1973 IH 464 C175 gas engine not oiling rocker arm assemb

I had engine completely rebuilt with sleeves, pistons, rings, bearings. I also had the head/valves resurfaced. Rebuilt the oil pump. I have 30 lbs of oil pressure at the gauge, but no oil is reaching the rocker arm assembly. Please advise!!

Thats a 4 cylinder, right/If it is take out the center support bolt of the rocker shaft, and see if you got oil coming up there if not, must have a bushing out of alignment!

Not familiar with that engine and
routing of oil passage from pump to
rocker arm. But my guess is, its
plugged somewhere along the way, or
engine not put together right.
Did any gaskets get put on backwards,
end for ended, or upside down?
Blocking passage if wrong.
Were all bearings, bushings, and so on
that were replaced, the correct size
and within clearance tolerances? If
not, oil will travel to the place with
to much tolerance and no further.
Were bearings installed correctly?
Some bearings such as cam bearings
have to be installed with holes that
mach up with oil port holes. If not
lined up, oil passage beyond that
point will be blocked off.
Do you still have oil pressure? I have
installed new oil pumps right out of
the box, that completely went
defective after just a few minutes of
run time.
Also, how long did engine run, before
you noticed no oil at rockers? Being
at the top of the engine, and likely
the end of oil passage ways, the
rockers are the last to get oil flow
from the pump. Might take a bit for
oil to get there. A minute or so
(especially if pump, filter, and
passage ways are full of air).

(quoted from post at 10:11:14 12/06/21) Thats a 4 cylinder, right/If it is take out the center support bolt of the rocker shaft, and see if you got oil coming up there if not, must have a bushing out of alignment!

Click to expand...

Yes it is 4 cylinder. I assume by your answer that the oil would be pushed up by the camshaft/bearing. I will check. Thanks

Yes if that is the route of the oil, it will have a hole down the center of the bolt, or a cut along the edge,and that allows the oil to get to the rockers!

Thanks for reply. I can't validate whether bearings were in spec. I would assume so, since the machine shop that did the work has been in business for 20+ years. I am checking the center rocker bracket 1st to see if oil blockage is caused by head gasket being installed incorrectly. Yes, I have 30 lbs oil pressure at the gauge.
If not head gasket, I guess I will be pulling cam shaft unless you have different suggestion.

Cam bearing was put in wrong the hole doen't line up with the holes in the block . There will be 2 holes and if one is not lined up it will do just what your problem is. Might be able to drill it out with the cam out so you would not have to remove cam bearing.

Feeling down the oil drilling for the matching hole can be done with a brazing rod. If a hole is felt when turning slowly by hand, the bearing could still be in
wrong as the hole into the bearing is kinda 90 degrees from the top oil drilling. Jim

Not to ..muddy the waters.. the area that the oil comes up through may not require a special bolt. There may simply be enough space around the bolt for the oil to flow. I do not know the design of that engine but it could have a hole that feeds oil up near a head bolt at the block deck. Then the gasket could have an opening that allows oil to flow over to the bolt and push up around the outside of it. And in the case of your engine it looks like the rocker arm bolts are long and are also cylinder head bolts. So that layout would allow the design I explained to get oil to the rockers. See link. In an engine with this type of a design if it was assembled with copious amounts of sealer on the head bolts it could cause the valve train to be starved from lubrication.
Edit to add: BTW, cdale welcome to YT!
CNHI C 175 cyl. head parts diagram


This post was edited by used red MN on 12/06/2021 at 11:47 am.

Do not take one more screw out of that motor until
you contact the machine shop and get their input. If
you mess with it, you release them from all liability.
Maybe they will help, maybe they will not. But at
least give them a chance. But if this is one of those
cases where the motor sat around for six months
before being installed, you may be stuck doing the
work yourself.

Thanks for your input. That is where I am going today. To the machine shop to get their input/opinion. The head gasket was installed correctly. It appears, or I am guessing that the cam bearing is either not installed correctly or it spun during the couple of minutes we had the engine running.

You are correct on how the oil gets to the head. At least 2 of the valve brackets are hollow to accommodate the bolt and oil passage from the block. All 5 bolts were solid. Problem appears to be with the cam bearing.