After losing my rebuilt motor to a boundary oil pump, iv rebuilt it with a stock pump housing and im currently breaking the motor in.
Im trying to be as cautious as possible so iv upgraded to a AEM oil pressure gauge, and just want to verify my pressures are good so i don't lose this motor as well.
The first few days the pressure would be around 18-23psi at hot idle, sometimes dipping down to 16 but raising up after a second or two of idling. during a cruise i was seeing rpm+10. so at 2700rpm i would see around 37-40psi.
last night while driving i came to idle and the pressure was low at 11psi. Overtime it got better but was still lower at 16-18psi. Driving around at the same rpms as before i would now only see 27-30psi at 2700rpm.

I didnt notice any odd noises and the oil im running only has about 150 miles on it and is AEM 30w break in oil. Not low on it either.

I know im probably over reacting, but i just want to check with the experts to make sure im not about to kill another motor.

For further refrences, its a VVT 2003 NB with the kraken turbo kit.

 

What ever happened with your other engine? You never updated the thread after some suggestions from other members.

Those pressures seem safe, if a little low. What kind of bearing clearances did this motor have going together?

 

The other engine absolutely thrashed the bearings and crankshaft unfortunately. I had to have the crank taken to a machine shop and completely rebuild the motor. luckily my head was safe, but from what we can tell it seems the BE pump stuck its relief valve and managed to score the housing and gears to hell and back, we are thinking the housing they use doesn't have the best clearances. Boundary wasn't much help and seemed more focused on selling me another pump than actually helping so i just went with the pump that worked from the start with upgraded gears. Is what it is....shrug

I believe we are running 0.0022-0.0025 on the rods and 0.0018 on the mains.

 

Oh man, that blows!

Those clearances are definitely on the tighter side. Accordingly, I'd expect to see a good bit more pressure than what you've mentioned. Just to confirm, are you running the higher volume VVT pump?

 

I believe so, its the stock Mazda pump housing that came with the car with upgraded gears. We made sure to clean it and make sure there was no burrs or any issues with either before putting it in the car. Previously before the initial rebuild it ran on that pump set up no problem for about two years. Granted i have no idea what the oil pressure was before the rebuild due to only having the stock dummy gauge.

I just find it odd that the pressure dropped all of the sudden but is still within acceptable specs. I feel that if the valve had stuck again it wouldn't build pressure quickly once i got on the throttle, since before when it stuck on the boundary pump i struggled to build past 15psi

 

What weight oil and what is the max oil pressure or pressure above 5k rpm?

I recommend changing the oil after the first warm up and then after the first hr, especially on a rebuild that had a catastrophic failure. The head has oil passages as well as the block. Everything needs to be cleaned thoroughly.

 

Right now its running 30w break in oil from amsoil, unfortunately i don't remember the pressure at 5k rpm since i havent brought it up near that since we broke the rings in.
We cleaned the head as best as possible, the block was completely rebuilt and cleaned by the machine shop and then by us as well. Did a change right after the initial break in. We are planning to do another change over the weekend since the car has about 200miles on it now.

Iv tried my hardest to prevent this one from going KABOOM haha

 

5,10-30 or straight 30? 10psi at an oil temp of 200+ at 900-1krpm is ok. After track use or a high speed spirited run you might see a lower pressure from an increased oil temp. The max pressure should be 55-70. There is no need to go over 70. If the pressure is a bit low you can run a slightly higher viscosity. I prefer a 5,10-40wt oil for these engines. I have run 15-50 M1 with good results as well.

 

just for a point of reference, my 250k mile slightly scored pump I just put back in my rods only motor, has been making around 25 lowest 22 at hot idle on my digital gauge. ill get about 50psi cruising around 2.5-3k, its not exactly scientific, but again, just for reference. its a stock vvt pump. I havent gotten the oil HOT, but warmed up ive seen the lowest as 22 breaking it in so far. 10w30 vr1

 

Sounds like another sticking oil relief valve to me. A fresh, brand new rebuilt motor with a VVT oil pump should do better than that. What does it show at 3 or 4 thousand RPMs? From memory, I think my vvt motor is around 60 psi at 3K with 200*F oil.

 

Are you certain you reinstalled the oil squirters? Definitely trust the gauge? That weight oil with those bearing clearances should be much more in line with what Pat quotes, I’d expect 70-80 on cold start, around 20 hot idle, and ~40-65psi anywhere above like 1800rpm.

 

Break in oil is straight 30.

 

They offer break in oil in multi weight options now. Don’t answer for OP if you don’t know.

 

Amsoil sells exactly one break in oil. It's SAE 30.
But ok m8, sorry for trying to clear that up.

 

Oh I missed that he said it was Amsoil

 

Like others have said you should ideally have more pressure than that. I'm running 5w40 rotella for the winter and I run m1 15w50 in the summer and I generally see 20psi warm idle and 50-65psi @3500rpm when warm. I run a boundary pump I can't remember which model it was at this point.