warming up it goes away, or if I run it for a minute before pulling away. It is a piston speed knock but clears completely in a hundred yards or so and won't come back until the morning. It only knocks under load.

Peter