E46 318i Touring: Oil leak fixed! Rubber rocker-cover gasket was the culprit!

It's about time I got back to wrenching on some Beemers after a busy hiatus, so where better to start than with the massive oil-leak on my E46 318i Touring. The car hasn't seen much use over the winter months, but as I start to need it again for its cavernous load-lugging functions, I figured it was time to spend a bit more time getting it right.

I was going through about a cupful of oil every 100 miles or so (I think that is a pretty favourable estimate to be honest, more like half a litre!) and worse than the cost of all the topping-up, smoke continued to billow from not only the sides of the bonnet (hood) while stopped at traffic-lights, but also straight into the cabin with the blowers turned on. This meant for the last 12 months I have had the climate-control set to full recirculation mode and on low, making de-misting the windscreen a nightmare on colder days.

I could see the oil-leak was coming from the rear left side of the engine, as it so often the case with N42 engines and assumed it to be the vacuum-pump (like with my E46 318ci in this this post), but after removing the rocker-cover (cam-cover) I found it was actually the rubber gasket itself. The thick rubber gaskets tend to harden and go brittle over time and almost completely down the left side of the cam-cover there was noticeable leakage, primarily at the back corner, next to the vac-pump of course. The gap at the rear-left corner was so pronounced I feel you could have slipped a credit-card through with a little force and touched the back of the cam-shaft! This was allowing a constant drip of oil out onto the heat-shield and down onto the exhaust-manifold, as shown by the arrows in the picture and causing most, if not all of the smoke.

Luckily, I suppose, I have been working through the Covid epidemic, so I am classed as a 'key worker' and had a day off, so I managed to blag Euro Car Parts that it was essential work and instantly collect the new Elring gasket (£22, but eBay alternatives are as cheap as £9.50 if you can wait!) and some Corteco White instant gasket-sealant (£7), though they still had me waiting for an hour outside!

Knowing how prone the top-end seals of the N42 are to leaks and not wanting to take any chances of removing the rocker-cover again anytime soon, I slapped on a liberal bead of the Corteco sealant over the vacuum-pump ring and along the entire left-side (lower) surface of the cylinder-head top edge along with the new rubber-gasket. The job does not take long at all (I will post a guide soon), with removal and refitting of the cam-cover only taking around 30 minutes each and that's taking your time...

Needless to say, this has stopped the major part of my oil-leak in this area! Not only has the oily steam stopped from the sides of the bonnet while stationary, the smell/smoke from the climate vents has now ceased and the car is no longer consuming oil at a silly rate, so I would say job done! There is still a tiny weep of fresh oil coming from around this area, but nowhere near like before and, after a run where the engine is warm, there is no dripping pool on the under-tray! For the money I spent, the difference in convenience is worth vastly more! I would have spent the ~£30 I did in oil in a couple of weeks using the car daily, so if you have this problem, it's safe to say this is the culprit and get it sorted!

E46 318i: Front-of-cat o2 / Lambda sensor replacement [Fault Code 271D, 271A, 271B] [Rear-of-cat 271C, 271F]

E46 failed its MOT on the O/S rear tyre and O2 emissions too high. I duly replaced both rear tyres with a new pair sourced through work for just £23 each and they are V-rated so should be ok for the Touring. As for the O2 level being too high, I was told this was a fault with an O2 / Lambda sensor so I plugged in a Snap On Modis scanner to see if this was right.

The code I got back was 271D, as in pic above, which is the up-stream or 'front-of-cat' sensor heating. Codes 271A and 271B show fault at the same sensor, but are labelled directly 'front-ofcat-sensor' with no heating suffix. This sensor is located slightly forward of the catalytic-convert mounted about halfway down the car's underside, as in the diagram below. The one shown to the rear of the cat is the down-stream or 'rear-of-cat' sensor. Code 271C applies to this rear sensor, along with 271E for Rear O2 sensor-heating. The two sensors, though essentially the same, are different parts and part numbers due to the rear sensor having a longer wire. [List of emission based fault-codes here.]

