Today at Atelier Kaz - ex-Honda R&D, F1, Indy/CART engineer

Started to remove the valve cover.

I was hoping that the leakage was from the corner of the valve cover gasket
above the #1 cam holder so that I don’t need to remove the cam shaft.


Unfortunately, it was not the case and the valve cover gasket was
really stuck on the cyl head and cam holder surfaces that I had to pull it off
using some force.

Once again, it just confirmed that the liquid gasket that I use has really
good performance even after many years.

I took above photo after pulling off the gasket from the cyl head and then
placed it on the valve cover to show that the liquid gasket and the rubber gasket
were stuck really well at the #1 cam holder.


So, unfortunately, I have to remove both cam shafts at the rear bank
in order to replace the brown cam seals because that’s the only place
it can leak the oil.

It makes sense that I didn’t see the oil when the engine was just
warming up and at idle rpm or even after a few TH blips because
that area is not under any oil pressure and the oil is just
splashing/flowing behind the seal.



While removing the parts, carried out several inspection.


The #5 spark plug showed extra corona arching compared to other cyl.



The air filter is still fine but please consider replacing it some point next year.



Due to the limited space, it was not easy to see the cam seal even
using the mirror before removing the cam shaft but from the trace of the oil,
it was leaking from the intake side of the cam seal.
From the marking on the cam seal, it was pressed in with some angle.

I was initially under the impression that it would be the cam seal at the
exh side because that is the one you have to twist your body a lot but
finding that it was at the intake side, once again, it confirmed the golden rule.
Although I have been working in very stressful environment but rewarding
racing world for over 20 years and love every challenge,
do not carry out the delicate task under massive pain....

From what I can see, the cam seal was inserted with some angle and not
square to the recess.
The camshaft itself is floating on the engine oil inside the cam holders and
it has tiny-tiny side way movement (ie., in the direction of both rear tyres).

So, during the test driving session many years ago, the cam seal was still
doing its job and no oil managed to seep through the area but after many
miles, the tiny-tiny side way movement of the cam shaft managed to slowly
move the cam seal and finally created enough gap for the oil to seep out.

You can see the trace along the green arrows.


There was no other trace of the oil so happy with my diagnosis.



As a pre-caution, I removed the cam pulley at the front bank and
double checked that both cam seals were sitting square with no oil leakage.


Time for the reassembly.



New o-ring under the #1 cam holder.




There is no space to put the camera at the exh side and just managed to
take this photo at the intake side of the rear bank cam shaft.
Brown seal inserted properly this time.



Both cam shafts back in place.