No Oil in Front Rotor Oil Metering Line
 

While I had my engine apart, I replaced both oil injectors, both oil metering lines, both banjo bolts, and all the related crush washers with brand new OEM parts. I also swapped out my oil metering pump for a used one because my engine was running rough and I didn't have a clue. (I have since discovered what the real issue was and fixed it)

After replacing all that stuff and letting the car idle enough to prep for and then switch to evans and bleed the air out, it looked like the front oil metering line was COMPLETELY EMPTY while the rear line was full. But I couldn't really tell. So I increased the amount of premix I was using and figured I would check it later. I drove the car to O'Reily's and back and did some other stuff to my car which led to a vacuum leak and more idling to diagnose it. Once I had the engine apart again, the front line was HALF FULL of oil. So oil is flowing, but very very slowly in relation to the rear rotor - see the pic.

My question is can a bad OMP cause this or would it affect both the front and rear lines? I DID overtorque a banjo bolt on the OMP side of the line. I replaced the bolt though.

It's not unusual to have air bubbles/pockets in the lines, but you should have way more oil than that after going for a drive of more than a mile. It pretty much has to be in the OMP, unless you have PFC and someone has turned the oil injection volume down or something odd.

This is another reason why it is often advantageous to go premix only. Even if you have an OMP in place, who is to say it is working 100%? At least with premix, if you are half decent at math and responsible enough to add it every fill up, you always know how much you are getting, and if you have engine problems later you won't have to think "I wonder if that OMP had anything to do with it".

Thanks Kevin, I'll put my other OMP back in and see if it quickly fills up the line.

Is there any way to test an OMP off the car?

Alex at Gotham has tested it by running a car on the dyno with the lines disconnected. I think you should eliminate it completely, but I always suggest premix.

The problem with the e-omp's is that volume is variable with engine load by the computer, and so there is no way to check it's wide open output, or output at anything other than idle for that matter. With the old mechanical OMPs you could hold the rod open and check output that way, and you could even adjust the rod to various positions if you wanted more or less.

Thats why he ran it on the dyno under load.

Other than discussion of codes and electrical issues, I see no mention in the FSM about injection volume versus rpm/load. What was he using for a reference as to what the output should be? You have to go back to '88 to find a volume measurement recommendation, but remember that mazda has progressively leaned out the OMP injection rates over the years (including the renesis) so the old injection amount would not be applicable for an FD. How do you know how much should be coming out "on the dyno"?

No measurement, but it was literally dribbling out of one of the lines. Compare it to a good known one and you can get a general idea. The car in question was warping apex seals every few thousand miles. The scary thing is the bad pump didn't trip the check engine light.

My check engine light wasn't on either.

Probably a blockage inside the pump. The stepper motor could be operating properly so it doesn't throw a code.

Is there any chance the blockage could be in the rotor housing? I took the oil injector out and filled the hole with premix to see if it would drain into the housing. It wasn't draining on its own so I turned the main pulley. The premix level didn't drop as I turned it. Then at a certain point it pushed some of the oil back out instead of sucking it in. I guess that was an apex seal passing the hole.

Does it need need more vacuum to suck oil through that hole? (I also had the primary fuel rail pulled. So there was no chance of vacuum the way I was doing it.) Or should I spray some carb cleaner or something in it?

Edit - I almost forgot. Over the last week, the oil level in the front rotor oil metering line went down. I now cannot see any oil in the line.

The hole is really small. It needs to be forced in.

You'd need a compressed air gun to be sure the hole is open. I can't see anything getting in there to clog it, except during disassembly/reassembly time. I always blow the hole with air and be sure air comes out the other side when preparing for rebuilds.

have you watched your oil lines when your car is running? my cars oil lines are empty until i drive it around then i look at the oil while the car is still running and they are full but once i turn off the car and i wait a little bit the oil will go down about half way in the tube.

What made me think something was wrong was that the rear line was always full. It never drains out.

Any way, I do have a compressed air gun. Is it worth my time to shoot some 100psi compressed air into it? I don't want to take everything apart again if it isn't the OMP.

If I did it, I would turn the main pulley clockwise until the apex seal just passes the oil injector hole. This should position the rotors so the extra air will shoot out of the LIM or at the very least, the fuel injector hole. Then I will shoot some carb cleaner and compressed air in there.

Please feel free to tell me if I am an idiot for trying this or for even thinking there could be an obstruction in there.

I think I fixed it by pushing carb cleaner through the oil injection hole. At first when I sprayed cleaner in the hole it took a very long time to drain out. Now it drains into the housing in less than 5 seconds. I also switched from 20W50 Castrol to 10W40 Royal Purple. Also I drove it for 3 times longer than my previous test. The pics show RP in both lines.

Oh, forgot to mention that I also switched back to my original OMP. So in my opinion it was either the OMP or a blockage.

OOOps! Wow this is something I've never done. Now I feel studpid. My rebuilt 2nd gen has had air bubbles in the lines for around 17k. Good thing I've been premixing the whole time. I thought it was my nozzels (both allowed the air to travel both ways when doing the blow test). I replaced them and that still didn't fix it. My OMP may just be bad. Oh well!

Thx for posting this. Now I have yet another reason to remove my intake this weekend to see if mine is blocked as well.