Does anyone know if the check valve between the LPOP and the upper reservoir is accessible and replaceable when accessing the LPOP?

If not, what's involved to get at the darn check valve.

It's been letting the upper reservoir leak down which makes starting a real bear. I've been putting up with it for years but it's getting really annoying.

Thanks

 

It comes out the top of the block.
Look down at the HPOP res, down the right side all the way to the top edge of the block, right close to the front cover. You'll see an internal drive pipe plug. Remove that plug and there's a spring and ball in there.

 

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Is the drive pipe plug accessible or do I need to remove the manifolds, etc as the picture suggests?

 

just look down to the side of the res, you'll see it down there.

 

The OP's truck is a 94.5.
My wag is he means the DA valve in the front cover.
Common issue is the valve will unthread itself and fall out.

The early PSD has a check valve in the pump itself.


An old cut and paste.
Front Cover
A deareation valve was inserted in the front cover beginning with engine serial number 201681 through engine serial number 375549 .
The front cover was redesigned starting with engine serial number 375549 to help keep the oil pump primed for initial start up.
To accommodate this change, the pump inlet port was rotated 90° which moved the pickup tube from the left to the right.
The front oil cooler header gasket was also redesigned because of the change to the front cover.
The front cover has been modified for the updated reservoir to front cover gasket and passages have been cast and drilled into the front cover to incorporate the standpipe.
The engine serial number that the standpipe was incorporated is 201681 .
Oil Reservoir for the High Pressure Pump

As of engine serial number 187100 the reservoir has been cast and drilled to include the standpipe and is drilled, tapped, and spotfaced to use both a straight thread, o-ring sealed engine oil pressure sensor and inspection plug as sealing enhancements.


Bill