I don’t think this has been covered before, so I thought I would share my experience.

When I bought my 2003 there was a slight oil leak down the back of the engine, light mayo in the filler cap and on motorway journeys I would get a check engine light would come on when I lifted off the throttle to go down slip roads etc. The codes would generally be P1171 and 1174, sometimes variants on these.

Upon closer inspection the PCV (positive crankcase ventilation) hoses at the back of the engine had turned to mush and were letting normal air and moisture into the crankcase. When I did some research on the BMW forums, it seems this is a common problem that every BMW 4.4 will suffer from.

I replaced the hoses with oil resistant 2 ply radiator hose, rather than the BMW non oil resistant hose. If you replace the hoses with genuine parts they will disintegrate again after a few years, so best replace them with other hose. One end is a slightly larger diameter, soaking the hose in boiling water before fitting makes the rubber much more supple and happy to stretch.

All in all the replacement took me about an hour, if you’re short you’ll need to stand on a crate to get in there, but once you’ve taken the heater air intake out you have tons of room.

I would suggest you pop your acoustic cover off and just have a look/feel of the condition of the hoses. I have noticed since doing them the engine is quieter, smoother and gets better mpg! I think the replacement hose cost me £1.00 per meter from the motorfactors!

Anyway, see these pics for some sort of guidance as to what I’m talking about:


Heater filter housing removed:


You can see the hole in the hose, with mayo coming out:


Really soft hose:


The rest of the hose had collapsed completely:


Whole thing was like a soggy bit of paper:


Hope this is of help to someone, when I did it I was doing it blind. If anyone needs advice on the above, just post or pm!

Dan 

Excellent Dan, this is what these type of forums should have more of. Makes the price of ownership for the more mechanically adventurous a lot cheaper.

Dread to think how much a stealer would have charged to diagnose and fix that (relatively simple) fault.

We just need someone to buy Autologic or similar and give us all the benefit (at a discount of course) without having to pay dealers our hard earned wedge.

Larry wrote:

We just need someone to buy Autologic or similar and give us all the benefit (at a discount of course) without having to pay dealers our hard earned wedge.

Unless you want to edit settings, or read advanced codes for the EAS/SRS/HEVAC then I found a USB - OBD code reader is great. It reads the engine/trans codes and then looks it up in it's database and tells you what the problem is (allbeit usually the wrong description the code is always right)

Someone I know paid £300 to have this done, which for a couple of bits of hose and half an hour of labour in a garage environment is rediculous!

Like I said, it's definately worth checking yours out, if the vapours dont vent correctly you can get a build up of corrosive gasses in the crank case, or as mine did, it can draw moisture in and turn your oil gloopy! 

ive been meaning to have a look at mine for a while............ this is a great reminder, cheers!!!

Good shout mate, just checked mine and the LPG pipe running across the top had totally squashed it flat. Can't believe they put this sorry excuse of a pipe in looks to be made of sausage skin. Can only see the one end of the pipe at the moment not looked far enough down back of engine to see where other end goes, will investigate further.

Dan, any chance you could give me an idiots guide as to what parts to buy. I assume I will need a couple of jubilee clips and some pipe. Can you advise of pipe diameter to ask for...thanks Stevie

PS When I pulled my pipe it burst (no smut please) will it be OK to run for a while until i get a couple of days off to replace.

You will more than likely throw a code - but this will clear itself after you have replaced the hoses, you will probably also get poor idle when on petrol, LPG should be ok though as the LPG ECU ignores most sensors.

You need some 21mm internal diameter hose to do the two top hoses, but one end is bigger than the other and will need stretching in hot water, it sometimes helps to stick a screw driver handle in the end to widen it! Buy new jubilee clips for all hoses, get a couple extra too, just incase one strips the thread and you have to go out and get another mid job!

If you need to replace the small hose at the bottom of the cyclone, then you will need a piece of 8mm internal diameter hose. I didn't replace this because i didn't know it existed - only after looking at this diagram did I see it. I will replace mine when I have a little more time, but at the moment I think its fine, I will probably take the whole cyclone off and clean it out as its bound to be full of gunk.

The genuine hoses aren't massively expensive, £15- £20 each for the two main hoses, so you could buy these, but as I've already said you will get the same problem in a couple of years time.

Anyway, here is the exploded diagram of the whole PCV System, you want to replace 6759A & B and 6C342A:

Click image to enlarge

Thanks Dan, I'm 6'6" and can barely feel the other end of the hose down the back, may need to get a crate myself. Will wait until daylight and see how much of the clutter around the top i can remove to make room.

I'm guessing the smaller lower pipe is a pig to access.

