Saturday I replaced the distributor in my 1993 4.9 F150. More difficult than expected because of it being such a tight fit (both old and new). Removed all plugs, found TDC, and set the distributor pointed to #1 cylinder. Reconnected everything, verified the firing order. Started right up, but the oil pressure gauge shows no pressure. Shut the truck down immediately.

The sending unit is very close to the distributor and I certainly could have bumped it during the distributor install. I tried to check for voltage from it with a voltmeter yesterday and the voltmeter always read 0.0.

If I ground the wire to the sender and it pegs high, is that a valid test on the gauge? If that works, what is the best way to test the sending unit before I replace it?

And, is there a way to convert this over to a real gauge instead of the "idiot light" version?

 

The oil pump is driven off a shaft underneath the distributor. Is it possible you pulled this shaft out and did not replace it? Or it pulled out of the pump and then fell down into the oil pan?

 

Do not start it again until you get a proper answer to this. I don`t know enough about the 300 six to be sure but the oil pump may be driven by a shaft that engages in the distributer shaft. When the new dist went in the oil pump drive shaft may not be engaged so the oil pump may not be driven at all.
Like I say I don`t know, so hopefully someone who does will reply soon. Or maybe do a search and see what comes up.

 

The shaft came out with the distributor. I reinserted it into the new distributor and then when the distributor was installed, I looked into the hole and a metal rectangular bar with a hole was visible. I put the shaft into the hole. Was that correct?

 

The hole in the oil pump where the shaft goes should be hex-shaped.

 

Indeed it was, as was the shaft. Perhaps I should remove the distributor and verify that the shaft entered the hex hole, but I thought that it had.

 

Yeah I would say you need to pull the distributor again and have a look.

 

If you ground the wire, it actually should read about halfway as you don't have a real gauge, unless you or some PO converted it. If it does that, then your gauge is fine. Next I would pull the sender and then crank the engine by jumping the solenoid with the key off (so the motor won't start) and see if oil shoots out the hole.

 

Ok. I'll start there after work. Much appreciated. Reputation updated.

 

1. Ground the wire that attaches to the oil pressure sensor. If the needle does not move, the gauge is bad, replace the gauge, DONE. If the needle moves (roughly to halfway), the gauge is fine.

2. Remove sending unit. Cycle the engine with the solenoid and watch for oil to come out of the hole. If it does, replace the sending unit. If not, remove the distributor and check that the shaft is engaged.

 

Well the truck is at the mechanic's. Knowledgeable, trusted folks. Should know something in the morning.

 

On my 79 ford, when i pulled my distributor. My oil pump shaft came out and i ended up pulling the pan to re-install it.

 

I've a 2 ft long oil pump drive shaft used to prime engines after I've had them down, shouldn't be that hard to find. It used to be a NAPA or tool truck type item. You simply spin the shaft with a 3/8th drill to make sure you have pressure..........

 

If you didn't coat the drive shaft with grease before you put it in the new distributor, it can fall out as you slide the distributor into the block and fall out and end up in the oil pan instead of slipping into the oil pump.

 

Heartily agree with oldproudvet

If you're lucky, we used to use a piece of fuel line that fit over the oil pump drive and spin it with a drill too.

Make sure the shaft DOES have all the flat sides on it and the dist hole isn't spun rounded. Can it go in both ways?

Then again, if oil shoots out when you crank it, might be ok too?

I haven't looked at mine but I'd almost bet any parts store has a real gauge, or even a hrdware store for a few bucks, just screw it into the sending unit hole just to see..or get a pipe fitting tee and run them both, gauge under the hood and stock dash gauge for backup.

Heck, I may even look into that just for fun and minor bragging rights.
Give me something else to look at when I have to hood open.

I just dont like the thin plastic tubing I've seen with oil gauges running near hot stuff and chafing in 10 different places.