Leaking Valve Covers is a common problem for all 6 and 8 cylinder E39 BMWs. This DIY covers the M62 V8 engines of the E39 540i and 535i.The 6 cylinder engines follow a similar method but have specific instructions. The cause of the leak is that the rubber that the gasket is made from ages and hardens, and stops being able to seal between the head and valve cover. The solution is simple : replace the gasket correctly and the oil will stop leaking. Detecting the issue is simple – usually it manifests as an oil drip onto the garage floor and an obvious ‘hot oil’ smell when the car is parked after use. E39 engines do not leak oil when all gaskets are in good order and they should not smell oily. However, an oil leak can come from anywhere – so you need to visually confirm the leak is the valve cover gaskets. This is easily done by checking the surface of the head on the side and lower surface above the exhaust heat shields. You’ll see evidence of oil leaks, and the oil will pool in the engine mounts and on the undertray/splash shield.
In the above image you can see evidence of leaking oil at the lower part of the head/cover interface. You can also see oil leaking and running down the channels and there will often be signs of oil around the rubber sealing grommets for the holding nuts.
The vehicle in question here is also showing a classic M62 V8 problem of flaking point on the valve covers. Getting the valve covers refinished is ideal while replacing the gaskets.
It might be tempting to ignore this problem – however it should be addressed because the leaking oil will almost certainly be surrounding the spark plus, onto the engine mounts and suspension components and degrading other components. And nobody likes a car that leaves oil stains on the drive!
Parts and Tools
For this repair you’ll need a valve cover gasket set and 22 rubber grommets for the nuts that hold down the covers.
You’ll need some RTV sealant to seal the gasket down. I used Permatex ‘Copper’ because I had some on the shelf already.
It’s also an ideal time to change the spark plugs, so it’s a good idea to get a set of those if you haven’t changed them recently.
Finally, you should do this combined with an oil change, so 6.5 litres of quality synthetic oil and a filter are the final items.
The tools you need will be:
- 10 mm socket and open-end wrench
- socket drive, extensions and a universal joint
- spark plug removal tool
- small pick & mechanics mirror
- small screwdriver
- plenty of rags, paper towels, degreaser and brake/parts cleaner
- torx driver set
- paint protectors to prevent damage to the body work on the front of the car. You’ll be leaning into the engine bay a lot. I just use some old towels laid over the sides.
It’s a good idea to work on one side at a time. The left hand side is more difficult to do on an E39 due to the hard fuel lines that restrict space. You should choose whether you want to start with the easy (right hand) side, or dive straight into the more difficult side. The process is the same for both sides, but removing the cover can be a little more difficult on the right hand side.
Make sure you keep each piece of hardware removed – there are a lot of nuts, washers and fasteners. I recommend using a resealable bag for each side to keep the items separated. If you drop something (and you probably will) take the time to retrieve it before moving on, as you won’t be able to finish the job if you’re missing a crucial nut or washer.
Step 1 : Remove Components to create space
It’s important to get enough space to get in and around the valve covers. To do this, first remove the engine cover by pushing down on the 4 buttons and lift the cover straight up and off.
Next, remove the two round fresh-air ducts that feed from the cabin air filters (microfilters) into the cabin. This is done by releasing the seal between the cabin filter housing, then holding the duct with two hands and rotating towards the centre of the car (upward from the suspension towers). This releases the duct and it will pull out and upwards.
Finally, remove the air filter housing by releasing the clips. Also remove the Mass Air Flow sensor housing by releasing the large hose clamp – no need to pull it out of the car, just move it out of the way.
Removing these components gives access to the valve covers and makes the job easier.
Step 2 : Remove the Coils Cover
Each side has a plastic cover which protects the coils on each plug. These are easily removed by inserting a small screwdriver and lifting off the small (1 inch square) bolt head covers. Remove the 10mm retaining bolt and lift the plastic cover off. This will reveal the coils and the connections to the injector wiring box.
Step 3 : Remove Injector/Coils wiring box and Coils
The connections box needs to be lifted up to allow the valve cover to be removed. There are several things that hold the box down – the connectors for the coil packs, the connectors to the fuel injectors, and the two 10mm nuts on the top of the box.
First, release the coil connectors by lifting up the metal clips (toward the suspension tower) – the slide clips on the side will release the connector and it can be lifted up.
In the above image the first clip has been released, and the second has the clip undone but not yet released. Undo all 4 clips.
This will allow the coil packs to be removed by undoing the 2x10 mm nuts per coil. They will lift straight out. I always keep things in the order they came out, so I lay the coils out in the order they are installed. You can also mark them with a pen or tape to mark the order of removal/reinstall.
