Cylinder head wear...

[Rawze]

(07-06-2017 )un_yun Wrote:  I'd replace the cam and any rollers that don't pass inspection. As far a bearings go, well I'd probably replace them too. Per cummins they can run as long as copper is no more than 180* of the inside of the bearing. I don't know that I would worry about the head if it was running good, with no oil or coolant loss.

I have also seen many times where injector cam bearings worn will cause oil seepage out of the front of the head behind the gear train. That is always a good indicator that they are done even before taking anything apart.

(07-06-2017 )Hammerhead Wrote:  ...

With a higher mileage engine, and since you're not doing rods & mains at this time, I suggest 9 dimes. Valve guide seals, good call since you're already in this far. Enjoy your wonderful weekend.
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It sounds like a good idea to increase oil pressure on an old engine but there are risks. I would suggest 8 dimes at most on an old engine actually. 6 being more on the safe side, or 6 on an engine with only one overhead cam. The reason is that I have seen a few where the flywheel housing starts to leak after increasing oil pressure. This is because the gaskets are old too and the extra oil pressure is extra strain on this gasket. The more you increase oil pressure, the higher the risk of it suddenly starting to leak.

Here is that cross-channel. Only the rear flywheel housing gasket stops it from leaking and there is a lot of oil pressure in this area...
   

A second reason for this area to leak oil on the engine is where the engine has been driven very hard, or if someone has the horsepower turned up high on one. The rear engine mounts are on the housing, not the engine block, and the strain on it can be immense if the HP is up or someone is always driving the truck hard. The flywheel housing is also cast aluminum too, and tends to have a lot of give to it on its own under high torque. Almost seems like a weak-point in torque transfer to me but what do I know eh?

This is also the most common place, but also worst possible place that I can think of to get an oil leak after increasing oil pressure by shimming the pump. A person would have to drop the front of the drive-shaft, then remove the shifter, transmission, clutch, flywheel, oil pan, starter + disconnect batteries, jack the engine up and support it by the bottom of the engine block itself (hence removing the oil pan), also remove the rear main seal, motor mounts, the flywheel housing, then finally get to the gasket --- all just to stop this leak.