75 lbs. oil pressure to ZERO in 10 seconds. WTF?

Mark Barnes

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Relief valve could be hung open or a dozen other possible problems... A lifter out of it's bore, oil pump found a way to suck air, oil pump drive shaft sheared...

In your post you say "Intermediate shaft, no issue, gears just like brand new." did you actually pull the shaft & inspect it? Or looked & saw the gears look good? Cause twice I've seen the drive hex get sheared off...

Have you tried spinning the oil pump with a priming tool?
I did pull the shaft and inspect it, it's in perfect condition. I stuck the priming shaft down there and spun it....nothing. Priming before break in I had to hold the drill with 2 hands and it still tried to twist my wrists.
 

Mark Barnes

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I hope it is just a stuck relief valve, but........

To check the pump p/up, remove the pump. Blow compressed air into the p/up passage in the block. If you hear air hissing, p/up has broken. If you here gurgling [ oil ], it indicates p/up is ok.
I like this test idea. Thanks!
 

gtxrt

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I like this test idea. Thanks!
why take the pump off ? just take the spring out and put a pencil like magnet in there and free and take the relieve valve out, clean and check for burrs. now you either found the problem or eliminate one problem it could be.
 

Mark Barnes

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why take the pump off ? just take the spring out and put a pencil like magnet in there and free and take the relieve valve out, clean and check for burrs. now you either found the problem or eliminate one problem it could be.
That what I'm gonna do!
 

gtxrt

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That what I'm gonna do!
a few ounces of oil will come out and maybe any debris so put a pan underneath. then after together i would prime the pump again and you will know for sure if there is resistance with the drill.
 

Tony Tee

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I saw a video on YouTube that disassembled a brand new hv oil pump. Only to find dirt and metal bits from the manufacturing process. So I guess I'm taking mine back off to check for foreign objects.
 

Roger63

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I had the very same problem, it was my pickup tube was to short. It had a straight tube and it was incorrect. 440 source sells the correct tube
 

4406bbl

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I saw a video on YouTube that disassembled a brand new hv oil pump. Only to find dirt and metal bits from the manufacturing process. So I guess I'm taking mine back off to check for foreign objects.
This, and deburr the pump cover and rotors. They are really rough in that area. The relief valve should fall in and out on its own, some need a little polish work.
 

Mopar2u

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In my opinion, when you lost oil pressure due to a hard brake - That is when a lifter collapsed (Even for a moment), allowed a pushrod to pop out, and now a lifter is no longer in its bore. (Had this happen to me during a hard acceleration once). Did most of the oil pump suggestions here, nothing ever recovered the pressure. Wish I had just taken the valve covers off, looking for the one loose rocker arm back then. It wasn't until I started taking the motor apart (figuring I had wiped out the bearings) that I found the bent pushrod and lifter just lying there in the valley!
 

RemCharger

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SFT camshaft/ lifters. If one of them collapses I have WAAAY bigger problems that no oil pressure!

In my opinion, when you lost oil pressure due to a hard brake - That is when a lifter collapsed (Even for a moment), allowed a pushrod to pop out, and now a lifter is no longer in its bore. (Had this happen to me during a hard acceleration once). Did most of the oil pump suggestions here, nothing ever recovered the pressure. Wish I had just taken the valve covers off, looking for the one loose rocker arm back then. It wasn't until I started taking the motor apart (figuring I had wiped out the bearings) that I found the bent pushrod and lifter just lying there in the valley!
 

Mopar2u

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Good point on the solid lifter cam setup! I missed that - My mistake.

- In my case, it was a stock lifter/valvetrain setup, and I didn't realize if a lifter was not present, neither was the oil pressure. Guess I'll leave my reply in case it helps someone else. Good luck and I hope you get this figured out soon.
 

1 Wild R/T

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Just cause your running solids doesn't mean you can't have a lifter pop out.... Buddy of mine had exactly that happen... Turned out his pushrods were a little to long & at full lift the pushrod cup would contact the rocker body... Eventually a pushrod popped out & the lifter popped almost immediately..
 

RemCharger

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But you would know something is up with that serious of a miss.
7cyls has a different feel than 8.
 

1 Wild R/T

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But you would know something is up with that serious of a miss.
7cyls has a different feel than 8.
Per the original post since losing pressure the engine has run less than thirty seconds & hasn't been driven/put under a load.... You'd be shocked how many engines I've worked on with a dead hole that the owner had no idea... I'm sure the O/P would notice but not necessarily in the first thirty seconds with the engine not under load & with his attention focused on his loss of oil pressure..
 

Mark Barnes

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Just cause your running solids doesn't mean you can't have a lifter pop out.... Buddy of mine had exactly that happen... Turned out his pushrods were a little to long & at full lift the pushrod cup would contact the rocker body... Eventually a pushrod popped out & the lifter popped almost immediately..
That sucks right there!
Just cause your running solids doesn't mean you can't have a lifter pop out.... Buddy of mine had exactly that happen... Turned out his pushrods were a little to long & at full lift the pushrod cup would contact the rocker body... Eventually a pushrod popped out & the lifter popped almost immediately..
Agreed, and that does suck about your buddy. My motor never missed a beat, and no noise either. I stuck the priming rod down there, and spun it with no resistance. Also couldn't see any oil move in the oil line to the gauge. I think the problems down in the bottom, and I'm gonna be back in there in about an hour. I'll post results.
 

1 Wild R/T

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That sucks right there!

Agreed, and that does suck about your buddy. My motor never missed a beat, and no noise either. I stuck the priming rod down there, and spun it with no resistance. Also couldn't see any oil move in the oil line to the gauge. I think the problems down in the bottom, and I'm gonna be back in there in about an hour. I'll post results.
He got lucky, no damage & didn't cost him anything besides needing shorter pushrods... Oh, and the tip for the tow truck driver.. AAA got the tow bill but since it was close to 100 miles he at least bought the guy lunch
 

66Satellite47

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My 1st drag motor, 426W, had a rocker back off, lost oil pressure, lifter out. I didn't notice, stalled 3 times on the return road before the motor locked up. OOPs. Got it home, pulled the motor, chiseled the rod bearings off the crank. Put the crank in the dumpster.
 

gtxrt

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what ever cause it just needs to follow steps, easy ones first relieve valve or taking valve cover off, already did the right thing taking dist out and checking and trying to prime engine, the next step hope not, taking oil pan off.
 

PRHeads

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He said he was planning on changing the oil anyway.

If the relief valve isn’t stuck, my next thing would be to drain the oil......... then fish around thru the drain hole with a small magnet to see if the pick up is laying in the pan.
 
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