Oil primelessness, no oil pressure at start!?
 

(1997 stock na beater...https://www.miataturbo.net/forum/t27268/)

We replaced the bottom end on this car and it ran great for a week or two, but now there is no oil pressure until the car has idled about 10 seconds from cold. (Why don't we turn it off!? Because we just want to beat on it and use it until we do a real build on the old block..) The oil pressure goes normal after that initial start up time. We replaced the oil filter and it seemed to shorten the time but probably just in our minds.

Any suggestions?

If it is the oil pump, can it be replaced without removing the engine? This thing gets much better gas mileage the the dually diesel.

Lost this all after typing it...

Try dumping the oil and putting in some walmart special synthetic with a WIX oil filter from NAPA. See if the situation improves. Either that engines is missing all the rod bearing and half the cam caps, or the relief valve in the pump is sticking. Or a severly clogged pickup tube. Did you fill the engine oil with accorns, headgasket repair, or silicone by chance? :eek5:

Maybe the cheap oil filter doesn't have an anti drainback valve.

It could be that the gauge and/or sensor is going bad after the years, or it could be the oil pump (weren't '97s known for having high rates of oil pump failures?), or the filter, as mentioned. First I'd test with a real (not electric) gauge, then I'd gamble on another filter (since they are cheap) and then maybe suspect the oil pump.

You can hear the difference. :(

Can the oil pump be changed with the engine in the car?

you could get out a hoist and drop the subframe, but that might not be worth the drama.

Did you maybe not get the oil pick up tube gasket right? Or, did you check the oil pump at all? I seem to remember mine being a pain, but only on first start. "primed" the pump and everything has been ok since

Its so inconsistent, something has to be messed up. Just have to pull it, again. He's got a backlog of cars to turbo, so it will have to get buried in snow for now. :(

No more donuts. Damn FWD.

Almost gotta be a sticking relief valve. Dump the oil and fill it with automatic transmission fluid. Idle for 5 minutes with it cold. Dump. New oil. Probably fixed.

usually it is oil filter that has a leaking rubber membrane, and oil pump has to pump the whole filter with oil.
I changed two filters until I bought MANN. Now it works great ;)

ATF = the Jam for cleaning.