Does anyone have any knowledge about a piston knocking noise in the Magna 6G74 engines. My motor is making a rattly knocking noise which is loudest between 2-3000 RPM with light to moderate load when hot. Noise varies as you feather the throttle.

I reported this to the dealer who could not fault it but had a MMAL rep drive it and I was told it was gudgeon pin noise but he was not concerned about it. Should I worry, it sounds sick but motor is running ok at the moment.

Any knocking noise from a motor is something to be concerned about.

A couple of questions for you -

How much oil is in the engine?
When you can hear the knocking, how fast is it?

"Gudgeon pin noise" is code speak when a mechanic really doesn't know what it is. He is hoping you will be scared by the potential cost of stripping down the engine to its innards and you will just go away. Real gudgeon pin noise means the piston is being hammered and is likely to fracture. I would check that the noise isn't coming from somewhere else, I would start by taking off the ancillary belts and running the engine to eliminate possible knocking noises from the alternator and power steering pump. Use the stethoscope trick to try to locate the noise. Could also be hydraulic lifters. Lift the rocker covers and see if any have collapsed or valve stem ends have been hammered. It's a process of elimination. Best doing this yourself as a mechanic will charge you for every minute he spends scratching his head not getting anywhere. At worst you can keep driving until the problem becomes more obvious and easier to locate.

Try a thicker oil.

Any knocking noise from a motor is something to be concerned about.

A couple of questions for you -

How much oil is in the engine?
When you can hear the knocking, how fast is it?


Oil's fine, Sits on the full mark at op temp. Filter & oil changed about 5000k ago and is 15W40 according to the paperwork.

How fast? I'm not sure if you are referring to road speed, engine RPM or the rhythm of the noise .
However, Road speed has no bearing on the problem only RPM & Load. I would Say anywhere from 1500RPM up to 2500RPM roughly.

Can be heard at cold but is more pronounced at op temp especially with the convertor locked up. Varies in intensity as you feather the throttle inputs. If you are just cruising at 2000RPM at 100k it's not too bad but as soon as you require acceleration it intensifies. The rhythm of it to me sounds like it's 1 piston not 6 making a noise.

Try a thicker oil.

Be careful as pinging can sometimes be mistaken for gudgeon pin rattle

It usually only happens as you load the engine though and normally is cured by resetting yur base timing.

Be careful as pinging can sometimes be mistaken for gudgeon pin rattle

It usually only happens as you load the engine though and normally is cured by resetting yur base timing.

Is this a MUT procedure or distributor adjustment? Maybe i should try Higher octane? I don't understand why the timing would need resetting all of a sudden?

Try a thicker oil.

Maybe worth trying, only noticed this since this last service but maybe a little warranty expiry paranoia but it does not sound right. Definitely most audible at operating temp. What grade are you thinking, I generally don't like going above 15W. I am going to an engine rebuilder to get a second opinion though.

My TL is also noisy in a mechanical way....especially at the revs mentioned but in all gears. There is no tappet noise at idle and if the motor is revved, the loudest noises are from the drive belts making a whirring kind of noise...which is nothing like the noise made when driving. I'd imagine the engine has knock sensors(?) so that should rule out pinging, and the noise is too busy to be coming from one bearing/gudgeon/piston....foot to the floor and it sounds more like a sewing machine and really goes!
If I compare it to me previous car - a VS Commodore, it is very noisy. But then I figure that the Commodore had a cast iron block and head plus a double firewall to silence engine noises. The Magna has a single firewall, minimal soundproofing and the engine is all alloy (remember chaff cutter aircooled VW's). So I really think it's normal...at least I hope so. It hasn't changed in the 3000km I've had the car so in the absence of other signs I'm going to live with it (and carry a rabbits foot).
Final thought - bought oil and filter from local Mitsu agents - $29 for 5l of 15W50 incl filter....asked why not 15W40 and they said you need the 50 bit to quieten the engine once out of warranty. He seemed to know what he was talking about but then again so was the bloke who sold me aluminium cladding for the house.

My TL is also noisy in a mechanical way....especially at the revs mentioned but in all gears. There is no tappet noise at idle and if the motor is revved, the loudest noises are from the drive belts making a whirring kind of noise...which is nothing like the noise made when driving. I'd imagine the engine has knock sensors(?) so that should rule out pinging, and the noise is too busy to be coming from one bearing/gudgeon/piston....foot to the floor and it sounds more like a sewing machine and really goes!
If I compare it to me previous car - a VS Commodore, it is very noisy. But then I figure that the Commodore had a cast iron block and head plus a double firewall to silence engine noises. The Magna has a single firewall, minimal soundproofing and the engine is all alloy (remember chaff cutter aircooled VW's). So I really think it's normal...at least I hope so. It hasn't changed in the 3000km I've had the car so in the absence of other signs I'm going to live with it (and carry a rabbits foot).
Final thought - bought oil and filter from local Mitsu agents - $29 for 5l of 15W50 incl filter....asked why not 15W40 and they said you need the 50 bit to quieten the engine once out of warranty. He seemed to know what he was talking about but then again so was the bloke who sold me aluminium cladding for the house.

Pretty sure the ecotech were iron block/alloy head. The 6G74 is also iron block/alloy head. I've had a 6G72 gen3 which was horrible cold (piston slap) but ok warm although probably a lot of induction noise too but this is a knocky noise not like the usual induction throaty sound. The Gen 2 V6 I had was defintely so much quieter even with heaps of k's on it. So long as it does not get worse in a hurry I'll live with it but just a little concerned if a piston or rod is about to let go, that would not be nice.

We're both wrong - Ecotec V6 is definitely all cast iron and 6G74 does have a cast iron block. I was sure it was all alloy :facepalm
I've also thought that maybe it was an exhaust leak - maybe where the the headers bolt to the heads or where both banks join or even part of the double wall exhaust insulation setup vibrating. I suppose what needs to be done is drive a similar Magna and see what it sounds like.

Just had another thought - someone in the AWD forum said they replaced their upper engine mount at 90KM as it was totally knackered. I know from Commo days, that a collapsed mount causes bad vibrations/engine noise when power is on due to no damping, so is it possible that a knackered top engine mount results in the engine leaning over on mild/moderate acceleration allowing metal to metal contact with all the associated bad vibes? Mine looks OK but I'm not sure how you tell if they are knackered????