At this point you’ll determine how much of an oil leaking problem you have. The internal gasket around the spark plug wells will fail at the same time as the external gasket, and the spark plug wells fill with oil. You can see how the rear two coils are showing oil ingress - this is because the engine leans slightly backward so the rear wells fill with oil first. The amount of oil on each will tell you how bad your problem is.
Here is close-up of the spark plug wells showing the oil sitting inside. This is not good because it surrounds the spark plug and can interfere with correct firing, and oil can leak past the spark plug threads into the combustion chamber. The oil will eventually bake onto the heads leaving a tar-like mess.
The next part is where a lot of people run into trouble. The injector/coil wiring box must be lifted up to allow the removal of the valve cover. To do this, the box needs to be lifted off the top of the fuel injectors, which are on top of the engine. Each injector plug has a wire clip which holds it to the injector itself (injectors are red, plug is black). Using a pick or small screwdriver, unhook one side of the clip and push it down the side of the plug. This will release the plug without the wire clip falling off.
This photo shows the box undone and the injector clips on the plugs are visible, pushed to the side allowing them to be released from the injector.
This is one of those tasks where the right tool is going to make all the difference. I also recommend using a light and a mechanics mirror so you can see under the wiring box. When all 4 injectors are unclipped, undo the nuts holding the box down and pull gently upwards until the injectors release. You will not be able to remove the box because of the other wiring, but it should be loose enough that you can move it about.
Undo the two torx bolts holding down the positive jumper terminal on the left hand side – this will also give some slack in the wiring. In these pictures I removed the top of the wiring box to try and get more room to work with, but this was pointless so I recommend keeping the box lid on as it keeps the wiring tidy, and it’s one less thing to break.
Step 4 : Remove Valve Cover
Now you’re ready to remove the cover. Unfasten the 11 bolts holding the cover on, and be careful to keep all 11 bolts and washers. The rubber washers are not important as you’ll be replacing them, but don’t drop them somewhere and forget about it.
In these photos, I didn’t cover the wiring box – but it is covered in dirt. Before removing the cover I recommend wrapping the wiring box in a plastic bag, or carefully cleaning. If it’s not wrapped or cleaned, when removing the cover, a lot of dirt and gunk is going to dislodge and fall directly onto the camshafts and cam followers. You wouldn’t throw a handful of dirt into the top of your motor, but that’s effectively what happens when you take the valve covers off with a dirty wiring box.
Once all the fasteners have been removed, it’s unlikely that the cover will lift straight off. DO NOT use a pry tool to try and pry the cover off – the head is soft and the front timing chain cover is even softer. First start with a rubber mallet and give some taps around the edges of the cover, trying to get to the cover to move laterally. If this does not work, try using a metal (or plastic) scraper, and put it in the middle of the rubber gasket, and gently tap with a hammer. Keep any metal tools clear of the sealing surfaces. The seal seats in a groove in the cover, and the gasket is more likely to release from the head surface than out of the cover.
Once it pops off, feed the cover forwards and up to remove it from under the wiring box and the wiring leading to the positive jumper terminal.
With the covers off, you’ll be able to see the oil around the plugs better. And it needs to come out!
Step 5 : Soak up oil from Spark Plug wells
You will need to remove all of the oil in the spark plug wells. The best method is to take a paper towel and loosely roll it up and flatten it. Then push the rolled-up paper towel into the spark plug well, and use a small screwdriver to push it down. Leave it for a while then pull out the paper towel – it should be sodden with oil. Repeat with as many paper towels as needed to soak up the oil. You should keep going until the spark plug wells are clean – and the other nooks and crannies in the top of the head that are filled with oil. Be warned – this is a tedious job.
Step 6 : Repeat for the other side
Once all the oil is soaked up you can move to the other cylinder bank. It is the same process with very few differences. As stated already, it’s easier to remove the right hand side than the left hand side due to the greater freedom of movement. You should end up with two covers removed, the old gaskets removed and the oil from the plug wells soaked up and cleaned up.
The picture above is the right hand side before cleaning up. Note the flakes of paint and dirt from removing the cover on the camshafts and followers. Also note the black sealant on the sides of the join between the head and the timing chain covers. All of this needs to be cleaned up on both sides. Generally the remaining sealant from the gasket will come up with a gentle rubbing with a soft cloth. Use some thinners or gasket remover if necessary, but DO NOT use a steel scraping tool. Go all the way around the sealing surface and clean up the left over oil, sealant and flakes of paint.
I used a soft brush dipped in fresh engine oil to wipe up all the bits of dirt and flaking paint that fell into the valve train. You won’t be able to clean all of this, but you definitely don’t want your camshaft lobes crushing dirt and paint flakes into the cam followers. You can note the clean condition of the the valve train in this photo – with no sludge and only minor discoloration after 18 years of service – the benefits of running high quality synthetic oil with regular changes as per the manufacturers recommendations. I have seen some dirty and sludged up looking M62 valvetrains on the internet – this can only be from poor quality oil coupled with infrequent changes.
