Thread: 3.9 upper valvetrain oiling

The oil is fed into the rocker shaft via the rear pedestal on the LH head and front on the RH head.
The block is gun drilled from a main oil passage directly upwards.
You should look if there are any shims under the pedestals as the rear shim must be relieved to let oil upwards, and this may not be apparent to a newby.
Its obvious when you have the rocker pedestals off.
I cannot think of another way for there to be a blockage unless there is some swarf in the oil passage. Maybe stick a rod down it .
The other thing is that if the rockers and shaft are really worn the oil can spill out of the rockers nearest the oil feed and starve the other end.
You have to dismantle the rockers from the shaft to see any wear as it is only usually on the bottom of the shaft.
Regards PhilipA

Hi the rocker shafts are also handed, meaning they have to be put on the right way otherwise you will restrict the oil flow. The workshop manuals describe cut marks on the front of the shafts indicating front or back. I cant remember which is which but look in the workshop manual!
Brad🙂

Ok thats something to investigate further.

I've never had the rocker shafts off, so P.O's mechanic was last one to fiddle, if there was any fiddling or shimming.

I think the shim theory might be pretty close to the mark, So I'll look into that, as well as the rocker shaft orientation.

Thanks!

I found the oil galleries in many of the rockers were completely blocked when replacing head gaskets a while back. I used a pin chuck and number drill to unblock them.