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Had my engine rebuilt last year by a reputible local machine shop. I've probably run it 20 hrs and I had a carb issue (stuck throttle). That got me to looking at other things. Popped the valve cover and the top of the engine is bone dry. Good oil pressure at the gauge (on oil filter housing) so I know the pump is making good pressure, but its not getting upstairs. The line running outside the engine block to carry oil up to the head is clear (ran wire through it and blew air trough it).

Any ideas as to what is going on here ? Any thoughts would be really helpful. I'm really worried about the $$ and time invested here.

Thanks for your help!
 

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Do you have any technical manuals for this tractor? I’m not familiar with that engine, but it sounds like you are on the right track. Do you know how the oiling circuit works? In other words, how the oil is to get to the valves? Does the external oil line go right to the rocker shaft?
 

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Yes, the external oil line connects to the rocker shaft. I would take the fittings off on each end of the oil line. On my MC it is not high pressure by any means, so you could run it a little without that line in place just to see if oil is getting to the lower fitting. If not, there are passages cast into the block below that. Also there is a strainer on the oil pump. I had some issues with mine, and it had blockage just below the oil line in that fitting. Good luck, let us know what you find.
 

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Remove the oil supply line and fitting(#5) at the back of the block. Run the engine for a bit. Oil should flow out of threaded hole. If so, install a gauge in hole to check pressure.
Don't hold me to this, but I believe oil pressure is about 12-15 psi. :unknown:

If oil flows from threaded hole, check condition of 90% fitting(#3). It may be restricted. Also, check oil passage at cylinder head for internal restriction/obstruction.

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