Help! No oil pressure! 4.6 V8

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rich112
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Help! No oil pressure! 4.6 V8

Post by rich112 »

Just noticed my V8 has decided to have no oil pressure... :shock:

No apparent reason. Had it 2 days ago.

So could this be a stuck pressure release valve?

Can I get at that without taking the lump out or taking too much off the motor? I have good access to the front.

This is what I have:
The attachment 20210710_171543 (Medium).jpg is no longer available
20210710_171543 (Medium).jpg
20210710_171620 (Medium).jpg



rich112
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Re: Help! No oil pressure! 4.6 V8

Post by rich112 »

some more pics
Attachments
20210710_171632 (Medium).jpg
20210710_171708 (Medium).jpg

rich112
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Re: Help! No oil pressure! 4.6 V8

Post by rich112 »

So I dropped the oil, (black and smelly) and took off the oil pump cover.

The surface doesn't look good. :cry:

I don't know if the relief valve piston is in the right place?
20210710_182901 (Medium).jpg
20210710_182908 (Medium).jpg
20210710_183000 (Medium).jpg

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Re: Help! No oil pressure! 4.6 V8

Post by rich112 »

And another pic
20210710_183025 (Medium).jpg

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Re: Help! No oil pressure! 4.6 V8

Post by stevieturbo »

rich112 wrote:
Sat Jul 10, 2021 5:56 pm
So I dropped the oil, (black and smelly) and took off the oil pump cover.

The surface doesn't look good. :cry:

I don't know if the relief valve piston is in the right place?

20210710_182901 (Medium).jpg20210710_182908 (Medium).jpg20210710_183000 (Medium).jpg
Undo the big bolt on the left and pull out the spring and plunger, which should be moving freely.

Also verify whatever you are using as a gauge is working correctly. Wear and scoring would be typical and not a reason for "no" oil pressure.
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Re: Help! No oil pressure! 4.6 V8

Post by ChrisJC »

The wearing and scoring marks are normal.

But, do you get oil pressure if you rev it up?

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rich112
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Re: Help! No oil pressure! 4.6 V8

Post by rich112 »

ChrisJC wrote:
Sat Jul 10, 2021 8:14 pm
The wearing and scoring marks are normal.

But, do you get oil pressure if you rev it up?

Chris.
No sign of oil pressure. I didn't want to rev the motor past 2k.

The gauge was working fine.

The motor sounds noisy so defo lacking pressure.

I'll check the valve for free movement.

I can easily clean up the cover plate and put in some uprated pump gears and then see how it runs.

I might pop the sump off to check for metal in the pan.

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Re: Help! No oil pressure! 4.6 V8

Post by Ian Anderson »

Do you have oil? Was there a catastrophic leak? Sump plug come out?

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Re: Help! No oil pressure! 4.6 V8

Post by GDCobra »

Make sure you pack the pump with Vaseline when you re-assemble or you’ll struggle to prime it

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Re: Help! No oil pressure! 4.6 V8

Post by rich112 »

Ian Anderson wrote:
Sat Jul 10, 2021 8:28 pm
Do you have oil? Was there a catastrophic leak? Sump plug come out?

Ian
No loss of oil at all.

I drained 4-5 litres out of the sump.

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Re: Help! No oil pressure! 4.6 V8

Post by DaveEFI »

rich112 wrote:
Sat Jul 10, 2021 9:19 pm
Ian Anderson wrote:
Sat Jul 10, 2021 8:28 pm
Do you have oil? Was there a catastrophic leak? Sump plug come out?

Ian
No loss of oil at all.

I drained 4-5 litres out of the sump.
Was the low oil pressure light on as well as the gauge reading low?
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Re: Help! No oil pressure! 4.6 V8

Post by rich112 »

DaveEFI wrote:
Sat Jul 10, 2021 10:32 pm
rich112 wrote:
Sat Jul 10, 2021 9:19 pm
Ian Anderson wrote:
Sat Jul 10, 2021 8:28 pm
Do you have oil? Was there a catastrophic leak? Sump plug come out?

Ian
No loss of oil at all.

I drained 4-5 litres out of the sump.
Was the low oil pressure light on as well as the gauge reading low?
Yep. Sadly, I think it's probably spun a bearing. I'll take the sump off and see if I can check for metal and a lose big end... The pressure loss was not gradual.

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Re: Help! No oil pressure! 4.6 V8

Post by Ian Anderson »

Check oil pick up bolts are tight and gasket intact or it will suck air.

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Re: Help! No oil pressure! 4.6 V8

Post by scudderfish »

Ian Anderson wrote:
Sun Jul 11, 2021 6:45 am
Check oil pick up bolts are tight and gasket intact or it will suck air.

Ian
Just what I was about to post as it happened to me. However, I didn't lose all pressure immediately, that would probably need the oil pick up to fall off into the sump.

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Re: Help! No oil pressure! 4.6 V8

Post by DaveEFI »

I'd have thought if a bearing had failed enough to drop the oil pressure to zero, you'd hear it knocking?
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