Well, the MINI is the gift that keeps on giving! 137K miles

The oil low pressure warning light came on last night while on the interstate at 70 MPH. I immediately pulled over, shut the engine off, and towed the car home.

This morning, checked the engine oil; the level was fine; no external leakage, and the oil is new (about 2K miles on it); always use MANN filters.

I pulled the low pressure switch, and it checks good. Now I need to know what the pressure is at the low pressure switch port on the cylinder head. This kit has the M16x1.5mm adapter, so I'll order that next.

https://atdtools.com/5608

I've read that there is a way to check the oil pressure at the bottom end too so you can isolate the cause of the low pressure to the oil filter housing assembly. Anybody know where to tap into the oil pressure in the block?

Thanks!

 

After a little research, and a discussion with Mike from ECS Tuning (Thanks Mike!), I drained the oil (had 3K miles on it after I checked my records), and pulled the oil filter. Does the position of this bypass check valve look normal for the N12 engine oil filter housing?



After installing a new filter, I pulled the exhaust VANOS solenoid to look for contamiantion, and one of the o-rings was missing. I thought it must have rolled off the valve when I removed it, but it wasn't in the bore in the cylinder head.



No o-ring here ....



I know the engine wouldn't run properly for last 12K miles (when I installed it) if the o-ring was missing, so what the heck?

 

There isn't an O-ring there on the VANOS actuator solenoid. So no need to go looking everywhere for it. That recess at the tip end seems like it needs an O-ring, it actually doesn't.

 

Thanks for the help! I mis-read the real OEM BOM. There are two o-rings listed because there are two VANOS solenoids listed (intake & exhaust for the N12).

 

Sadness ... no oil pressure at the oil pressure switch with my pressure gauge.

So, what's next? Before I pull the oil pan to inspect the oil pump drive chain and gears, I was thinking I could pull the non-return valve and connect my new direct-reading gauge. MINI Mania guys say "The Non-Return Valve is connected in series with the solenoid valve for VANOS actuation and its purpose is to prevent the VANOS and its oil channels from running dry."




If the non-return valve failed, it could (in theory) block oil to the cylinder head and cause my result. But, wouldn't that cause a DTC for VANOS operation? Come to think of it, if the oil pump failed, wouldn't that cause VANOS faults to set in the DME? I only got the low-oil pressure warning light, no codes.

 

Here's the backstory:

https://www.northamericanmotoring.co...ing-light.html

After preliminary checks, an oil & filter change, and a new oil filter housing cap, I pulled the non-return valve, and cranked (not started) the engine. I didn't get any oil flow from that port, so I pulled the oil pan. Was pleasantly surprised I could do that without having to drop the exhaust and exhaust manifold!

Wedged between the plastic pump cover and the pump was the head of the sprocket attachment bolt.



So I pulled the pump and extracted the other half of the bolt. The pump spins freely.



Here are the bolt (pieces)



A 8x picture of the bolt looks like a manufacturing defect with the bolt, but I've sent pictures out for analysis. Notice the void in the metal; this reduced the strength of the bolt. I'm surprised it took this long to fail.



Crazy how a defect of a $5.00 part could cause catastrophic engine damage. Off to the store for a new bolt.

 

Definitely a unique case. But glad you figured it out.

 

Oh it gets better. I reinstalled the pump and attempted to tighten the bolt, I couldn't pull tension. Looking closely at the parent threads in the pump, the shaft is split. I'll post a picture later.

Time to order a new pump.

 

Turns out the broken bolt was just a symptom of a bigger problem. I pulled the pump and tore it down. Lookie what I found inside.

 

That explains the broken bolt and stripped out threads now doesn't it? The vane got jammed in the output gear. Wonder what made the vane snap though, that's not an ordinary failure in my experience, regardless of the engine manufacturer.

 

Found the EXACT same problem today after reworking heads, changing cams and timing chain. That's a pretty thin casting for the impeller.

 

I wonder too; that's why the pump is going to Master Industrial tomorrow for a full failure analysis; I'll post the report when I get it.

 

No impeller; those are pump gears.

https://en.wikipedia.org/wiki/Gear_p..._animation.gif

 

Here are mine...

 

Damn! Same problem. I'll shoot Mike over at ECS Tuning an email. Perhaps he can discuss these failures with his pump vendor.

I've owned a lot of cars and driven a lot of miles over the years, but this was my first oil pump failure.

 

JC, how many miles are on that engine?

 

96k. I got all of my parts off of an engine local to me in a salvage yard, with 53k

 

It's alive!!!

The new pump finally arrived, and while I was at it, I also changed the pump sprocket, sprocket bolt, and pump sprocket cover. I also replaced the oil filter housing gaskets and pulled the poorly fitting Magnaflow exhaust manifold so I could install the original exhaust manifold. The flange on the Magnaflow part wasn't flat and I had an exhaust leak from day 1. My scan gauge is showing F/A ratio of 14.7 at idle now instead of 13.7, so my gas mileage should go up.

To my surprise, oil pressure with the new pump was 48 PSI at idle; I was expecting 10 PSI because that is the spec in both the Bentley service manual an newtis.info. Oil (Castrol 5W30 Syntec) is new as is the (Mann) filter. I will be looking for a oil pressure gauge to install soon.

Looks like pulling over and immediately shutting the engine off saved me from a full rebuild!

 

That's great news!

 

Congrats. Great detective work.

 

After telling my brother the MINI story this week, he sent me this.