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Lost oil Pressure

Mackman

Mackman

FBBO Gold Member
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Fresh build of a 500 stroker this spring, new Melling standard pressure and volume oil pump. Before firing the motor the first time, I pre-lubed with a drill motor, and was sort of suprised at how long it took to bring up oil pressure. That was 1,000 miles ago. Oil pressure was running 45 lbs at start-up and cruising speed. Recently it started acting like it was running out of fuel when I got on it, so started looking for issues. Swapped carbs, changed fuel filter, no difference. Today I pulled the fuel pump, and found the pushrod was wore down 0.140in. I replaced the pushrod with one I had, and changed the oil and filter. On start-up, no oil pressure and plenty of valve train noise. I pulled the oil filter, and it had no oil in it. Replaced it with a NAPA 1515, and still no oil pressure. What am I missing?
 
Could be some of the lost pushrod metal got lodged in the oil pump. I usually fill the filter but it should pick up on its own.
 
If you left filter off for a few hours may have lost oil to seal pump. It happened to me, pulled pump put some thick oil it and that fixed it. Was told you could pull oil sender and fill through there. if you have and other things like a bulb pump.
:lol:
winner.JPG
 
Last edited:
The hex portion on my oil/dist. drive snapped after doing a oil change, how's yours? Don't ask me how it happened, because I have no idea? And it still is the original oil pump as well. It was the original with 90+K miles on it. Good Luck
 
Check for broken drive shaft
Remove pressure valve form pump and look for
debris. Can be done on the car without removing pump.
Prime the pump again to test it so you don’t run the new engine with zero pressure.
 
Mackman said:
Fresh build of a 500 stroker this spring, new Melling standard pressure and volume oil pump. Before firing the motor the first time, I pre-lubed with a drill motor, and was sort of suprised at how long it took to bring up oil pressure. That was 1,000 miles ago. Oil pressure was running 45 lbs at start-up and cruising speed. Recently it started acting like it was running out of fuel when I got on it, so started looking for issues. Swapped carbs, changed fuel filter, no difference. Today I pulled the fuel pump, and found the pushrod was wore down 0.140in. I replaced the pushrod with one I had, and changed the oil and filter. On start-up, no oil pressure and plenty of valve train noise. I pulled the oil filter, and it had no oil in it. Replaced it with a NAPA 1515, and still no oil pressure. What am I missing?
Click to expand...
A good oil pump for sure.
 
If all else fails make sure a lifter didn't come out because that will make you lose oil pressure. Pull the valve covers to make sure all pushrods are seated.
 
I pulled the oil filter, put as much oil as I could in it, tried it, still no pressure. I pulled the oil pump, filled the filter and pump with 20w-50, re-installed the pump, oil pressure back to 50. Thanks for the responses.
 
The 1st filter I tried was a Fram.
 
Mackman said:
I pulled the oil filter, put as much oil as I could in it, tried it, still no pressure. I pulled the oil pump, filled the filter and pump with 20w-50, re-installed the pump, oil pressure back to 50. Thanks for the responses.
Click to expand...

These pumps need some oil inside to seal the rotors against the housing and create vacuum.
As others mentioned, if it stands still for quite some time with no oil filter the oil would drain out of the pump and will not be able to self-prime anymore.
Good you found it and had no other damage to your engine!
 
It’s unlikely you fuel pump pushrod woes are over.
When the rod starts wearing out, it usually negatively impacts the pump lobe on the cam.

You could have just reprimed the oil pump instead of taking it off.
 
PRHeads said:
It’s unlikely you fuel pump pushrod woes are over.
When the rod starts wearing out, it usually negatively impacts the pump lobe on the cam.

You could have just reprimed the oil pump instead of taking it off.
Click to expand...
How would you reprime pump? Like to hear other ideas. Didn't have priming shaft available. Start engine the no oil pressure in 30 seconds I shut it down. I suggested with bulb pump prime through oil pressure switch holes, that the only way I can think of. When it happened to me I think less a act first:rolleyes: pulled pump as he did . Those bulb pumps are handy to have.
 
69a100 said:
Do not, ever, EVER use those piece's of **** filters!
Click to expand...

I never used them, came across them though but now you make me wonder what is the issue with them?

PRHeads said:
It’s unlikely you fuel pump pushrod woes are over.
When the rod starts wearing out, it usually negatively impacts the pump lobe on the cam.

You could have just reprimed the oil pump instead of taking it off.
Click to expand...

My pushrod ran to crap and was way short of specs, the cam (Old Hughes engines grind) did survive.
Just put a new rod in and worked fine. Lobe had no damage at all.
 
Before firing the motor the first time, I pre-lubed with a drill motor, and was sort of suprised at how long it took to bring up oil pressure.
Click to expand...

I figured he had access to a priming tool.
 
Wietse said:
These pumps need some oil inside to seal the rotors against the housing and create vacuum.
As others mentioned, if it stands still for quite some time with no oil filter the oil would drain out of the pump and will not be able to self-prime anymore.
Good you found it and had no other damage to your engine!
Click to expand...
I don't claim to have decades of experience but in all my years, I have never had this happen. I've had cars sit for months and never had a problem with them losing oil pressure.
 
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