Prime BMW oil pump or starve your bearings?

[wwillson]

A friend of mine has a less than 10 year old BMW 3 series with a straight 6 twin turbo. This week he had a mechanic replace a gasket on or near the oil pump, which caused the oil pump to drain. When the mechanic finished the job, he topped the crankcase oil level and went for a test drive. The engine seized during the test drive from oil starvation. The BMW procedure requires the pump be primed, it wasn't and the engine is now dead.

Does this scenario sound plausible?

 

[Astro14]

Yep. Some pumps need to be primed.

 

[Chris142]

The pump should have started picking up oil quickly. People used to pack them with Vaseline to get one to suck oil. Being wet it should have picked up oil immmediatly.

 

[Astro14]

Not all of them pick up immediately. Some need to be primed. Vaseline, or whatever.

How does a “mechanic” not know what’s required for the car?

More importantly, how does he keep driving with oil pressure at zero?

 

[wwillson]

How does a “mechanic” not know what’s required for the car?

I believe the mechanic is an employee, not the owner and this may have been his first BMW job.

More importantly, how does he keep driving with oil pressure at zero?

Not explainable or excusable.

 

[Chris142]

More importantly, how does he keep driving with oil pressure at zero?

x2

 

[Timmastertech]

BMW SIB 11 02 20 covers the need to prime the oil supply system after repairs.

 

[antonmnster]

I've heard of a few failures after oil filter housing gasket replacements. I haven't primed any of mine, but I've heard of too many failures to not do it in the future.

 

[928]

Mechanic screwed up- does he admit not priming pump? Shop owner owes him a proper repair & a rental car. Fill pump with something thick such as stp before assembly.

 

[The Critic]

Yes, this is not unheard of. If you perform a oil filter adapter gasket replacement and fail to prime the oil pump, this is known to happen on those engines.

 

[Craig in Canada]

A friend of mine has a less than 10 year old BMW 3 series with a straight 6 twin turbo. This week he had a mechanic replace a gasket on or near the oil pump, which caused the oil pump to drain. When the mechanic finished the job, he topped the crankcase oil level and went for a test drive. The engine seized during the test drive from oil starvation. The BMW procedure requires the pump be primed, it wasn't and the engine is now dead.

Does this scenario sound plausible?

Yes - it's a thing

The procedure is to disconnect the fuel injection and crank the car a number of times to prime the entire oil system. You're referring to the OFHG (oil filter housing gasket) job.

The theory is that the variable oil pump is to blame. At idle (and other conditions), the ECU reduces the displacement of the oil pump to reduce parasitic drag. This minimum output mode is not enough to push air locks in the lines out of the way -> spun bearing. During cranking the ECU leaves the oil pump at default, which is full flow, so oddly there is more oil flow during cranking than at idle.

There's also a theory that only versions with lines to an outboard oil/air cooler are affected, and not the models with the oil/coolant heat exchanger or no oil cooler at all, but I won't be testing that theory. (I have the oil/coolant heat exchanger option)

There are BMW bulletins and amendments to the official shop procedures on this. Experienced indys should have this information by now, there's been chatter on it for years now. Hope the mechanic is covering the cost of the engine since, really, they should have known better. Plenty of DIYers are getting caught out since you'd think that idling the engine while checking for leaks would get the job done, but it doesn't.

Personally, I don't understand why there isn't a function in ISTA for this instead of needing to pull fuses and disconnect fuel injectors and stuff. But I digress.

 

[wwillson]

Hope the mechanic is covering the cost of the engine since, really, they should have known better.

Yes, the shop found an engine with 30,000 less miles and are covering all costs.

 

[edyvw]

And they need now to vacuum fill coolant system. If they do not, they might face overheating. That is according to latest TIS.

 

[ragtoplvr]

Buick had a external oil pump for years. SOP was to pack it after repair. Sounds like a good safety item to fill sump with straight 50 racing oil before a repair. run a little. do repair and fill sump with the right stuff.

Rod

 

[Craig in Canada]

And they need now to vacuum fill coolant system. If they do not, they might face overheating. That is according to latest TIS.

The procedure for my F10 with N55, by the book, has always been to use the vacuum fill apparatus. On an advance-planned purchase I just grabbed one from ECS when it went on sale. I still haven't used it yet, but only spent ~$50 and it looks like it can be used to reduce/eliminate bleeding on any vehicle so assuming it works OK maybe it will be handy forevermore.

I'm not a fan of their removal of convenient drains. The TIS procedure is to pull the lower hose unfortunately.

EDIT: Of course YouTube is full of people who just pour stuff in burp a couple of bubbles and "have no problems". Some of the stuff on YouTube for F-series cars is scary. Lots of torque-to-yield single-use bolts not being replaced etc...etc...

 

[Trav]

This was a very stupid mistake and driving it with zero pressure an even bigger one. It may need to be packed with Vaseline, filled with oil, spun through the distributor shaft, a special tool like the X Prime for GM LS engines or pressure primed through a port in the oil galley usually where pressure sensor goes.

 

[jeepman3071]

I'm guessing it's an N55 engine. BMW has a TSB with a priming procedure which is pretty simple. Basically unplug the fuel injector harness and crank the engine a few times for multiple seconds.

 

[Craig in Canada]

This was a very stupid mistake and driving it with zero pressure an even bigger one

For clarity - as far as I know nothing indicates "zero pressure". There's no noise, no sign there's a problem, but 5 miles down the road it seizes. It isn't as egregious a mistake as ignoring a screaming oil pressure warning and driving anyways. The oil pressure sensor is happy, but part of the system is airlocked and not seeing proper oil flow/pressure.

As mentioned, I've seen some claim that it's only the OFH design where there are fittings for lines which run up above the housing and to a bumper mounted oil/air cooler that suffers from the problem, but the procedure was updated by BMW for all N55s. Even though I have a heat exchanger integral to the OFH I intend to do the prime procedure.

Design with external cooler lines:

Design with coolant heat exchanger:

 

[edyvw]

I am actually adding external oil cooler to my N52. Will have to keep in mind this.

 

[Trav]

For clarity - as far as I know nothing indicates "zero pressure". There's no noise, no sign there's a problem, but 5 miles down the road it seizes. It isn't as egregious a mistake as ignoring a screaming oil pressure warning and driving anyways. The oil pressure sensor is happy, but part of the system is airlocked and not seeing proper oil flow/pressure.

As mentioned, I've seen some claim that it's only the OFH design where there are fittings for lines which run up above the housing and to a bumper mounted oil/air cooler that suffers from the problem, but the procedure was updated by BMW for all N55s. Even though I have a heat exchanger integral to the OFH I intend to do the prime procedure.

Design with external cooler lines:

Design with coolant heat exchanger:

No oil pressure test was done after the repair especially on this and engine with known starvation issues? Some setups have a gauge like this one but it is good practice to put a gauge on the system if you have been messing with the pump, cooler, lines, etc.