Don't want to veer too far off topic but Dan had me panicked when I saw the pipe had perished and I reluctantly took my oil filler cap off, with one eye open praying there was no white sludge...huge sigh of relief just nice golden brown oil but I noticed small gold shavings of metal on the rubber seal on the cap. Initial inspection it looked like the alloy around the filler cap had corroded. Gingerly scraped it away trying not to let any fall into the timing chains...anyone else noticed this?

After 6 hours going round various motor factors found that 21mm internal diameter radiator hose is like hens teeth. Eventually went to a hydraulics company who gave me 22mm internal diameter hose, stuff is about 4mm thick and you could use it as a cosh. Removed old hose which was disintegrating in my hand.

Connected lower end to metal pipe at bottom of engine and it was a great fit, however when I tried to connect to the top end (plastic end on the top of the cyclone cylinder) found that the internal diameter of the pipe was far too big and also there was not enough clearance to get both it and a jubilee clip on. Ended up cutting the only decent section of the old hose out refitting it to the top of the cyclone and then buying a copper 22mm straight connector from B&Q and joining it to the new hose. Seems to work well.

After all this the 'check engine' light is still on.

Dan - should the light self extinguish if all is well or will I have to reset it with an OBD reader. OBD readers are also pretty scarce so i have ordered one from e-bay but it probably wont arrive for a few days yet. Worried that this was not the cause of the light coming on and apprehensive about using car until can be sure.


Will use this as a temporary fix and what I intend to do is source some good 19mm hose and connect it to the 22mm hose with a copper reducing plumbing connector.

Yeah the Cyclone is a larger diameter, by a couple of mm, but rad hose warmed up will usually stretch (hydraulic hose may not as it has to deal with higher pressures?)

Did you do both hoses?

I found my fault cleared after i changed the hoses and drove to the shop - on the next start up they had gone. If you have only done one hose you may still have a problem.

Dan 

Only did the top hose as it was in a sorry state, bonus being that the new hose is so robust it lifted the electrical connections off the lower hose and let me manipulate it back into shape to leave it unobstructed. I will replace the other hose when i figure out a way of joining two hoses of different diameter without the aid of B&Q (unfortunately they only do 15 and 22mm connectors).

Looking at silicone hose which come in a variety of diameters, expensive but might be worth it!

Might have to look at replacing the cyclone as it looked pretty bunged up, will investigate whether you can take it off and clean it or whether it is a cheap replacement item, no point in having good clean hoses if the PCV Cyclone is so clogged it doesnt pass any gas.

Thanks for the offer of the OBD reader, let me see how long mine takes to arrive, I had to buy a stand alone one as my laptop is goosed.

If you decide to go sillicone these guys are helpfull http://www.merlinmotorsport.co.uk/

Dan this is first class information. letters not necessarily in the right order

RE CYCLONE:

Yes you can remove the cyclone and clean it or relace it. If it has a filter in it it will be a metal gauze filter, but I dont think it does, the idea is it spins the gasses and the oil flings to the side and then runs back down into the sump.

There are two bolts that hold it and the bracket it is attatche to onto the engine:

Click image to enlarge

I found this info to supliment my post as the Workshop Manual is fairly vague on how the PCV system works:

Countless explosions occur every minute your engine runs. While the good majority of this internal combustion is confined to the combustion chambers, a small amount of the controlled explosion sneaks by the piston rings and creates blow-by gases inside the engine crankcase. These combustion by-products must be vented away for proper engine operation.

Positive Ventilation
Back in the days of environmental abandon, engines vented any crankcase gases and blow-by materials through a tube right out onto the ground. No valves required. As time and engineering improvements marched on, a simple system was devised to re-burn these gases and materials back through the engine for cleaner air. At the heart of this system is the PCV valve.

PCV is an acronym for positive crankcase ventilation. A PCV valve is only half of a two-part system. At one end of the system is a breather, which allows fresh air into the crankcase. At the other end of the system is the PCV valve itself, which meters spent gases and combustion by-products back through the engine relative to engine demand.

At idle the engine isn't working very hard and the valve remains mostly closed, allowing a small amount of the crankcase gases back through the engine. At full throttle the engine works harder and creates more crankcase gases, so the PCV valve opens wide to let more through. If the valve gets gummed up with gunk it won't meter properly.

When to Replace
If the PCV valve is stuck open at engine idle, too great a quantity of spent gases are let through. Rough engine idling and stalling can be the result. If the PCV is stuck closed, pressure inside the crankcase can build up and the gases can force engine oil up through the breather and air filter causing excessive oil consumption and a fouled intake system. The good news is that replacing the PCV valve is both easy and relatively inexpensive.

Since most PCV valves open and close by way of a spring and plunger, they should be checked or replaced approximately every 20,000 miles, or according to your vehicle's service schedule. Since a crucial part of proper PCV system operation is a positive seal, it's also a good idea to check all hoses, grommets and clamps when servicing the valve. Always replace cracked and leaking rubber and defective clamps when replacing the PCV valve.