[TR] Tr6 - no oil to rocker shaft (Long post)

[aribert neumann]

Greetings all:

Spit boded GT6 w/ a 2.5L motor, about 80K miles on full rebuild, about 15K
miles on head gasket (blown) & cam (several wiped lobes) replacement.  A
month ago one morning I noticed that there was no indicated oil pressure at
hot idle.  Above 2000 rpm oil pressure was just over 10psi/1000 rpm (lower
than normal).  I checked the oil level and listened for rod knock.  Oil
level was good and there was no rod knock so I drove it home (about 40
miles).

The screw that retains the rocker shaft had backed out and starved the
rockers downstream of oil.  This is a phillips headed countersunk screw - I
should have used lock-tite.

I replaced the rocker shaft / rockers.  The new rocker shaft had set screws
in the ends instead of pressed in plugs.   I went to remove the screws to
make sure the inside of the rocker shaft was clean of machining debris.
The set screws were only finger tight - beware if you are replacing a
rocker shaft in the future to check for loose set screws!

Now I am not getting oil to the new rocker shaft.  Cold idle oil pressure
is 80+ psi and hot idle is down to 8 to 10 psi (was about 20 PSI earlier)
but with engine hot, at 2K rpm oil press is 45 psi (about the same as
before).   Oil is just oozing out of the rockers.  Blipping the throttle to
2K rpm without the valve cover in place and there is no oil spray on the
firewall.   I removed the oil port plug in the head and started up the
engine (cold) and less than a teaspoon came out in about 30 sec.

The mechanical oil pressure gauge is tapped into the oil galley at the
distributor.  The oil to the head is fed via the cam at the rear most cam
bearing (block was line bored and has Spit cam bearings).   The cam meters
out the oil that travels up to the head. Did the rear cam bearing get
starved for oil when the rocker shaft screw came out?   I am trying to
predict the damage before I pull the engine to dismantle and inspect - no
time to do so now.