8BA first startup no oil pressure

D

dsiddons

Member
Primed and started a freshly rebuilt 8ba today.. No oil pressure. Used two different gauges.. Whats wrong??? Oil pump relief valve stuck open? Is it possible to install the oil pump plunger and spring incorrectly?? Other wise ran like a top..
 
dsiddons said:
Primed and started a freshly rebuilt 8ba today.. No oil pressure. Used two different gauges.. Whats wrong??? Oil pump relief valve stuck open? Is it possible to install the oil pump plunger and spring incorrectly?? Other wise ran like a top..
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Check to see if you forgot the galley plug behind the cam gear.
 
dsiddons said:
Is that behind the timing cover? No leaks noted..
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Yep, you won't notice a leak unless you pull the cover...

Are you using the stock fuel pump? If, by chance, someone removed the pump rod bushing when running an electric pump, pressure would be very low/nonexistant.
 
It will just leak back to the pan. But the oil following the path of least resistance will not go through the bearings as intended. It seems that forgetting to reinstall these plugs is a rather common mistake.
 
dsiddons said:
Primed and started a freshly rebuilt 8ba today.. No oil pressure. Used two different gauges.. Whats wrong??? Oil pump relief valve stuck open? Is it possible to install the oil pump plunger and spring incorrectly?? Other wise ran like a top..
Click to expand...
How did you prime the pump?
 
how did you prime your engine, as you've said??...there is oil in the pan??...how long since rebuild?...you using a mechanical gauge at the back of the block??....if newly rebuilt, did you have the rear oil passages drilled and plugged for full-flow filter setup??....if so, are you running that filter??....wouldn't start tearing into it 'til some questions are answered....Mike
 
We had the same issue. Pulled the pan and oil pump and poured oil into the pump, reassembled and we got pressure.
 
Ronnie said:
Tell us how you pre lubed the engine?
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Pre lubed? Assembly lube? or pre primed? Took out the plugs and ran thru with the starter while watching the oil pressure. At that time only got about 10psi. After first start it was at about 20psi. Should have been alot higher than that. So we swapped out gauges and tried again with 0psi.. Should I have primed it a different way?
 
To prime the pump all I did was take off the oil pressure sender gauge and screwed a stand pipe in the hole. Then injected about a half cup of oil in it. Screwed a mechanical gauge on top of the pipe and that was it. See picture showing stand pipe and gauge.
100_1993.jpg
 
oldford2 said:
To prime the pump all I did was take off the oil pressure sender gauge and screwed a stand pipe in the hole. Then injected about a half cup of oil in it. Screwed a mechanical gauge on top of the pipe and that was it. See picture showing stand pipe and gauge.
100_1993.jpg
Click to expand...

Thats where we had the oil pressure gauge set up also. Where does that half of cup of oil go? Thanks..
 
Not trying to sound like a butthead here, but you can answer a lot of your own questions if you study how the flathead oil system works. It is easy. Oil pump is driven off of gear at the rear of the cam shaft. Oil is pushed up vertically through block to the boss on the back of the block where the oil pressure sender is and where some oil is diverted to the oil filter, if one is installed. (On a stock oil filter, there is a restrictor fitting that only allows a portion of oil to be filtered then returned down to the pan.) From the boss, the oil goes horizontally back towards the center of the block to that tube that runs forward in the lifter valley. From that tube, there are three vertically down holes that distribute oil to the 3 cam bearings and the 3 main bearings. There is a hole at the back of the tube where the fuel pump rod rides on the cam lobe. If that hole is left open, poor or no oil pressure. At the front of the block behind the cam bearing, there is a hole with access to the front of the aforementioned tube. If that hole is left open, poor or no oil pressure. Otherwise, oil pressure is determined by wear of the cam and main bearings. Hope this helps.
 
This is a rare occurance but it happened to me. The gear on the back of the cam shaft is a press fit. Mine came loose and therefore, no oil pressure. I only found it by accident after trying everything I could think of to find out what was wrong. Had the gear drilled and pinned to avoid any further problems in that area.
 
I may have gone overboard on this priming thing, but I wanted to prime the whole motor and not just the pump before starting. I took a spare flathead filter can and welded the lid shut on it. Ran a hose from the can bottom hole to one of the oil holes in the back of the block. Fitted an air hose to the can side hole and filled the can with oil through the top hole. Applied about 20 pounds of air pressure to the can until the oil had been forced into the engine. Everything got primed including the bearings.
 
Your post says that you had 20 psi on first start, 10 psi on starter is ok also. Then you swapped gauges and had 0 psi. Not knowing what was done to the engine new cam brgs oil pump etc 20 psi is not the end of the world. Was the crank ground? what are the clearances..Put the gauge back that had 20 psi and confirm.
 
Yanked the oil pump and it look fine. Plunger and spring in correctly. Pulled of timing cover and found galley plug missing.
 
Me and my dad are having the same problem with his fresh 8ba. We pulled the timing cover today and the plug is in place. What should we check next? It has a new melling high volume oil pump. Thanks
 
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