[dave1973]

Hi all, could do with some advice.

I have a 320i E91 M Sport Business blah blah. It's a 2010 LCI model with 106k miles.

When I bought it, I had a couple of issues with it.

Firstly, during a run on the motorway, it was throwing up an "Oil Pressure Low" warning - if I stopped the engine & restarted it though, this warning did not come back. I checked the oil level (via the I-Drive) and it was perfect. There are no signs of any oil burning (blue smoke, wet exhaust etc.) and there don't appear to be any leaks in the engine bay or any oil on my drive.

It was also "ticking" a lot from seemingly the top of the engine and I was getting an EML (only once a day bizarrely) so I took it to a neighbours garage where he plugged it into his Autologic machine.

It came up with the following fault codes:-

29F3 - Fuel low-pressure sensor, electric
30C1 - Engine oil pressure control, static
2A99 - Crankshaft - exhaust camshaft, reference
30DA - Nitrogen-oxide sensor, signal
2AF4 - Nitrogen-oxide sensor, electric
2AF2 - Nitrogen-oxide sensor, lambda linear
2AF6 - Nitrogen-oxide sensor, lambda binary
2AF9 - Nitrogen-oxide sensor, NOX signal, coast-mode check

It also checked (using some sort of voodoo presumably) that the car needed 9 updates.

He recommended an oil flush & new oil/filter and the updates doing. He also advised a new oil filler cap as the seals can perish slightly. So, all that has been done & to be honest, the car does seem an awful lot better - much smoother and no EML coming on.

From what he's said, the codes have been cleared & the only ones that have returned are the "NOX" ones (which I can live with).

The "ticking" is much better - in fact it pretty much isn't there, however I am still getting the "Oil Pressure Low" warning, but pretty much only when I've been on the motorway. What I do have is a what I can only describe as a "rumbling" or slight knocking from the engine but not all the time. If the car is idling, it isn't there, if the car is driving, it isn't there (or I can't hear it), it's if I rev the engine then when the revs are coming down I can hear it, or when I change gear (and the revs drop).

So, any ideas as to what this could be and any recommendations for a BMW specialist in the East Lancs area?

Really need this sorted pretty quick as I'm off to France in August and definitely don't want to be returning home on a flatbed with the Mrs, our son and the MiL...

Being the internet, I've read everything from "ignore it" to "you're going to explode and it will bum your dog" and being honest, I'm now worrying slightly (not about the dog).

I've not had the car long, but I really want to sort it rather than get rid as other than this, I love the car. It's my 3rd 3-series (E36 Touring and E46 Cab previous) and they really do get under your skin!!

Cheers for reading, Dave

TL: DR - car making a funny noise and getting "low oil pressure".

[Russbmw]

First of all, your NOx sensor is dead, and that may (or may not) be affecting the engine running in general.

The ticking sound probably isn't anything to worry about, as the injectors are quite noisy - but obviously without hearing it,, it's impossible to say.

Rumbling sound is a bit weird and worrying, made weirder and more worrying by the engine systems telling you there is an issue with oil flow around the engine - but I don't know what that might be I'm afraid, but oil starvation can break engines.

Not what you want to hear, but my wife had a 320i and that engine was nothing but grief - throwing random EML's, sometimes whilst running absolutely fine. Sometimes it would be down on power, then get itself into a never ending cycle of stalling and automatically restarting. Other times would run like it was firing on 2 cylinders and the engine would shake like it was trying to tear itself from the mounts and the EML light on again. Turn it off and on again, and it would run absolutely fine, no EML but worryingly absolutely no codes stored for this automotive equivalent of an epileptic fit - so I couldn't actually see anything on my diagnostic kit, and neither could my local BMW dealer.

All the above would happen completely at random, no bearing on ambient temperature or weather conditions, speed, or how long the car had been running for. Sometimes it would be fine for months and months on end, other times it would shit itself several times over in the space of a week.

After having the coil packs replaced under warranty and me fitting a new NOX sensor, it all seemed ok for over a year, then started playing up again - by which point BMW had no clue and my missus had no trust in the car, so it got sold.

In short, find yourself a BMW specialist....a good one, as otherwise you'll be changing bits willy nilly.

BUT

First off, how long have you had the car, where did you buy it from and has it got any kind of warranty? Was it also showing this faulty when you bought the car (your post implies it was)?

[Aragorn30d]

Oil pressure warnings are fairly serious.

If it was a true warning, its very likely that you've caused damage to the engines bearings by continuing to drive it with no oil pressure. The ticking also correlates with no oil pressure, the hydraulic tappets require oil pressure to stay "inflated" and if the pressure is low, they lose tension causing the ticking noise.

The bearings require oil pressure to work, the crankshaft floats on a cushion of oil, created by the oil pressure feeding into the bearing journals. With no pressure, the bearings end up running metal to metal, overheat and the ruin your day.

I had a similar incident recently with my track car. Its had a few electrical gremlins and the LCD panel on the dash cluster didnt work. Driving on track i got the warning chime, but couldnt see what it was warning me of. Theres only a small number of things that can bring that particular warning chime on in that car; brake fluid, ABS, Coolant temperature and oil pressure. Everything checked out ok, engine sounded healthy, brakes and coolant were fine, so i marked it down as an electrical gremlin and set off again. Few laps later it came on again, i ignored it, and a lap later the engine stalled. Amazingly after it cooled down it started and ran, sounded totally normal, but once the oil reached 90c the pressure dropped off a cliff. Stripped it down and found a spun bearing shell, and some sludgey deposits in the oil pump pickup, that were presumably blocking the intake of oil.

