Loss of oil prime

I'm having some weird oiling problems since I reassembled my 200 with the forged pistons. If I let the car sit for a few hours, the engine will loose it's oil prime and I will get some light tapping on acceleration. I suspect that the lifters are dirty, maybe from debris from honing.
 
I thought it was a bad anti drain valve in the filter, changed it, still has the same problem, it takes about 3-4 seconds for the oil to reach 50psi when starting.
 
As long as all front oil galley plugs are sealing, I would replace the oil pump. Check for debris on pickup screen when you have it down.
Could be a sticking pressure relief valve in the oil pump. Good luck.
 
I replaced the rebuilt oil pump with a NOS pump and it increased the oil pressure a little, but the overall pressure was fine to begin with. It is still loosing the oil prime at startup. I did forget to mention that I recently installed a hose that connects the block to the valve cover in order to keep my vacuum pump from sucking oil at high rpm. The hose did fix that problem, but may it have contributed to this new problem?
 
The 300 in my truck does that, I'd love fix it w/o changing the oil pump. I hoped it was the oil filters, but various wix and motorcraft filters haven't fixed it. Oil pressure is good otherwise/after.
 
Yes, I also tried a wix and a royal purple filter, no change. My engine gets around 55 psi while driving, it just takes a while for it to get up to pressure at start.
 
this sounds normal to me. you are having to fill the oil filter because of its orientation. the oil drains back into the pan, and so there is no head of oil there.

if you actually lost the pump prime, then you would not get oil up to the oil filter, let alone the bearings and pressure gauge, for far more than 3-4 seconds.

you might try a remote oil filter where you can set the oil filter up in the vertical position, that way you never lose the oil in the filter. but you might still have a couple of seconds before oil hits the pressure gauge.
 
It seems strange because it never did this before, the oil pressure would normally jump to normal pressure rather than gradually build to it. I'm going to do an experiment to see if my new vacuum pump configuration is causing this. I will shut the pump off before I shut the engine off. Would vacuum in the block cause this to happen?
 
64 200 ranchero":3nzvixya said:
It seems strange because it never did this before, the oil pressure would normally jump to normal pressure rather than gradually build to it. I'm going to do an experiment to see if my new vacuum pump configuration is causing this. I will shut the pump off before I shut the engine off. Would vacuum in the block cause this to happen?

Yes vaccum could cause that problem if it was at a high enough level. Good luck :nod:
 
It seems that it is the vacuum. Since I have been shutting it off before the engine, I have not had the problem. It is functioning normally. I will have to find another way to keep the vacuum pump from sucking oil.
 
If it's controlled by an electrical switch then you could maybe install an oil pressure switch (like is used to turn off the ignistion when oil pressure is too low) to control the vacuum pump. Ie it would kept the pump from starting before the engine has oil pressure. Good luck :nod:
 
That's a good idea. Now I just have to figure out what is causing a tapping sound under load, I think it might be the lifters or perhaps my engine is pinging. I need to get it 100% before I use the nitrous again.
 
Does your engine have the adjustable rockers or the non adjustable ones? Other then trying to adjust the rockers with engine running. If you have the time you could pull the lifters out keeping them in order then take each apart for a good cleaning then reassemble, or you could replace them if your short on time. Something else you could try if you can find the Justice Brothers engine flush near your area (it should be available since it's a SoCal company) try using that it can clean up sludge, gunk, and gummed up parts with in a couple oil changes. The JB flush has worked well for me many times. Good luck :nod:
 
a few brands of oil filters have the "anti-drain back" feature which is good on our style filter placement/angle. They lay on their side so the stuff always drains back into the pan / is a lill dry on every start up. Anti drain shuts off so it stays up there w/this sorta filter.
 
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