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Fresh rebuild. No oil pressure. Need moral support! - Now a story of triumph!

Old 03-26-2010, 11:45 PM
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Default Fresh rebuild. No oil pressure. Need moral support! - Now a story of triumph!

OK, the rebuilt built motor is in.

I've been cranking the motor on and off for the past 4 hours. Miata battery is dead, and so is the Porsche battery now.

Spark plugs are removed.

The motor was built by a competent engine builder and I'm told the pump was stuffed with assembly lube.

I have a turbo feed line hooked up in case the gauge is bad.

I've tried pouring oil down the turbo feed line and chasing it with compressed air.

The latest attempt was pouring oil into the oil filter port through clear tubing from a funnel. I've poured half a quart in from there, while cranking at the same time. One thing to note, the oil flows through the tube faster while cranking, and seems to sit still when not cranking. This leads me to think it could be the pressure relief valve stuck open, bypassing all the pumped oil back into the pan.

A few questions...

How long can I crank the motor without oil pressure before I should start worrying about excessive wear?

Are there any methods to unstick a pressure relief valve without removing the motor?

Do you guys have any more ideas?

I know there is a port on the oil pump itself that could possibly be used to prime it, but I'm not sure which one it is.

I need to check through the oil drain fitting and see if the oil pickup tube is installed.

I've gone from excessive oil leakage, to no oil at all.
This sucks.

Last edited by Bryce; 03-27-2010 at 02:00 PM.
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Old 03-27-2010, 09:24 AM
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I would place my money on the pump not yet being primed. Those pumps are made to displace viscous fluids, not air.

I would try this if you can:

https://www.miataturbo.net/forum/t33197/



If not, take another look at how you're adding oil. You said you added through the oil filter port....but didn't say if it was the feed or return. The feed, directly from the pump, is the bottom (smaller) hole. The middle (upper, bigger) one with the threaded fitting, that would be easy to put a hose on, is the clean oil return to the block.

If you have air, I would do this:

1. Place small hose into lower oil filter port and backfill pump.

2. Pressurize crankcase.

3. Start.


I hope you have a battery charger.



On wear: I'd keep cranking to a minimum. Try one thing, crank for 10-20sec. If that doesn't get it maybe try again, but don't push all the assembly lube out of your bearings with 10 back to back 30 second cranks without changing anything.

Good luck, call if you need a shoulder to cry on.
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Old 03-27-2010, 09:44 AM
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A buddy of mine made a preluber out of the old style propane tanks which I used on my dry motor. IMO this is the ideal solution for a fresh/dry engine. Basically the main port on the top is fitted with a gate valve which will be the feed (for both adding oil to the preluber, and then feeding it to the engine). And then a hole is drilled to add a tire valve for adding air pressure. This one had it up top off center, but I wonder if near the bottom would be better so you can add the pressure when it's upside down. I filled the tank with 3qts., screwed in and shut the valve, put the compressor to it for 60psi, flipped it up side down and hooked up the feed line to the oil pump boss (pic below- I believe the B engines have the same oil feed port), then opened the valve and listened to the oil pump through the entire engine. You could hear it when I got up into the head is coming out the cam journal oil ports. Very cool.

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Old 03-27-2010, 10:02 AM
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imo it shouldnt take that damn long to prime the **** something is wrong took me about 20 secs to prime mine by hand with a drill and a modified 3/8's extension.
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Old 03-27-2010, 10:55 AM
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When I built my motor I filled the port above with oil, cranked several times with the plugs out and got no pressure.... so I said F-it, primed it again, put in the plugs and fired it up, got oil pressure within 5-10 seconds. The starter was just not spinning the engine fast enough to register pressure.

I say if you add oil to the port on the pump... fire it up. no pressure in 15 seconds shut it down then go from there.
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Old 03-27-2010, 11:44 AM
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Real men of genius = Failure of a man, in my case.

Pouring oil into the oil filter FEED port also yielded zero pressure.

Regarding the plugged port on the oil pump, is that a super special port? Meaning, is that the only hole I can pump oil into and expect it to distribute throughout the motor?
I'm going to have a tough time removing that plug if I have to.

No propane tanks are available. :(

I have a bug sprayer bottle with a built-in pump. I'm going to see how well it can pump oil. Might add a tire valve so I can pressurize it with the air compressor.
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Old 03-27-2010, 11:49 AM
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Originally Posted by Stealth97
When I built my motor I filled the port above with oil, cranked several times with the plugs out and got no pressure.... so I said F-it, primed it again, put in the plugs and fired it up, got oil pressure within 5-10 seconds. The starter was just not spinning the engine fast enough to register pressure.

I say if you add oil to the port on the pump... fire it up. no pressure in 15 seconds shut it down then go from there.
hhahahahahaahhaaaaaaaaaaaaaaaaaaaaNO.
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Old 03-27-2010, 12:31 PM
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Ok, here is what you are really trying to do.

You want to get rid of the air in the pickup tube, and in the pump before the gears.

That is the bottom most routing, with the arrows pointing forward, in the attached drawing.

I'm very surprised that the shop vac method didn't work. If you have compressor you can try pressurizing the crank case (through valve cover), which may push oil up the pickup.

Maybe pour oil into the filter feed while rotating motor backwards by hand.



Once oil has displaced all the air in that bottom pickup route between the pan and the oil pump gears you are primed and should get pressure during cranking.


EDIT: And yes you should get decent pressure during cranking if your starter is strong. I have spare, and a brand new battery, if it gets down to that.

You do not want to try starting it without immediate pressure due to the fact that the load during combustion (running) on the bearings are MUCH greater than simply spinning. It also means your cams are spinning ~3 times as fast, and they're the last part to get lubed.
Attached Thumbnails Fresh rebuild. No oil pressure. Need moral support! - Now a story of triumph!-miataoilsystem.jpg  
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Old 03-27-2010, 01:56 PM
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Well guys, I tried the shop vacuum trick again to no avail.

I gave up on trying to remove the oil boss plug, that thing is in there.

As I was walking in circles in the garage, I tripped over something... It gave me an idea.



Oil pump, meet 1/6HP commercial vacuum pump!
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In less than 5 seconds of running this pump and cranking the motor, WE HAVE OIL! Shop vacs are for pussies!
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Let the golden blood of life floweth.

Oil pressure guage still isn't showing pressure, but that is unrelated, and much less important than having oil flowing out of the motor.

Thanks guys!
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