Rebuilt Miata Engine, No Oil Pressure

So, dropped the 2000 Miata engine I rebuilt a few months back into my 1990 Miata and finally got around to starting it today. But it has no oil pressure. Not cranking, not running. And none in the filter, so I know it's not a sender or gauge issue. It has a brand new standard pump from Flyin' Miata, as well as a new pickup tube gasket.

Now, doing some reading, I discovered that the manual recommends packing it with petroleum jelly, but because they had that under the Inspection section, I didn't see that (I was putting on a new pump, not checking out an old pump). Honestly, the thought never crossed my mind, at work we put oil pumps on 5.3L trucks all the time and never prelube them, just hit the key and they have oil pressure instantly.

Some guys say this is absolutely necessary, and that that it will never self-prime.  Others say crank 30-40 seconds with the plugs out and it should prime, which I've tried several times to no success (I did coat everything in a heavy coating of assembly lube). I've also tried pouring oil down the center port of the filter mount.

Am I missing something? Am I going to have to yank the engine out and remove the pan? Could I apply a suction at the center port of the filter mount to pull oil up to the filter?

You could pressure lube the system through the gauge port....

When I redid my rover motor I couldn’t get pressure even after priming the pump (which was pretty easy other than dropping th pan). It turned out I had a slightly different timing cover that was blocking one oil port. 

I’m not sure the specs of what your working on, but can you drive the oil pump with a drill? Some motors allow you to do that through the dizzy. 

grover said:

I’m not sure the specs of what your working on, but can you drive the oil pump with a drill? Some motors allow you to do that through the dizzy. 

Not an option. Oil pump is driven of the front of the crankshaft, while "distributor" is driven off the back of the exhaust camshaft.

+1 on pressurizing the system through the gauge port.

Don49 said:

+1 on pressurizing the system through the gauge port.

As in feeding compressed air in the port?

NickD said:

Don49 said:

+1 on pressurizing the system through the gauge port.

As in feeding compressed air in the port?

Pressurized vessel holding oil and apply psi to first oil in

Very curious about this. I put a new pump in a 1999 and it didn't even occur to me to prime anything. Glad that worked out. 

mazdeuce - Seth said:

Very curious about this. I put a new pump in a 1999 and it didn't even occur to me to prime anything. Glad that worked out. 

That's what has me worried is that some people say to just crank and it should build pressure.Makes me wonder if I have something else going on,

Right now removing the plug that threads into the pump and goes into the pump cavity and filling that full of oil.

Update: removed the plug and filled the pump with oil, then cranked. Still no pressure at the gauge and no oil at the filter. I'm really starting to think something is wrong internally.

Is there a dent in your oil pan? I've seen pumps with snapped pick up cause the oil pan was dented.

Did you fill the oil filter before screwing it on?  without a primed pump, it may not allow the air to pass.  you can try applying a vacuum to the gauge port while cranking putt the oil up.

Did you fill the oil filter before screwing it on?  without a primed pump, it may not allow the air to pass.  you can try applying a vacuum to the gauge port while cranking putt the oil up.

44Dwarf said:

Is there a dent in your oil pan? I've seen pumps with snapped pick up cause the oil pan was dented.

Nope, it's a cast-aluminum pan. And I had the pan off when I overhauled this thing. Engine was torn down to the bare block, new bearings, new pistons, new rings, new oil pump,, all new gaskets around. Filter is first in line after the oil pump, and I have nothing there. At this point, I can't believe it's just that pump hasn't primed. So it's either a pump, a leaky pickup tube, or maybe a pickup tube that's up against the pan.

I'm pretty berkeleying devastated currently.

The hitch being that pulling the pan is far from trivial. Either the motor comes back out or the crossmember has to come off. If the crank is spinning that means the oil pump has to be spinning. If the pickup is still on and it's full of oil then.......not many other options.

In reply to mazdeuce - Seth :

Honestly, with all the supercharger plumbing and stuff topside, I think dropping the subframe may be easier

A friend had the same problem with his fresh rebuilt BP. He ended up taking the filter off and squirting oil into the feed port for the filter as sort of a backwards ass way to prime the oil pump. It worked for him so it’s probably worth a shot before you yank the cross member. 

In reply to Spoolpigeon :

I actually tried filling the oil pump through the pipe plug in top of it. Not sure how I would fill the outer ring (which is what feeds the filter from the pump), short of drilling a hole in a filter and forcing oil in that way

Have you started it or just cranking? My last miata engine wouldn't build pressure while cranking but it came right up when i started it.

EvanB said:

Have you started it or just cranking? My last miata engine wouldn't build pressure while cranking but it came right up when i started it.

I started it first, and it didn't run very well (needs tuning) but it wasn't building any pressure then. So then we dove into trying to get pressure from cranking. But like, I've said, filter is first in line after the pump and there's nothing there at all.

Have you ever considered adding an accusump?  This might be a good excuse to buy one.  At least that way you know you are lubricating your engine while starting it and getting it to build pressure.

Nerve wracking, ust waiting for the oil pressure needle to show signs of life on a new build. 

Dumb question -- did you just add this pan?  Is it higher capacity than stock?  i.e.  Does it have enough oil in it?

Silly question perhaps, but have you verified that your oil pressure gauge is functioning properly?

Ranger50 said:

NickD said:

Don49 said:

+1 on pressurizing the system through the gauge port.

As in feeding compressed air in the port?

Pressurized vessel holding oil and apply psi to first oil in

Have you tried this yet?

This process helped me diagnose a no pressure issue with a 914 rebuild.

Really silly question...

Does the engine have oil in it?

I had a friend rebuild a small block Chevy once and the lifters wouldn't Prime. He filled the motor full of oil, like pulled the valve covers and dumped oil until no more would go in. Turn the crank a few times and drained it back dipstick full. Said it worked for him?