Given the knocking noise your describing, its probably spun a shell. The knocking is the conrod clattering around on the worn bearing journal. Knocking on overrun is usually the classic first sign of a big end failure.

If you fix it now, you might get away with a crank grind, a new rod and a set of bearings. If you ignore it, that rod will probably exit stage left thru the side of the engine block. Might be cheaper to simply replace the engine either way though, especially if you cant find the root cause of the oil pressure issue.

[dave1973]

Originally Posted by Russbmw

BUT

First off, how long have you had the car, where did you buy it from and has it got any kind of warranty? Was it also showing this faulty when you bought the car (your post implies it was)?

Cheers for replying - much appreciated.

I've had the car for about a month - bought it from a trader (home based but a proper Ltd Co rather than a bloke selling cars by the side of the road). The "ticking" thing seems fairly common & to be honest has pretty much gone after the oil/filter flush and change, but I think since this noise has gone, the "rumble" is more noticeable.

The "low oil pressure" warning came up a couple of days after getting the car & the lad I bought it from agreed to pay for an Autologic scan which then led to the oil change being done. He sent me £150 to get this done.

After having the oil change & updates done, the faults were cleared & then rescanned & they had all disappeared (bar the NOX). The pressure warning has happened again though, although the car doesn't seem to be leaking/using any oil.

Speak to the trader as a next step?

FWIW, I paid just over £7k (£3.5k cash + £3.6k trade in) and got the car with a fresh MOT, new rear pads and a pair of new front tyres. Other than the rumble, it's a fantastic car - space grey with saddle brown leather and it can fit 6' x 3' plasterboards in it

I'd rather get it sorted than reject it if I'm honest, but maybe that's because I'm a bloke & quite pig-headed.

[Russbmw]

No matter how much you like the car, it not be much good to you with a seized engine, or when you're staring down the barrel of an engine rebuild bill.

The guy sounds fairly reasonable. If I were you, I'd speak to him again explaining the oil pressure and rumbling noise issue, and ask if he wants to have it investigated, or if he's happy for to take it to an independent Bmw specialists to be looked at and sort out reimbursement later. Get anything you agree in writing, just incase (I've tended to correspond by email in the past).

Until you know what the problem is, neither you nor he will know what they want to do with the car. It could be nothing major, or it could be an expensive one.

As a consumer, you're kind of covered by law, seeing as you've only had the car a short time, although from experience, it's not plain sailing and can be a right ballache if the dealer is non cooperative, so try keep him on side.

[Aragorn30d]

Oil pressure is nothing to do with leaks or using oil. It means the oil pump is unable to produce the pressure the engines rotating parts require for proper lubrication.

Given its still doing it after the oil change and flush, its very likely indicative of a real mechanical issue with the engine.

Would i be right in guessing the times its thrown the light on have been longer journeys, and that the car usually does short trips?

[dave1973]

Originally Posted by Aragorn30d

Would i be right in guessing the times its thrown the light on have been longer journeys, and that the car usually does short trips?

Exactly that. If I do my normal day to day driving (journeys of a few miles at normal town speeds) I don't get any warning. It's when I go on the motorway (running at 60+) do I get a warning.

Bizarrely enough (and probably completely coincidentally), I've had the warning twice on a motorway at exactly the same spot - immediately after a big climb.

[Aragorn30d]

Yep, much the same as my track car.

When the oil is cold its thicker, and the pump can manage to maintain pressure despite the failing bearing. Mine had perfect oil pressure from a cold start.

When the oil heats up it thins down, and most cars can take a good 5 or 10 miles of driving before the oil reaches operating temperature. And ofcourse a big climb puts more heat into the oil and it gets thinner still.

All completely normal, until your engines half broken and the pump cant manage to maintain pressure with the thin oil.

You really need to get the sump off and the bearings inspected. Mine was immediately obvious on removing the sump that the big end bearing on cylinder 1 was shot, you could see the heat damage on the conrod.

[dave1973]

Originally Posted by Russbmw

No matter how much you like the car, it not be much good to you with a seized engine, or when you're staring down the barrel of an engine rebuild bill.

The guy sounds fairly reasonable. If I were you, I'd speak to him again explaining the oil pressure and rumbling noise issue, and ask if he wants to have it investigated, or if he's happy for to take it to an independent Bmw specialists to be looked at and sort out reimbursement later. Get anything you agree in writing, just incase (I've tended to correspond by email in the past).

Until you know what the problem is, neither you nor he will know what they want to do with the car. It could be nothing major, or it could be an expensive one.

As a consumer, you're kind of covered by law, seeing as you've only had the car a short time, although from experience, it's not plain sailing and can be a right ballache if the dealer is non cooperative, so try keep him on side.

To bring a (sort of) close to this thread...

I took the car to 2 engine specialists & they both said the same thing - the engine needs rebuilding as it's likely to need either a new crank, oil pump, pistons or all 3. No matter which way you look at it, it's knackered. This is where it gets interesting - the trader has decided it's no longer his problem & it's nothing to do with him.

The abridged version of this tale is I've now got rid of the car (sold into trade as I wasn't going to sell it private), bought a replacement car (not a BMW - very disappointed with them if I'm honest) and I'm taking the dealer to court for my losses (basically the difference between what I paid for the car and what I could sell it for with a knackered engine less than 2 months later). The car was supposed to have 12-months warranty, but this never materialised & he's claiming it never had one (despite the advert saying it came with one).

Engine rebuild was anywhere from £1500 to £3000 depending on what was needed once it was apart & I simply wasn't prepared to pay that on a car I'd had less than a couple of months.

It's a shame as I liked the car, but there you go.