How to clean your EGR and manifold

[Parrot of Doom]

The car is still surging on startup on cold mornings, as well as the occasional rough idle - all goes away when warm. So I thought I'd clean the EGR system out a bit.

My car is a W210 with the OM606 TD engine (3.0 turbo diesel). The EGR system recirculates exhaust gasses to reduce emissions, but in recirculating gasses it also recirculates oil vapour and soot. Guess where the vapours and soot end up.....

The job should take about 3-4 hours.

Tools needed:

Good range of metric torx bits (and no I don't remember the sizes, you'll have to experiment!)
Extension tubes for your ratchet and sockets
Hammer/mallet
Engine degreaser - at least 5 litres
brush (for cleaning inside of manifold - chimney sweep type of brush)
Freeze release type spray
Selection of rags
A torch/flashlight

You may also need a new gasket for the manifold, although I made do with paste. Its also worthwhile having some spare bolts for the manifold, they're available from the dealers and don't cost a lot. There is an O-ring on one side of the EGR valve, you may need that although I didn't.

You will definitely require help from a friend for this job.

1. Drive the car up a couple of ramps. Remove the plastic undertray that protects the bottom of the engine (4*8mm bolts IIRC). Open the bonnet and let the engine cool down for 20 minutes or so. Have a brew.

2. Remove the black plastic cover from the top of the engine. It comes away easily, its mostly cosmetic in function. Put the cover down, and the bolts inside:

3. Next, remove the 12 manifold bolts from the cylinder head. They will be very very tight, so make absolutely sure that the torx bit you have is spot on the correct size. I don't know the exact size, but we found a key that fitted perfectly. They really do require serious strength to undo.

One of my bolts was broken when we came to remove the manifold. The last person to have worked on the car must have over-tightened it, and it snapped while in the head. There was another bolt as well that had a decent size chip on, somebody must have whacked it with a tool to get it moving.

It may help at this point to tap the bolts with a hammer. It just helps remove any corrosion between the bolts and the manifold, makes it a little bit easier to get it moving. Freeze spray is also useful here. Thankfully, all the bolts came out without issue.

4. Once the manifold bolts are out, turn your gaze over to the other end of the manifold. If you look carefully down the side, you should be able to make out a small clamp that holds one of the metal pipes to the EGR valve. The clamp is held in place by a single bolt. The clamp has a threaded hole, so there is no nut to risk losing. Its a poor photo, but here is the bolt:

Its just above centre of the image, alongside the body of the manifold.

Slacken that bolt off, but don't undo it completely. Its only to hold the clamp together, once the clamp is loose enough the pipe will come away from the valve easily. Be warned, that pipe isn't very flexible - don't try to bend it. It heads off around the back of the engine.

If you're unlucky, whoever did the clamp up the last time did it from the underside, in which case get the extension tubes out!

Theres a lack of pictures here because frankly I only have a phone camera and its easier to describe it than to take pictures. If you need technical references, here is a diagram:

There is a large metal bracket which holds the other pipe to the EGR valve. One end of the bracket is bolted to one of the engine shock absorbers, and is easily reachable. The other end of the bracket is trickier. There is a bolt which goes first through a small hole brazed onto the side of the pipe. The bolt then goes through a hole at the end of the bracket. The bolt finally screws directly into the body of the EGR valve. Therefore one end of the bracket is sandwiched between the pipe and the EGR valve. Remove this bolt - you have to do this from underneath the car. Its a bit tricky but you can reach it. This is where a spare pair of hands is welcome.

Once the bolt is out, there are another couple of bolts and a clamp for the rubber hoses that run nearby (but are unrelated).

Finally, you will see 2 vacuum hoses running to the body of the EGR valve. Just pull them off, no tools required.

Being watchful of the big black line that runs over the manifold, gently lift it out (it may require a bit of working side to side to free it from the pipes below).

The pipe on the right is the one that is clamped and unbolted from above. The pipe under the brake line is the one held by the metal bracket.

Here are the 2 vacuum hoses for the EGR valve:

You can't possibly get them mixed up. One goes to the left, the other to the right. Its easy, and they won't reach eachother anyway.