Step 6 : Replacing Spark Plugs
At this point you can now change the sparkplugs on both sides. It’s much better to change the plugs while the covers are off. Strictly speaking this is not necessary but it’s a good time to do this job with the covers off. Check your service records and calculate when the next plug change is due,
I use a spark plug removal socket, with a universal joint and an extension. Once the tightness is broken on the plug, it should be easy to wind out by hand – especially if the threads are well lubricated with oil. Check each spark plug as it is removed for condition. It’s a good idea to label them with the cylinder number they came out of, so you can look at them carefully after changing. You want to see nice grey/brown plugs with no evidence of oil burning, overly-lean ignition or physical damage. Reading plugs is a whole article in itself, but it doesn’t hurt to read up on it and do some amateur analysis on how your engine is running.
Insert the new plugs by carefully clipping them into the spark plug removal tool, and use your fingers to seat and thread the plugs. If you use your fingers to start, you’re much less likely to cross-thread the plug in the head. Remember the head is soft alloy and the plug is hard steel, so cross threading is a risk and a major bad thing. Generally you can torque down the plugs by doing them up finger tight, then adding another 1/2 to 1/3rd turn. Don’t over torque the plugs, but don’t leave them loose either. The plug box should show the maximum torque value.
Step 7 : Fit the Valve Cover Gaskets
You should clean out the groove of the underside of the valve cover (inner and outer) to make sure that there is no old sealant or flaking paint. The underside of the valve cover is not a machined surface so you can use a scraper to clean it up. BMW obviously doesn’t machine finish the part because of the groove-in-seal design which keeps the oil from escaping, even on the lower side of the covers, which presumably receives the most oil splash when the engine is in operation.
BMW recommends using Glycerin to lubricate the seals in the grooves so that they do not bunch or stretch when installed. I used a tiny bit of fresh engine oil, by dipping my finger in the oil and rubbing it along the seal that slips into the groove of the valve cover. My experience shows that the more you lubricate the seal, the harder it is to install because the seal will keep flopping out of the groove when trying to maneuver the valve cover back into place. I recommend lubricating very sparingly. You should push the seal into place rather than running your finger along the seal – start with the corners and push downwards – it should fit snugly. Don’t forget the seal for the spark plug wells.
Prepare for reinstalling by getting a helper to assist with holding the wiring box and various other wires out of the way, or you can do what I did and use an elastic strap hooked from the opposite strut mount, around the wiring box and back again. This holds the wiring up with mild tension and helps to get the valve cover underneath without needing a separate pair of hands.
BMW states in the technical instructions that you need to add sealant to the join between the timing chain cover and the head, and on the rear of the head where the ‘half moon’ sections at the end of the camshafts are. Squeeze a little sealant into these locations and spread out evenly. Honestly a finger is the best tool for use in this situation.
There are two ways of doing this – the first way is to maneuver the valve cover (with gasket seals installed) into the correct location, but sitting 10-15 mm above it’s seated position, and then apply the sealant. This has the advantage of giving you time to get the valve cover on, but is much more difficult to apply the sealant correctly as you will need to reach around the back of the motor to the half-moon sections and get the sealant in. It is also very difficult to apply the sealant to the lower side of the head/timing chain cover join as the covers block access once in place.
The second way is to apply the sealant in the correct places and then put the cover on. The advantage with this is that you can get the sealant correct. The disadvantage is that it means you have to hurry with the cover replacement before the sealant sets, and it’s easy to get the sealant everywhere while trying to stuff the covers back into place.
On balance I would recommend the second method, with perhaps a test fitment of the valve covers to get the feel for the best method on how to do it.
The above picture shows the right hand side prepared with sealant on the ‘half moon’ covers. In the upper right of this picture (and slightly out of focus) is the hard fuel lines which make replacement of the cover extremely troublesome.
This picture shows the sealant applied to the timing chain cover/head join.
When fitting the covers, do it slowly and methodically, and keep checking that the gasket seal has not fallen out of the groove in the cover. On the right hand side, you need to come in at an angle and get the corner of the cover under the fuel line while gradually moving the rest into place. The round part of the seal that fits into the half moon cutout is likely to foul on the camshaft caps and drag the seal out. I have read of people using dental floss to tie the seal to the cover – in the end I used a couple of small cable ties daisy chained together through the bolt holes and around the seal. I also had to stick a finger in through the half moon to fetch the matching rubber part of the seal. Once it was in place I cut the cable ties and carefully pulled them through, leaving the seal in place. Firmly locate it by adding the nut, washer and rubber washer into one of the center holes near the spark plugs, and the center hole at the front of the head.
