Oil Pressure 1934 Hudson LT Straight 8 ( 254 )

Good afternoon 

I need some advice. I´m working on my engine block ( 1934 straight 8,  254 ) and it seems that the oil pump have two exterior lines with pressure, one line goes to the relief valve at the back were the oil sensor is bolted,  and the other one goes to the front of the block were is a L connection bolted that supply oil to an open hole in the front of the block who give oil/ lubrification to the front distribution pinions. I cant find any other oil pressure line in the block.

The connecting rods are splash lubrification with no oil pressure, but checking the camshaft and the crankshaft bearing it seems that both are working with splash system too.

The crankshaft  main bearings has a hole that is not connected to any oil pressure line, in the other side of the hole is open to the interior of the block to take some oil by splash / gravity.

The same happens with the camshaft bearings. No oil pressure at all, just a hole conected to the interior of the block.

So it seems that the oil pump only works to give oil with pressure to the distribution pinions, It seems very rare that there is no oil pressure line at the crank main bearings , neither at the camshaft bearings. 

Also is very rare that the oil pressure line who goes from the oil pump to the front of the engine that ends in an open hole. Must be very difficult mantain any good oil pressure in the line to switch off the bulb who send the signal to the oil warning light on dashboard when the line ends in an open hole.

I know that Packards has a big hole at the front of the oil pressure line for the distribution lubrification, but the hole is plugged with a cap, and the cap has two small holes ( buttefly hole ) who let the oil goes to the pinions. In the Hudson the hole is not that big like the Packards, but is big in any way to keep any good pressure in the oil pressure line.

Thank you very much in advance for any explanation about the oil pressure / lubrification of this type of engines



  • tombiatombia Posts: 188Member
    I think that with some investigation you will find that the oil pumps  oil from lower pan to upper pan
     at around 3psi, and thats it 
  • GeoffGeoff Posts: 4,606Senior Contributor
    Correct.   There is no pressure feed directly to any bearings.   The fitting at the back of the block is simply a switch to the oil light, to indicate that the  pump is working.  All the pump does i circulate the oil form the  sump to the front and back of the engine, where it is splash fed to all components.    
    If you're stuck in a hole, stop digging.
  • CarltonCarlton Posts: 14Member
    Thank you very much for the replies. 
  • DonaldDonald Posts: 49Member
    If the  oil line that goes to the oil pressure switch just make the sender work why does the line T off and go up into the block.  It must do something else.  Does it raise the oil high enough that gravity can then let it flow down through weep holes and back to the pan.?
  • GeoffGeoff Posts: 4,606Senior Contributor
    Teh pump has two outlet pipes, one goes to the front of the motor, the other to the pressure switch.   The oil flows through the pressure switch and into the rear of the block, into No. 8 trough.  
    If you're stuck in a hole, stop digging.
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