I had another idea... I haven't had a chance to look, but it would be possible that if the timing belt was loose/slipping/or missing teeth then it could be causing the cam to shimmy unevenly around its axis of rotation?

I won't be able to pull the belt off easily to see though... I'll have to look and see if there are any obvious signs...

 

ktk, when were those cams installed? Did they originally have a black finish to the lobes (check the non-contact surface of the lobe)? I recall a thread 4 years ago ....

 

ktk PM me i have some very interesting material for you.

 

I don't think they have the black finish... These dudes were installed back in '05. I think before the GSC S2 days.

 

It looks like an oiling issue at first glance. notice how the lobes are black from heat......cams should not be getting that hot haha......do you have an oil pressure gauge in there?

 

already sent him a PM. :-)


I have seen this issue before and i'd love to get to the bottom of what actually causes this type of falure. If i'm looking at the picture correctly these are the first batch of 4G63 cams we ever sold.

 

Yea i suppose its possible low oil pressure is an issue, but i have a full set of Defi gauges and oil pressure has never behaved usually. Cold starts fires rite up to 90psi and then warms up to 10-15psi idle. Oil is changed regularly with mobil 1 10w30...

 

should i be worried about this happening to my S2's ? i havent installed them yet but they were purchased in july 08 if that is of any concern.

 

NO you shouldnt.. these are GSC 272s WAY before the S2's ... and you barely ever see something like this happen.. period.

 

Pics of my S2 cams installed in Oct 08. Pics take in Jan 09.

 

good lord! and i thot I had it bad

 

holy crap! I think I'm gonna go back to the stock cams after seeing this thread.

ktk: how did the ticking sound like? loud as hell? cause most cams seem to give a somewhat loud ticking noise compared to the stockers.

 

What was determined to be the cause of that?

It's been years since I have performed metallurgical failure analysis, but that bottom picture shows signs of a fatigue failure, origniating at a point just to the right of the bottom most hole. Of course, this is just from looking at that one picture and what looks like 'beach marks' at that origination point.

If that was the case, it could have been a defect at that particular point and/or installation error/imbalance.

I'm curious what the cause was determined to be? Makes me miss my materials engineering/failure analysis days.

 

It had a pretty loud ticking noise that was audible from inside the car with the fan and radio off. I have 3" turbo back so teh car is quite loud but still you can hear the ticking and u could year the ticking and its frequency was directly related to rpms.

That said, before the ticking started, my valvetrain was silent. I never had nay ticking before and it was an obvious and huge difference when this ticking started. The valvetrain was built by JAM using titanium dual spring valves and retainers and JAM spec lifters.

 

what happened here ?