OzGTR
21-11-2016, 10:11 AM
Hi All,
I've just removed my inlet manifold to have it cleaned up and painted, and noticed that the two inlet valves in cyl 3 have some discolouration on the valve stems immediately belowpingthe valve guides.
My first thought was that it was possibly PCV junk, but cyl 4 that gets an 'equal' share of the PCV gasses looks totally fine. There is also a very distinct sharp edge at the bottom of the discolouration that makes me think this is abrasion causing some heat?
This is an R33 GTR motor that is stock (except for cams and a little extra boost) and in otherwise good order and showing nothing as wrong in its performance or behaviour.
I'm no expert, so I thought I'd ask, can anyone identify what the likely cause of the discolouration is, and if I should be looking at head job? Everything else looks very clean.
Im about to bolt on some -5 turbos+supporting stuff so I figure this might be something that needs a look.
Photos here: http://imgur.com/a/mtn1x
I've attached a picture of cyl 3, and one of cyl 2 for reference - the rest all look like 2.
Edit: I've realised the rest of the valves are closed. Motor is at TDC on cyl1. I need to turn the motor over and observe each valve stem when the cam pushes the valve open to see if others have the same marks... still keen on advice!
Cheers!
-Shaun
I've just removed my inlet manifold to have it cleaned up and painted, and noticed that the two inlet valves in cyl 3 have some discolouration on the valve stems immediately belowpingthe valve guides.
My first thought was that it was possibly PCV junk, but cyl 4 that gets an 'equal' share of the PCV gasses looks totally fine. There is also a very distinct sharp edge at the bottom of the discolouration that makes me think this is abrasion causing some heat?
This is an R33 GTR motor that is stock (except for cams and a little extra boost) and in otherwise good order and showing nothing as wrong in its performance or behaviour.
I'm no expert, so I thought I'd ask, can anyone identify what the likely cause of the discolouration is, and if I should be looking at head job? Everything else looks very clean.
Im about to bolt on some -5 turbos+supporting stuff so I figure this might be something that needs a look.
Photos here: http://imgur.com/a/mtn1x
I've attached a picture of cyl 3, and one of cyl 2 for reference - the rest all look like 2.
Edit: I've realised the rest of the valves are closed. Motor is at TDC on cyl1. I need to turn the motor over and observe each valve stem when the cam pushes the valve open to see if others have the same marks... still keen on advice!
Cheers!
-Shaun