knocking from engine boxster s
 

hi all, i have a boxster s 3.2 2001, i have a knocking from the engine only when the temp is up, i think its the oil once it gets up to temp it thins out and then the knocking starts, im using 5w40 mobil 1, any ideas before i change to 10w40 oil? cheers

Once the engine (and oil) is warm, a 5w40 oil should have more than enough viscosity to protect the engine (its not likely "thinning out" unless your engine temp is over 250). Changing to a 10w40 will not likely improve the viscosity (its 40 in both oils when warm).

The first thing that I would do is to have your front engine mount inspected, its probably worn out and making a knocking noise.

Detonation or ticking/valve train noise?

it only knocks when its up to temp and idleling, as soon as i put my foot down a bit it stops (when in motion there is no knocking)

Are you using at least 93 octane fuel. I once put in 91 octane in my Boxster by accident and I notice knocking at idle speed.

Is the knock most notable @2,700 RPM?

no the knocking only sounds when its up to temp and idleling/tick-over, when i put my foot on the acc it stops, my thoughts are that the oil is thining out when temp is up and when i put my foot down more oil go in and stops the knocking,,

Detonation, valve, or crank? Should be able to tell from the sound and where its coming from. A "tick" is probably valve related, but hard to say. You should post some audio/video.

I seriously doubt that its the oil viscosity.

Does the knocking change if you press in the clutch?

My engine knock turned out to be the water pump getting wobbly.

A light tick at idle may be injector noise

Does it sound anything like this: Clicking sound from engine bay - 2006 Cayman S - YouTube

it does not sound like a light injector tick, more of a knock, only happens when on tick-over around 800rpm and when car is up to temp, when 1st start and cold it purrrrs like a cat!!, the car is an auto-tiptronic, if its a mechanical problem sureley it would happen when i 1st start the car and happen all the time,, im gonna change the oil to a higher viscosity to see what happens!!

knocking on the wall?
 

Is that sort of knocking on the wall behind seats? It's heard after 10 or 15 minutes of warming up, specially while going on non-so-flat roads, more intense when stepping up accel. pedal, so to say...