TO-35 Chasing Low Oil Pressure. Camshaft Bearings.

Hello.
I am chasing a low oil pressure condition on my TO-35. I replaced the main and rod bearings. Oil pressure still low when warm. I have the timing cover off and was going to remove the camshaft. The internet shows camshaft bearing available from multiple sources, but the shop manual says that "Camshaft journals ride directly in three machined bores in cylinder block". Can someone confirm if the camshaft has replaceable bearings or not before I get it further apart? I appreciate the experience.
 
The cam does run directly in the block, no bearings.

And there is a lot more to getting the cam out than pulling the front cover! I have never seen the cam bore wear enough to cause oil pressure problems.

When the rod and main bearings were replaced, were the crank journals measured? If the crank is worn out of specs it will not have good oil pressure.

But while the cover is off, inspect the governor carefully, they are a known trouble area.

Was the oil pump disassembled and inspected? The pumps are a weak point, should always be inspected, repaired or replaced whenever there is an oil pressure problem.

How low is the oil pressure? They are not known for having good hot idle pressure. If the gauge moves off the peg at slow hot idle, and comes to the edge of the green up to speed, and there is no knocking, it will be safe to run. Seen them run like that for years with no damage.
 
Thanks Steve for the reply.

If there are no serviceable bearings on the cam, then I won't go any deeper into it.

I reinspected the governor. It has spun around many times but seems to be in good order. I think I found the answer but the shaft coming off of the flying saucer disk is smooth, smaller diameter, and then back to bigger diameter and smooth again. From the pictures of a new one, that is normal. All the balls are in place. The entire compartment has a millimeter or so of sludge on it. It has been missing the Governor Compensating Spring for 20 years, I will replace that.

I did not measure the crank. The old bearings did not look too bad so I just put the new ones back in with hopes it would work. They all still "seem" tight. I rebuilt the oil pump last fall when I tried the first time (all rod bearings and front 2 main bearings). The oil pump rebuild did increase the oil pressure slightly.

So here is what it is doing.... It is my belly mowing tractor, I have been using it twice a month in the summer an hour at time for the last 20 years. After the bearings and oil pump rebuild, when you start it the oil pressure goes to 30 psi. When the water temp stabilizes at the top of the green water temp band, then the oil pressure is 10-15psi at mowing RPM. and barely any needle movement at idle. It has been getting steadily worse over the last 5 years or so such that I felt I should address it.

Should I safety wire the main bearing bolts? Whoever was in there 30 years ago did not, but I have the wire and pliers, so I figure I had might as well. I did not notice the holes last time I took it apart.
 
mvphoto55452.jpg
 
Carefully inspect the cage that contain the ball bearings of the governor for cracks. The common failure of the unit is the cage breaking and allowing the balls to descend into the gears where bad things happen.

When you inspected the main/rod bearings were they oversized? Where you're at it wouldn't be hard to drop the pan and plastigauge the bearing/crank clearance. I believe bearings are available in .001" oversize if you are dealing with an unground crank.

Heavier oil (15w-40 perhaps) could boost pressure a bit. What do you use?
 
Cam bearings are available form the after market Sealed Power Part # SH683S. How ever your block will need to be bored to accept the new cam bearings. This site shows the part # but out of stock.
 
The oil pump is the weak point in the lube system. The relief valve can stick open, the spring can "soften", etc and then there is normal wear and tear on the endplates. Unless you put the wrong size mains and/or rod bearings in, that"s where I"d advise you to look
 
I bought a pump rebuild kit and it didn't help. Think my problem was the wear in the pump cover since new bearing were within specs with plasti-gauge.
 
I replaced the crankshaft bearing shells in
my Standard engined FE35, built in the UK.
Stupidly I didnt measure them with a
micrometer first . The new ones were thinner
than the 60 year old originals ! The oil
pressure went from just OK to almost non
existent. It's nice to be able to buy parts
for such old machines but don't take them on
face value, check, measure and re check
everything.
 

The main bearings measured between two and three thousandths interpolated to twenty five thousandths. I am comfortable with that.

I think the problem is with the rod bearings. Two measured near six thousandths and two were over.

So it comes down to trying the .002 undersized rod bearings and leave the crank in the tractor. Or pulling the crankshaft out and grind and replace all the main and rod bearings.

Do you think it will work to install the .002 ones and it will work ok? Or is it so far wore that I need to do it the right way by removing the crankshaft?

The attached picture is from fourth rod bearing, you can see it didn't even really compress the material.

PS I had a more informative reply all typed out but it would not let me post it.
 

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