 

[Parrot of Doom]

Place a big towel over the inlets on the cylinder head, just in case you're tempted to drop anything in there. Small bits of dust won't hurt anything, but a bolt or a socket might! Also stuff a rag into both of the 2 pipes connected to the EGR, just in case something falls down in there.

5. Time to clean that manifold! You'll have already picked yourself up from the floor after noticing the extreme amounts of filth in the manifold, the cylinder head, and the 2 pipes to the EGR valve!

That oily paste is about 0.5 - 1mm thick!

Same story on the cylinder head, its filthy! You can also see some remains from the gasket.


The degreaser we used - well I don't know what its called. It was described to me as "don't leave this on your hands" which is good enough for me.

This is the inside of the EGR valve:

Its basically a spring-loaded piston. If you push one side of it very hard with the end of your ratchet, you can force it open. It requires a lot of strength, and you will again need the help of a friend to do this. I got my mate to push it open, and then used the engine degreaser and a toothbrush to give it a bit of a scrub.

Put the manifold on its back, and fill it to the brim with your degreaser. Leave it for a while to soak in to the muck.

7. While you're lieaving the degreaser to work its magic, run your fingernail down the inside of one of the inlets on the cylinder head.

That, is the crap accumulated behind one of my fingernails, after running it a mere inch down one of the inlets. Get as much as you can off using this method.

Once I'd got bored of doing that, I got some carb cleaner spray and squirted a very short burst of spray - 1/5 second into each inlet. I let it soak for a minute, then I got an extension from a ratchet, wrapped it in a towel, and shoved the towel into each inlet, scraping the muck from the sides. It takes ages to do this, the muck comes away easily but its so greasy and there is loads of it!

Once you've cleaned them all, and the face of the cylinder head (where the gasket goes), it should look a bit like this:

8. Have another brew. In fact, have 2, since the longer you leave the degreaser to work, the better it will work.

9. Get a brush into the manifold, and scrub away. Really really go at it, get all the muck you can out. Same with the EGR valve, scrub it spotless. Use whatever you can find to clean it out, we used a toothbrush. Swill it around, and when you're happy that enough has been removed, empty the degreaser (down the drain, naughty naughty). Run the manifold under a tap or a hose, make sure that its well and truly clean.

You're not going to get rid of all the crap, but you can get rid of a lot of it. You'll see it coming out with the degreaser. It looks a bit like this creature:

 

[Parrot of Doom]

10. Once you're certain the manifold is as clean as you can get it, apply your gasket paste to the gasket, the manifold, and the cylinder head. We used the blue stuff, it doesn't go hard and get into the engine like the red stuff.

Return the gasket to the manifold:

Refitting the manifold is now the reverse procedure of removing it. Its tricky to get the clamp for the smaller pipe in place, so again you'll need help.

Heres the snapped bolt we came across, alongside a complete bolt:

Fortunately a pair of pliers were able to be used to remove the threaded part from the cylinder head, so it was just a case of screwing in a fresh bolt bought from the dealer.

12. Once the manifold was back in place, I cleaned out the breather pipe that runs along the top of the injectors. Theres a small black plastic device that sits on top of the engine under the black plastic cover. I'm not certain what it does but I think it probably controls the vapours from the engine in some way. Its entirely passive. I noticed that one of the pipes that is connected to it, was split, so I put a jubilee clip around it and sorted it out:

I haven't had chance yet to see if theres any difference, but the next cold day will tell, when I see how the engine behaves in the morning. Its probably worthwhile giving your car a serious Italian tune-up before that grease and muck starts drying out again, so don't worry about the huge clouds of soot coming from the exhaust for a few miles

And thats that. Thanks for reading

Oh I should add that on mine, the bit of brazed metal that helps to holds the main pipe, the bracket, and the EGR valve together had broken - the head of the bolt had just moved clean through the hole where the break had occured. That meant that the lower pipe wasn't held in place by the bracket. So we got a big washer and sorted that. Something to look our for. You can see it in this photo:

http://homepage.ntlworld.com/tom.jef...gr valve.jpg

The hole on the pipe had broken, and was too big.

 

[Blobcat]

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