pgs

Hi mates,

My mechanic is changing the oil gallery gasket due the well know low oil pressure problem on HR engines. As the front cover is removed and the engine has 230.000 km, he check the primary chain. It is stretched. So he remove the camshaft sprockets in order to change all 3 chains plus guides plus tensioners.
Then he realizes a very high wear on timing sprockets (4 cam gears plus crank gear). I didn’t make photos yet, but the wear are similar to the photographs attached found on the net






The wear mark are simetrical on both sides of every teeth (if due to chain tension, it should be not simetrical), the 3 central plates of the chain seems to make wearing marks on the sprockets with a depth something between 0.1 and 0.3 mm. The marks are smooth without metal burrs.

Surprisingly, if search in google images the part nº of the sprockets (13025-JK20B, 13025-JK21A and 13021-AL51A) you can see many of the new sprockets sold also have this marks from factory (but is difficult to see if are only brightness differences or the marks are really deep). And the other 50% of 350zHR sprockets sold on the web dont have any mark on the teeth



This 4 sprockets are very expensive (2000€) and the Workshop manual said that if you change the exhaust sprocket you have to change also the Variable Valve Timing Cover (because the magnet retarder brake/friction pad I suppose), this is 1000€ more

So, the questions are: have the OEM sprockets this marks on the teeth when new?
Is usual have to change the timing sprockets in this engines?

Thank you very much for the help

Xrabbix

I changed the sprockets on a 2007 g35 with the HR and never changed the vtc covers. Runs fine 50k miles later.

My understanding is the vtc covers just contain something similar to a small clutch, so if they aren't worn out I wouldn't blow the $1000+ to change them.