So what is the EGR and why does it clog up? On the M57 engine the EGR valve is vacuum operated. When the car is idling or moving slowly the valve will remain shut, when moving at higher speeds and once the engine has warmed up, the valve will open, allowing a specified amount of exhaust gases to re-enter the intake manifold. The aim is to reduce the amount of harmful NOx gases being released to the atmosphere by way of lowing combustion temperatures.
Over time it becomes clogged up with carbon deposits from the exhaust gases and can seriously effect the running of the car. Rough idling, poor mpg and stalling at idle are all potentially symptoms of a bad EGR.
Without further adieu I set to work restoring my EGR valve. It's actually rather painless to remove; take the engine covers off, loosen clamp [3], undo all four bolts [11] securing the EGR to the intake manifold, pull the vacuum hose off and undo the hose clamp on the end of [6]. The EGR should then be free of the intake manifold, make sure you don't lose the rubber seal / gasket [4]. If you lose it, or you just want to replace it, the part number is 11612245439.
To avoid any unfortunate disasters, it's probably wise to block the intake manifold with a bung of paper towels to stop any foreign bodies getting in there.
Once off, the extent of the carbon build up could quite clearly be seen. Mine was pretty clogged, clearly the EGR couldn't be helping the performance of the engine any. However, this wasn't the worst example I'd seen, some of the horror stories on the net had shown build ups that had almost completely closed up. If yours is quite clearly damaged, you may wish to replace it at this point rather than clean it up, the part number is 11717804378 if you do.
I used a variety of products to clean the EGR, mostly because I didn't know what would be most effective. I started off using some white spirits and a small brush, but that was hard going. I switched to using a bath of petrol after a few minutes, which proved much more effective.
You need to make sure you don't get any fluids in the vacuum hose aperture though, so I blocked this off prior to cleaning.
Any areas I'd missed I sprayed directly with some Autoglym Engine Cleaner and agitated with a small brush. Some of the carbon build up came off fairly easily, but a lot of it was really baked on there.
Make no mistake, this is a slow, messy process but eventually the EGR was looking pretty respectable, as you can see below, quite an improvement.
For peace of mind, spending an hour or so cleaning up your EGR has got to be time well spent, and best of all it's cheap and easy to do.
Let me know what you think in the comments, have you cleaned yours? Any tips to shift the stubborn grime? Was yours worse than mine?
2 Comments
Great Blog Andy!
ReplyDeleteI'm on the same journey, my 2004 330d m sport tourer is providing me with a constant supply of tinkering. Only had it a month, my first bimmer.
The car is suffering from lack of power up to 2k rpm, then turbo spools up n all is well.
Can I ask you, when you cleaned your egr, how much pressure does it take to move the piston in? I had mine off and needed a vice to get it to move. I checked it with the intake hose removed, at idle, no movement at all.
This all started after I replaced the filthy air filter and replaced with a k&n. I found a fault code (p0401 egr insufficient flow) and removed the k&n. With a new oem filter fitted, nothing changed.
Removed and cleaned the maf, nothing changed.
I have just had the air intake manifold off, to get to the vacuum hoses. Found a couple perished and replaced em. First couple of miles seemed better, but then back to no power. Could be another hose leak somewhere else, I'm gonna have another look soon.
Any advise you could offer mate? I am determined to sort this myself, well with some divine guidance anyway!
Cheers for the super blog Andy, I have enjoyed reading through your memoirs, super quality!
I do hope you get time to update it, I expect you've done most jobs by now.
Take care mate.
Steve
Hi Steve,
DeleteThanks for leaving a message, apologies it's been a slight delay before a response.
I think my turbo kicks in around 1750rpm, after that it pulls like a train to about 4000rpm. Before 1750rpm there is turbo lag, so there might not be that much at fault on yours. However, it sounds like you are doing the right thing by checking and replacing the vacuum hoses, these are almost certainly the fault. Make sure you have checked all of them.
Check this link out, scroll down to Vacuum Control, RealOEM - Vacuum Control
As for moving the EGR valve, I can't remember exactly whether I got it to move or not, but I certainly had to use a flat head screw driver and leverage to get it to do anything if it moved. I've disconnected mine now anyway and have run it like that for over two years. There's a post on here about it if you haven't read it already.
Glad you've enjoyed the blog so far, there are definitely more posts to come, one is in the works at the moment. I just need to get the time to type them up!
Cheers,
Andy.
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