knocking noise in engine

hello,
I have a question... my engine is making a loud knocking noise at startup and slowly lulls as the engine warms. by the time i am driving at 65mph it is almost gone, but still apparent. it seems to sound like its coming from the valve train. how can check to see where it is coming from to avoid going to a mechanic and pay lots $$$ to fix it?!!?!?

p.s. its a 2003 freelander 2.5 k v6 if that helps

yu sure its not the vis valves?

Could be piston slap, if one or more cylinder is out or misfirng?

The 1.8 k-series does it at peak torque 2750-3000rpm if one cylinder isnt quite right.

Hopefully its not a big end bearing

Edited after further reading - From your other post regarding coolant leak. Did the garage check pressure on each of the 6 cylinders? check your spark plugs for light grey/white deposits. This will be your coolant getting 'burnt' off. Possibly why you are getting piston slap.

LR1796, what did you mean? piston slap or pinging?, piston slap would be as much of a worry as bearing noise and ussually come togther

aussielander said:

LR1796, what did you mean? piston slap or pinging?, piston slap would be as much of a worry as bearing noise and ussually come togther

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Yes the two usually come together but not always.

Pinking is more of a crackling/sparking noise when accelerating under load, piston slap is more of a low frequency knocking noise. You tend to hear it whenever coasting in a low gear at around 2000rpm then slow acceleration. Also happens when cold.

A big end bearing just sounds like an awful deep tone thud

it only makes the knocking noise when i start the car and as the rpm and the engine warms, the noise gets softer. i believe it's still there after the engine is warm, but it just gets much softer and its harder to hear when driving on the road w/ other traffic. it is not a deep tone thud, more of a knocking. and the sound goes faster as the rpm increases too. so if i push the gas and go faster, the noise goes faster...

jseregos said:

it only makes the knocking noise when i start the car and as the rpm and the engine warms, the noise gets softer. i believe it's still there after the engine is warm, but it just gets much softer and its harder to hear when driving on the road w/ other traffic. it is not a deep tone thud, more of a knocking. and the sound goes faster as the rpm increases too. so if i push the gas and go faster, the noise goes faster...

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Its difficult to tell, and we're on the other side of the Atlantic.

Does it make the noise when engine on idle?
The piston slap noise can be heard through the bulkhead with the windows up.
If its related to the valves or tappets then this is a much higher pitched noise and usually you will only hear it with the windows down or standing outside the car, This is just a guide not a definitive answer.

any good car mechanic should narrow it down to a particular part of the drivetrain.

Stethoscope, or ear pressed against a long screwdriver is the trade secret.

I would still get your plugs checked and if any suspect white residue, I would follow up with a cylinder pressure test. It would only be about an hours labour cost.

If you have a Haynes manual or LANDROVER RAVE CD this will explain whats involved. The pressure gauge is about £25-30 ($- dunno), plus you'll need the long stem adapters for the KV6 block, the plugs are deep seated as in the 1.8 K4 engine