No Oil Pressure on 7.3 Idi

[Jim993]

There are two 1/8 npt plugs in the main oil gallery, driver side, the rear one is often used for oil to the turbo if one is added (like my truck). the other is further forward on the same horizontal line from the rear one. Both plugs provide access to the main oil gallery which should be pressurized in normal operation. In my case, the rear plug is used for oil to the Banks turbo, the front is plumbed with 1/8 copper tube to the relocated oil pressure sender unit which also has a mechanical gauge so I can check real oil pressure when in doubt.

 

[Paulalanrade]

It sounds like you're testing it right, I second the port is probably plugged internally.

Try this other port here, see if you get different results. I bet you have oil pressure. With only 3psi your engine would have been toast after a few days of driving.

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Well. Bad news, I tried this port here that everyone’s been talking about, granted mine uses a square head. When I unthreaded it, a little oil came out, and I threaded in my mechanical gauge… started her up, no oil pressure. I ran it for a total of 20 seconds, and idled it up too. (I don’t have the radiator hooked up right now so I didn’t run it longer)

 

[Nero]

Yowch, sorry to hear about that. I'd be pulling er apart to see what the heck is going on and also cjeck for bearing damage.

Kind of order of operation I would go is check to see if the pickup tube screen is plugged, then pull the oil pump off and check it out.

I would also pull #1 and #4 rod caps and check the bearings.

 

[IDIBRONCO]

It takes a 9/32" square socket to remove it IIRC.

granted mine uses a square head.

Perfectly normal, perfectly normal. Nero's picture shows a square plug as well. It's a little bit on the damaged side so it doesn't look quite square.

 

[Jesus Freak]

If it doesn't have oil pressure......shouldn't lifters be tapping?

 

[Nero]

If it doesn't have oil pressure......shouldn't lifters be tapping?

Also the bearings should have spun by now. Not a lot makes sense, but before catastrophic failire occurs, take it apart and fixit

 

[asmith]

If it doesn't have oil pressure......shouldn't lifters be tapping?

This was my thought too. If he drove it that far with no oil pressure that engine should be screaming. Lifters should be bad, bearing should be welded to the crank, all sorts of bad things. All that said I have heard of these engines, and the 300 straight 6 going for a long time with very low oil pressure or low oil levels, so maybe it will be ok. I for one, am intrigued and cant wait for the teardown and see what the problem is.

 

[Jesus Freak]

This was my thought too. If he drove it that far with no oil pressure that engine should be screaming. Lifters should be bad, bearing should be welded to the crank, all sorts of bad things. All that said I have heard of these engines, and the 300 straight 6 going for a long time with very low oil pressure or low oil levels, so maybe it will be ok. I for one, am intrigued and cant wait for the teardown and see what the problem is.

Definitely a fine start to a mystery novel......let us hope together that he allows us the satisfaction of knowing how it ends......unlike others who disapear without a trace.....thus creating more mystery and intrigue......

 

[IDIBRONCO]

If it doesn't have oil pressure.

If he drove it that far with no oil pressure

He doesn't have 0 oil pressure. It will go to 2-3PSI on his gauge. He has next to 0 oil pressure. There is still a possibility of minimal internal damage.

 

[Paulalanrade]

There was in fact 0 oil pressure the most recent time I tested after putting the oil cooler back together and back on the engine. (This was from when I said I ran it for about 20 seconds total)

And yes, I did try multiple ports to test.

In the process of getting ready to pull the engine, I took off the new oil filter I put on after redoing the oil cooler… yikes, the filter was bone dry.


The ol Idi will be coming out tomorrow, I have everything unhooked from the engine and the hood off, now I just need to chain it up to some pallet forks on the skidloader, and throw it on a stand. I’m hopping it’s okay

 

[Paulalanrade]

Mystery Solved, kind of. I don’t know how, or why, but there is a papery material that was inside of the oil pan, and had clogged the pickup tube too.

What’s weird is I’ve never been inside this engine, I’ve never somehow shoved paper towels inside of it.

Could it have been from years back? I don’t know. Could the oil filter have somehow gave out and clogged it, not sure.

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[Nero]

Holy burrito that's a clog! Glad it was an easy find!

 

[onetonjohn]

Unclog it and run it???? Or is that a terrible idea?

 

[Nero]

Unclog it and run it???? Or is that a terrible idea?

I would at least check one rod bearing while its apart.... If its fine... Then maybe

 

[ihc1470]

The 6.9 I ran years ago went through lots of oil. There would be times I would forget to check it and the lifters would collapse and you would know it was out of oil. I always carried a couple of gallons with me. Fill it up and withen a couple of minutes the lifters would quite down.

Did you find any metal in the pan or do any of the rods look like they got hot? If not I would do as Nero suggest and check one or two rods and maybe a main. If they look good I would probably take a chance. Would not really be that hard to run it on a test stand before installing back into truck and see what happens. You could check it for oil pressure and leaks. Running if for 15 minutes or so should give a pretty good idea if it survived or not.