I then used my mechanics mirror to go around every single part of the seal to make sure that it wasn’t twisted, pinched, pulled or generally not in the right place. At this point I just used firm pressure from my hand as well as the two nuts I had partially screwed in. This was to check that everything was correct before starting to torque down the cover.
Each nut is a combination of large washer, nut and rubber grommet/washer. Be sure to put the rubber washers in the right way around so they fit into the holes in the cover snugly. Screw down the nuts in a star pattern but do not torque down fully – get all nuts in place to the point where you start to feel resistance.
At this point I can tell you that the torque value is 10nm (not 10 ft/lb!). DO NOT GET OUT YOUR TORQUE WRENCH! Unless you have a very small torque wrench, this will be at the very bottom limit of what it can measure, and a regular wrench will generate a ‘burst’ of 2 or 3 times the necessary torque with the long handle. If you don’t believe me, do an internet search on ‘broken valve cover studs bmw’ and see the endless tales of people over-torqueing the nuts and breaking the studs. If you look at the design of the nuts, washers and rubber washers you can see they are designed to exert a set pressure and no more – over tightening just binds the stud into the end of the nut and eventually breaks the stud. 10nm is a ‘two finger’ tighten – on a regular size wrench or small socket handle – don’t use more than two fingers to tighten. You will feel it start to resist as you reach the end of the threads, the rubber washer will bulge slightly – at this point stop and resist all urges to give it that final tug for good luck.
When finished, do another final check for the seal seating properly around the perimeter and interior of the valve cover. You should see a nice even gap of the cover to the head, no grabbing or pinching, and definitely no bits of seals bulging out.
Step 8 : Refit Coils, Injector Plugs and wiring
Once the covers are back in place, refit the coils remembering to add the grounding wires to the third coil stud. Tighten down the coils – before you add the wiring back into the clips, refit the rubber gasket which seals the plastic coil cover. If you forget this you’ll have to take the coils out again to get it on.
Make sure you have the injector clips ready so that you just have to push the clip back over the edge to refasten. Push the injector box down gently making sure all the plugs are lined up and click in together. Then take a pick or small screwdriver and push the clips so that they click into place and the injectors are properly fastened. Refit the nuts on the top of the box and make sure that all the seals for the wiring are in place correctly.
The final injector clip is different and is on a wire, and uses a push-fasten clip instead of the separate clips of the other injectors.
Fasten the clips for the coil plugs making sure they click into place and are finished correctly. Fit the rubber grommets over the rubber coil cover gasket, then fit the plastic coil cover and put the two 10 mm bolts into the holes, tighten up and refit the two small square plastic covers.
Fit the oil cap, tighten down the positive jumper terminal and refit the main engine cover – the gaskets are replaced!
Step 9 : Change the Oil
After the gaskets have been replaced you need to start the engine up and let it idle for a while. Check carefully around all the sealing surfaces to ensure that oil is not leaking anywhere. The engine should be idling smoothly without problems. Also check under the car for any tell-tale drips making their way to the floor, and make sure the oil pressure light goes out as normal.
You need to let the engine get up to temperature, so it’s a good time to get out the degreaser and wash off some of the old oil leakage mess while the engine is warming up. The oil will be all around the heads, on the chassis rails, in the engine mounts, basically everywhere.
Once the engine is nice and hot, switch it off and undo the sump drain plug, with a suitable container underneath the car. Lots of people say you need to jack the car to change the oil but I never do – I just slide the oil change pan underneath, undo the 17 mm drain plug and drain the oil with the car on the ground.
Undo the oil filter housing and remove the filter carefully, wiping up any drops as they occur. Put in a new filter, including a new o-ring on the filter housing. Tighten the housing to spec (25 nm) – use a properly sized wrench or socket. Once the oil has completely stopped draining, fit a new copper washer to the sump plug and refit that, and torque to spec. Refill with 6.5 litres of fresh engine oil. Let the oil settle and then check the level on the dipstick, ensuring that it just meets the top mark.
After that, the job is done! Remember to dispose of the used oil at a local recycling centre – some shops take in old oil, and some local governments have used oil collection centres.
The tough parts of this job are removing and reinstalling the injector clips. The key to success is preparation, understanding what has to happen and using the right tools. When the clips are in the right position, and with the right tool, they clip in/out easily. The really tough part is fitting the valve cover back under the hard fuel lines on the right hand side. There is nothing for it but carefully jiggling and feeding it in.
While the engine parts are off, it’s a good idea to give them a good clean. Using degreaser and some plastic trim rejuvenator, you can get some shine back into the plastic parts. The Valve Covers themselves can be refinished. The end result is a dirty, dusty, ugly looking engine can be transformed back into something that looks good when the lid is up!
Before –dusty, dirty, oily, paint flaking – a mess
After – cleaned, refinished, degreased, shining!
Happy Solo Wrenching!