7.3l loosing oil psi in head no visual leaks

1996 Views 9 Replies 2 Participants Last post by 417GreaseMonkeys, Nov 22, 2021

417GreaseMonkeys

Discussion Starter · Nov 3, 2021

I've got a 2000 f350 7.3l.
Initial issue it would only start when cold once it warmed up it would only crank, wouldn't start
Solution: replaced all injector o rings and retorque injector hold down plate bolts. Issue is still there. When it starts up while cold I'm getting 700-1000psi. When I shut the motor off it almost instantly looses all psi. And it makes a gurgling sound. I decided to hook the air compressor up to the oil rail and shoot pressure theres nothing leaking air up top but all I hear is gurgling when pushing air like it's just going right through it When I let off the air it instantly looses all pressure.
I've also replaced ipr with Motorcraft. If someone can help me out with this, that would be great.

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klhansen

· #2 · Nov 3, 2021

When you shut the engine off, the pressure will pretty much instantly bleed off thru the IPR, which opens when power is removed from it. That's the way it's supposed to work. If you've isolated the oil rails from the IPR/HPOP, and still have a leak, then check your injector o-rings again.
Does it start and run when cold or hot? If so, you're done. If it doesn't start when hot, you may have torn an injector o-ring on install. It could be leaking into the fuel rail or out into the valve cover area.

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417GreaseMonkeys

Discussion Starter · #3 · Nov 3, 2021

klhansen said:
When you shut the engine off, the pressure will pretty much instantly bleed off thru the IPR, which opens when power is removed from it. That's the way it's supposed to work. If you've isolated the oil rails from the IPR/HPOP, and still have a leak, then check your injector o-rings again.
Does it start and run when cold or hot? If so, you're done. If it doesn't start when hot, you may have torn an injector o-ring on install. It could be leaking into the fuel rail or out into the valve cover area.

Yeah my dumb a$$ forgot to undo hpop lines and plug the rail lol i shot 150psi into both heads neither of them leaked. And it starts up instantly when the temp gauge is below the halfway mark and oil psi is steady. When it gets to half way it will only crank and my oil gauge takes a minute to go up once it goes up its irratic and does not stay in one spot and will not start. Will a lpop be a culprit?

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417GreaseMonkeys

Discussion Starter · #4 · Nov 3, 2021

Now when I get to the halfway mark on the temp and I shut it off and try to restart the oil dummy gauge does not go up at all hpop resovour is full.

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417GreaseMonkeys

Discussion Starter · #5 · Nov 3, 2021

417GreaseMonkeys said:
Now when I get to the halfway mark on the temp and I shut it off and try to restart the oil dummy gauge does not go up at all hpop resovour is full.

And it will not start. It'll idle and drive at a warm temperature just fine but if I'm going down the hwy push the clutch in to slow down it will die If I pop the clutch it'll start back up and run until I have to push the clutch in again and it'll die when the rpms go down. When I turn it off I have to wait a couple hours before it'll start again.

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klhansen

· #6 · Nov 3, 2021

You may have an issue with oil supply if the oil pressure gauge drops. It's run by a switch on the top of the HPOP reservoir and cuts out at ~7 psi. Could be a problem with the oil pickup tube. If it's cracked, then it'll suck air. You can check for that by overfilling the crankcase with oil and jacking the rear end of the truck up about 3 ft. But first you should check the oil level.

You said you replaced the IPR, so that shouldn't be an issue. They'll sometimes be intermittent, bad when hot and work again after the coil cools off.

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417GreaseMonkeys

Discussion Starter · #7 · Nov 3, 2021

klhansen said:
You may have an issue with oil supply if the oil pressure gauge drops. It's run by a switch on the top of the HPOP reservoir and cuts out at ~7 psi. Could be a problem with the oil pickup tube. If it's cracked, then it'll suck air. You can check for that by overfilling the crankcase with oil and jacking the rear end of the truck up about 3 ft. But first you should check the oil level.
You said you replaced the IPR, so that shouldn't be an issue. They'll sometimes be intermittent, bad when hot and work again after the coil cools off.

Forgot to mention I just did an oil change on it also to rule out the possibility of the oil being too thin or an oil filter being clogged. So if the tube is Cracked what would happen if I overfill the crank case and jacked it up 3 feet in the back? Well **** if I'm not getting 7psi at the top them there's most definitely an issue with the oil delivery to the hpop?

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klhansen

· #8 · Nov 4, 2021

Jacking up the rear of the truck with more oil submerges the pickup tube in oil, so no air gets in.
It's possible that your LPOP steel rotors have worn into the front cover of the engine. That's only one of the things that would reduce performance of the LPOP. But there's also a possibility of the relief valve in the oil filter mount being loose and not letting pressure build up. That's a lot cheaper than having to replace the front cover, which requires jerking the engine out and pullling the pan to get the front cover off.

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417GreaseMonkeys

Discussion Starter · #9 · Nov 5, 2021

I've got a few injectors squirting out of the small hole on the back of a few of my injectors. If I remember right that means oil is leaking at the poppet? With having a few would that cause my issue?

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417GreaseMonkeys

Discussion Starter · #10 · Nov 22, 2021

Solved!
It was the hpop.

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