My cousin just bought this g35 coupe 6speed 2003 2 days ago WITHOUT me coming with him from a private seller on Craigslist and the motor was knocking REALLY REALLY BAD as he pulled up to my house I thought it was the timing chain but it sounds like the valves.... Any input, cost, solutions, to fix this would be helpful thanks guys

 

wow, but then again for 5000 i'd prob buy it too

 

I'm assuming you checked the oil level already? How many miles on the engine?

 

127,000 miles oil level is good but the knockin noise is coming from the heads in the engine bay

 

No offense man we need a better video than 2-3 seconds of you standing 5 feet away from the engine bay. Pop the hood and give us a good 30 seconds of where the noise is the loudest, and have the engine revved a couple of times. Also, does it do it when it's cold only? Go away after warm up? Get worse as it warms up? etc...

 

Sounds to me like a dry lifter it's more of a tap then a knock

 

Dry Lifter ?

It has DOHC with cam followers, there are no hydraulic lifters.

 

Ha your right my bad, could be worn cam followers or a wore cam lobe there is no telling if the previous owner didn't watch the oil and it might have starved it for oil

 

Like Darkstar said post a better / longer video.

Check for signs of prior oil leaking from the valve covers and do an oil change with conventional (non synthetic) oil and see if it's blowing blue smoke. Also pull the spark plugs and see if there's any oil on them or pooled there.

Best first guess is that it's got some form of O/C and it's possible the previous owner let it run low enough to damage to the valve train, but figuring out why and where it's got the O/C (if it does) is your first priority. The first time I realized I had O/C problems was with a light valve tap, thankfully I was close to home when I heard it and did an oil change right away and saw that it was very low after about 1500 miles. If the last owner didn't keep it topped off or catch it in time you might need to look at a rebuild.

Of course it's possible it's just a jacked up valve train from age and the rest of the motor is fine. I jump towards assuming O/C because I've got it and it's not uncommon. Also over the course of diagnosing an O/C issue you're likely to find whatever else is wrong, whether it's consuming oil or not.