I got hold of a used sensor taken from another E46 318i from www.marobmwspares.co.uk for £18. I prefer used OWM BMW parts that come with a warranty / guarantee over cheap spurious items. The least expensive spurious items start at about £20 for a sensor that can be used for either front or rear of cat, having a long wire than can be cut to length with two bare wire or universal wire-terminal ends that require the original plug to be soldered on from the broken sensor. On the other end of the spurious price range was Euro Car Parts, who offer an OEM-quality sensor for £68, which is pricey but comes with the correct wire-length and plug fitted.

My old sensor proved very tricky to remove with the car on fixed-ramps and I would not like to attempt it with jack and axle-stands. I was unable to crack the sensor off and unscrew it even with the use of special Lambda-sensor sockets and it began to round so I ended up booking ramp-time in the workshop of the company where I work and lifted the E46 Touring on a 2-post ramp to give loads of access underneath. To avoid the risk of breaking the Lambda-sockets or further rounding the sensor itself, I decided to cut about half of the sensor off using a 3.5" cutting-disc and used a 22mm deep impact-socket with a long breaker-bar to finally crack the sensor off. It was pretty seized on, but once cracked just unscrewed by hand. The replacement sensor screwed straight in and swapping / mounting the plug was easy to make for a 5-10-minute job once the car was positioned on the ramp legs.

RESULTS:

The emission test result went from 2.2, with a maximum of 2.0 allowed, down to just 1.0 with the faulty sensor replaced. There is also a significant drop in neat-petrol smell emitting from the rear of the car when it is started from cold, so I'm glad this problem showed itself and got fixed.

Article on /BMWTech subreddit: https://www.reddit.com/r/BmwTech/comments/d5v30t/271d_lambda_sensor_front_of_cat_which_one_there/

E46 318i - Broken Coolant Hose! [11537572158]

 After about 650 miles in the E46 Touring the radiator light came on. Just the amber warning, to let me know it was getting low, not the red warning when it is running out and I refilled about 1.25 litres of water / coolant to the engine. This seemed about right to me, as I feared it may be using a bit of water and there was plenty in when I bought the car so 1.25L in 650 miles isn't catastrophic and can be lived with.
About two weeks later the radiator light came on again and I dutifully refilled 1.25 litres, but the car had only covered 120 miles so I knew something was now amiss, only for the light to come on yet again after just five miles of my six mile round trip to work. Under the hood with the engine running I could see a huge pool of water in the under-tray and a drip, which after much tracing turned out to be coming from a slim rubber hose that connects to the left side of the cylinder-head [N42 engine]. It was a constant drip, but when I wiggled the hose-end the coolant began to spray round the engine-bay, so here was the culprit. Turns out the hose-connector into the head was completely sheared off, as you can see in the pic, and should extend about half an inch into the housing. The only thing holding any water into the upper engine at all was a single M6 thread screw.

The hose in question was BMW Part No. 11537572158, shown in the diagram connecting the thermostat to the cylinder-head. This is a common fault I am told on N42 and N43 engines, along with several other coolant hoses that have plastic end connectors, particularly in the US where kits can be purchased to convert the brittle plastic ends to aluminium ones. This seemed unnecessary for me, given the cost of a replacement part and the age of the car.

As there are so many coolant hose variants, finding the right used OEM one on eBay and the like can be difficult, but they do pop up. I was able to get a new spurious part through work for just £18, but I'm sure commercial motor factors will not be much more expensive as long as they have stock. Spurious hoses tend to come with a new rubber O-ring fitted. BMW dealerships will charge a premium, but at least fitment is guaranteed and they are revised parts, though these may not come with the rubber O-ring which will also need to be ordered.

E46: New secondary air-pump - one last bash...

Thought I would have one ultimate stab at the E46 as it is such a nice car to drive and only let down by shabby bodywork, which I can do something about, and the super low idling problem, which apparently I can't.

