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.

BMW DPF cleaning - guerrilla style! [All Diesel BMW, F10 530d]

When your DPF is blocked and the car won't perform a re-gen, then chances are a good highway thrashing is not going to solve the problem any more and the DPF will have to come off to be properly cleared of clogged up soot. Replacements are outrageously expensive and professional cleaning is not cheap, plus the DPF must be sent away, but it is possible to do at home for very little money. You just need a suitable place to do it and be prepared for the mess...

A guide on removing the DPF for F10/F11 is here.

1. Compressed Air Blowout - This is the first step we took and may be all that is necessary if the DPF is not completely blocked. The only way I've seen so far with air compressed at enough pressure to clear stuff from the DPF is to use a 'bead-blaster' or 'bead-seater' designed for blowing tyres on wheel rims at about 90 psi. I doubt a tyre-shop is likely to let you use their equipment to blast a load of soot out of a DPF, as it is messy business, but if you know someone or have access to one then it's very effective. The DPF needs clearing out backwards, so secure it to the floor somehow (or get someone wearing ear-defenders to put their foot on it) and aim the bead-blaster into the flexi-pipe leading to the exhaust.

2. Cleaning Solution - This is a much deeper clean than just blowing the DPF out and will take a couple of days with it removed from the car.

• Seal the front end of the DPF as water-tight as possible. Re-fit the sensors to their holes and block off the small metal tube. Use thick plastic material to seal the large front opening of the DPF, tied tightly around the rim. Chances are it will still leak some liquid from around this aperture.
• Obtain suitable DPF cleaning-solution. I first used Wynn's Professional Off-Car DPF Cleaner, which cost me £27 for 5L. Quite pricey, but it certainly does the job. The Wynn's solution does smell very similar to a couple of cleaning products that were already available to me at work, both made by Autosmart, but I'm sure other companies make similar - TFR (Truck Film Remover), a strong de-greasing and cleaning solution, and G101, a very strong soap solution, so if you have access to these products it may be cheaper to get a few litres of each of them instead. I ended up using about 5 litres of neat TFR and the same amount of neat G101 after most of the Wynn's had leaked away and we have since cleaned out the DPF from an E81 120d, which worked a treat.
• Place the DPF in a bucket and leave the solution to soak into the DPF over at least 12, but preferably 24 hours. Even if it is impossible to stop fluid leaking from the DPF, the bucket will fill to a level where the pressure equals out and the DPF can be fully filled with solution as long as you have enough.
• Remove the plastic and jet-wash the DPF out from back to front, with the lance into the exhaust outlet. Be careful where you do this as it is very messy, with a lot of thick black soot being ejected, so try and do it directly down a drain as it cover a large area if done onto the ground. If you do not have access to a pressure-washer, then you could try flushing it with buckets of water poured in quickly, but this is not going to be as effective.
• Rinse the remaining soap from the DPF by leaving a hose to run through it and / or pouring buckets of water through. This will minimise the car 'blowing bubbles' once the DPF is refitted and still has soap / moisture inside!
• Leave the DPF to drain and dry out for as long as possible and refit it to the car.
• Give the car a 'spirited' highway drive, preferably in 3rd gear if it is manual, to blast remaining loose debris from the DPF. If the car was showing error codes for the DPF only and these have been reset, at this point the car should begin to re-gen by itself.

F10/F11: DPF Replacement / Removal - EASY GUIDE!

If you are removing your DPF and re-mapping, or if your filter is clogged past the point of a re-gen, then you will need take it off. Getting the DPF / catalytic-converter off an F10 is easier than it looks and is totally doable at home without a set of workshop ramps. I managed with a jack / axle-stand and without removing the exhaust or any of the engine.

1. Safely raise the car.

2. Under the car, remove the centre under-tray that covers the exhaust joint to the DPF by undoing a series of 8mm screws.

3. Loosen the collar-bolt at the joint between the front section of the exhaust and the flexi coming from the DPF using a 14mm socket.

4. Slide the exhaust back about an inch until it pops out of the sleeve in the DPF. [It may help here to pop the exhaust out of the centre rubber-hanger to give more rearward movement.]

5. Under the bonnet, unplug the two O2-sensors and the Lambda sensor, then pull the hose off the metal-tube that runs to the pressure-sensor. Free up the wiring.

6. Remove the upward-facing O2-sensor using a 14mm open-ended wrench.

** Access to the bolts and sensors may be easier with the plastic air-inlet loosened and moved out of the way. **

7. Loosen the collar-bolt joining the front of the DPF to the back of the turbo using a 13mm socket on a long extension and move the collar forward away from the DPF.

8. Remove the upper nut and lower bolt holding the bracket to the rear of the DPF using a 13mm wrench.

9. Remove the two bolts holding the bracket to the back of the engine-block using an E10 double-hex socket, or an 8mm ring-spanner and fully remove the bracket.

10. The DPF will likely be solid in place, so the best bet is to wiggle it from underneath car until it breaks free and can be safely lowered down.

11. With the DPF free, getting it out of the engine-bay is still not a walk in the park. The lower O2 sensor and/or Lambda sensor may need to be removed to get the angle required to slide the body of the DPF down past the steering-knuckle and foil heat shield, which may need to pressed in towards the body a bit to give enough clearance. Eventually, the DPF can be manipulated down through the gap and drop down under the car, so watch out if you have it raised a fair bit off the ground.

12. Re-fitting is a reverse of the above steps. Note, all but the lower O2-sensor should be fitted after the DPF is secured in position. The easiest way to reposition the DPF is get someone to hold it from below high enough for you to get hold of it from inside the engine-bay and lift it up into position, rather than one person trying to reposition it from underneath.