4.0 OHV oil pump priming tool?

[Dunk67]

Almost done rebuilding a 4.0 OHV. Does anyone make an oil pump priming tool for these? If not how do you prime the oil system? I'd rather not just crank with plugs out until it gets pressure. The oil pump driveshaft has goofy splined ends instead of a typical hex drive.

 

[RonD]

No, as far as I know, no one makes a tool for that

You can get and disassemble a 4.0l OHV cam synchro from wrecking yard
Gear is held to shaft with roll pin, then at the top remove the "signal ring" and shaft will drop out
But needs a 1/2" chuck on the drill, 3/8" won't work


Cranking the engine over without starting is a better method as oil gets into all the parts as it turns vs static which gets oil into passages but doesn't spread it around parts
Oils main function in any engine is to cool the parts, lubrication and hydraulic pressure are needed but secondary to cooling
Since engine is not hot, so cooling is not needed, manual lubrication(static) really doesn't help anything

Old school "Primed the oil system" because oil pumps often were not great at self priming, really don't have that issue any more with better machining of the oil pump gears
But won't hurt anything to do it Old School

 

[Dunk67]

On the oil pump drive. The seal on mine seems to be more of a square molded piece of plastic, like a bushing. It does not fit snug in the block, very loose and surely will leak. Maybe it's just a hardened oring.

I got a FelPro 74061 distributor mounting oring for Ford V6 which lists applications 4.0 OHV VIN X 1991-1995, as well as 3.0 1991-1998 and 3.8 1990-1995. This oring seems smalled thickness than what's in there now, unless it is intended to sit at the very top under the flange where there is a small groove, though the oring doesn't sit down it it nicely since it's a very shallow groove.

Am I supposed to remove and replace the existing part that seems thicker? Or Slide this smaller oring to the top and let the hold down keep it sealed to the block? Or do I need a different oring to replace the hardened part?

 

[Shran]

That is a hardened O ring, remove it and replace it with your new one.

Lube it up with vaseline when you install it... often I have to give the top of that a soft tap with a mallet to get it seated.

 

[Dunk67]

Thanks. New oring looked slight thinner but definitely squeezed in a bit and is sealing.