I refitted the Vanos-actuator and checked for anything I'd disturbed under the inlet manifold, finding a loose wire connector which I clicked back in, though the CCV was all plumbed up fine. A replacement secondary air-pump and its hose / filter was £30 and the only thing now missing from the inlet arrangement. It took no time to fit, just two 13mm bolts holding it on and swapping the hoses over, but has still, alas, made no difference.

I've spent nearly £300 on parts to cure this engine of its fault, but nothing has done the trick so I guess I will have to call it a day and scrap her after all. Again a shame, as it has 9 months MOT and 4 months tax left on it. The running gear is sound, I sorted the brakes and the engine runs fine when underway, pulling well in all gears over 1500rpm. Handling is as sweet as any E46. The interior and exterior are in terrible nick, but thats nothing that couldn't be sorted with a day or two spent on it. That's only worth doing if the car is useable however, and it sadly isn't.

On top of the impossible low-idling, the handbrake-shoes have collapsed in some way and stick on completely in reverse with the handbrake off. This is probably from being used so much to stop the car while my right foot was still keeping the revs up, but is extra work regardless. A large M12 bolt holding one of the front shock-absorber struts broke while I was attempting to fit the coilovers months ago. I've been driving on it and the strut hasn't moved at all, but it too will need replacing at some point and removing the stud will be interesting. Inside the car, the fan for the heater/blower doesn't work and the driver's door card is missing, meaning no speaker or door handle. Exiting the car with dignity can only be done by lowering the window and reaching out for the other handle, but all these foibles I rather liked. Using it every day was a nightmare though and, with the 5-Series engine swap underway I just won't have the time and money to restore it, so I'm hoping I can get the £200 I paid for it back from a breaker. That means I'm down about £300 on the whole deal. I could make the £500 back and probably more by breaking the car, but I could really do with it out of the way quickly now so a loss it may have to be.

E46: CCV + Intake Re-con.

Following on from this post - E46: Inlet full of oil! Re-con time. - where I discovered the intake-manifold was full of oil, I decided to give the entire thing a good clean out. The sensors, actuator and throttle-body were removed and given a good rinse with brake-cleaner. There was still oil pooling in the manifold, so I just kept on squirting brake-cleaner down the ports and turning the manifold round to run it all back to the main plenum. The Vanos [or Valvetec, whatever] seemed to benefit the most from this as the tubes were full of oil and sticking a bit. They now slide up and down freely and hopefully the electronic-actuator will still work now its clean.

The CCV sits below the inlet-manifold in a plastic-housing, along with the main wiring-loom box. Separately it looks like the diagram. These are known as 'vortex' type breathers, as crankcase pressure is relieved from the head via tube [3] and oil is separated in a spiral and runs down tube [4] back to the sump. The air-pressure is then vented via a diaphragm through tube [2] into the throttle-body, which provides a constant vacuum that keeps the engine as a suitable idle. When the vortex is clogged with oil and rust, pressure builds up in tube [3] and backs up into the head, down into the crankcase and forces oil and air back up tube [4]. This then pushes the diaphragm back and allows the oil up tube [2] into the inlet-manifold. This is clear in my case by the wiring-connectors to the other end of tube [2] and the diff.-pressure sensor being filled up with oil past the metal prongs.

Stripped, the CCV looks like this. The diaphragm housing was completely jammed solid with oily crud, which had leaked round the whole housing. The spiral oil-seperator was clogged with oily rust, which took a lot of getting out. All items were soaked in brake-cleaner and left in the parts-basin at work, then the oil-seperator was blown through with 200psi from the airline. Eventually I got quite a lot of air-flow through the vortex and the diaphragm-housing was squeaky clean, so I threw it back together and refitted the CCV and manifold. I've saved £45 on the part and this quick-fix should work for enough time at least for me to rule the CCV out if the problem persists. If it goes and comes back, £45 is not a lot to spend and I will be glad to do so if it cures the low idle problem!

E46 318ci: The Beemer that chose me...

