7.3l loosing oil psi in head no visual leaks

1974 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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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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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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