This is my new E46 coupe. I didn't intend to buy it, or even own it. It's a 51-plate 318ci SE with 133k on the clock. I have been seriously hankering after an E46, but this wasn't quite the Beemer switch I was after. The intention was to split it for parts... But once I've walked past it a couple of times on my drive I naturally realised it needed my help and decided to 'av a little go. It's turned into Beemer love beyond Beemer love...

Synopsis:

• No front bumper.
• Hole drilled in petrol-tank.
• No brake assistance whatsoever.
• Sticking calipers.
• Rotten wheel-arches.
• No driver's door-card, so no handle, speaker etc!
• No battery.
• Runs... Just.

E46: Vacuum-pump severe failure...

With a new servo and master-cylinder, but still no brake assistance, I decided the vacuum-pump must be leaking air. I whipped it off, only 3 bolts and no need to remove rocker-cover etc., and opened it up. This is what I found...

This chamber should be full of air, not oil. The pump bolts on to the back end of one camshaft, which turns a spinning-boss. A plastic-bar slides up and down in the spinning-boss and creates a constant vacuum into the servo to help 'suck' the brake-pedal down when you brake. My plastic bar is missing. Where is it? Well, it's smashed into pieces lying in the oil.

After a clean up it was a decent pump-body and would work fine with a new O-ring and plastic-bar. They sell O-ring kits for the N42 vac-pump separately, but plastic-bars they do not, so I bought the pump from the same donor car as the servo + M/C. All pieces seem to have sheared off with a clean break, the bar was literally blown apart, except for one of the round end-caps (the tiny piece in the middle of the pile in the photo). That had been spread into thin strips as it broke off, so it looks like that end contacted the side of the case, spread into fronds and jammed the plastic-bar, which promptly blew up. How though? Did the timing slip unbalance the camshaft enough to wreck the pump? Or did the plastic-bar break apart and jam the pump, causing the camshaft to stop briefly and the timing to slip in the first place? Hmm...

Another side effect of the vac-pump failing was a terrific oil leak. The O-ring seal had gone completely and the spinning-boss was acting like a mini oil-pump, sending a constant stream down the back of the head onto the hot exhaust [bottom of the pic]. The pressure also made the vacuum-hose connector, normally only filled with air, to leak at the jubilee clip and pour oil onto the gearbox-housing [middle of pic]. After removing the pump a huge third pool of oil arrived. This was what had run out of the vacuum-hose to the brake-servo after disconnecting.

E46 318ci: Total Jobs Checklist.

Sat 6.7.15:

6 months tax.

2 new front tyres.

4 new brake discs.

New master-cyl. / servo.

Fuel tank repair.

Replacement front bumper.

Sat 12.7.14:

• Re-bled brakes.
• Wynn's Engine Stop-Leak and half a litre oil.
• Rad-hose repair-tape kit, cable-tie out of way, 1 litre water/coolant.
• Cleaned wiring-connectors to cam-sensors.
• Cleared all oil residue from exhaust-manifold.

Quick run of engine with NO MAF connected gives improved idle-speed of 900rpm. After revving, it drops below 900 for a moment, then returns to 900.

Brakes are bled and still very stiff. No servo assistance is present, but the servo and m/c are known to be working. Could the problem be the vacuum pump? Could this be causing the oil leak?

If not, then it feels a little too low for the rocker-cover and will most likely be coming from the rear main-seal, which is a gearbox off job, so lets hope its just draining from one of the rear rocker-cover plugs and running down the head.

Tues 15.7.14:

Replace vacuum-pump.

Replace both camshaft-sensors.

Replace MAF sensor.

Remove inlet-manifold to check CCV and crank-sensor.

Clean oil and recondition inlet-manifold.

E46 318ci Brakes Checklist

Calipers pushing back fine, hoses not collapsed or clogged.

No fluid coming out of master cylinder itself, so brake pipes not clogged.

Fluid drains from the master-cylinder from the spout that joins to the hose that runs to the servo-housing.

Master cylinder no pressure? No visible leak.

Servo stopping master-cylinder from pressurising?

Pedal not operating?!