Where are sparkplugs on BMW e36 2.5?

Answer 1

Begin by prepping the car. The only thing that you really need to do is to make sure that the car is cold. If you try to remove or install spark plugs in a hot car, then you may encounter problems with the spark plugs gumming up or damaging the relatively delicate threads in the aluminum cylinder head. Just make sure that the car is cold, or at the bare minimum, only slightly warm to the touch.

Let's talk about the six cylinder cars first. The first step is to remove the top plastic covers from the engine. These serve no mechanical purpose - they are there only for decoration and to prevent dust and debris from getting into the recesses of the engine. On the six cylinder cars, there are two covers, a long thin one on the top of the car, and a wider one towards the left. Speaking of left, for the purpose of this particular tech article, I will refer to the left side of the engine as being on the left as you are standing in front of the car looking at the engine. The right side would, of course, be opposite to that. For reference, the windshield washer bottle would then be on the left, and the air filter would be on the right.

On the two plastic covers, there will be two small, snap-in plugs on the top. Carefully remove these plugs (don't drop them into the engine) with a small screwdriver, prying them up as you grab them. Underneath you will find a nut that holds the cover onto the top of the engine. Remove the four nuts on these two covers, and they should both simply slide up out of the way.

Underneath the left cover, you will see the six spark plug coils that sit on top of each of the plugs. You need to remove each of these carefully, in order to gain access to the plugs. Using a screwdriver, release each connector from each coil. There is a metal retaining ring on the rear of each one that fastens it to the coil. Once you lift up on the retaining clip, then the connector should simply slide out of the coil. Carefully remove all of the connectors from each coil, taking care not to bend the wire harness too much. These wires are stiff, and generally don't take well to being bent in multiple directions. Just be gentle with them.

To assist with your maneuvering of the wires, detach the center clip that holds the wires that come from the center channel. This clip is shown in. Gently place the wires off to the side and out of the way, without bending them terribly.

With the wires detached and placed slightly out of the way, you can now remove each of the six coils. Each coil is fastened to the valve cover using two screws. On two of the coils, there are two small ground straps that connect the coil to the stud on the cylinder head. Take note of these ground straps - they must be installed properly when you are finished, otherwise your car may encounter problems.

Remove each of the two nuts that hold each coil to the valve cover. At this point, the coil should be able to be easily pulled right off of the engine. The coil has a small coil pack on one end, and a spring-loaded spark plug connector on the opposite end. Simply remove the coil/plug assembly and place it off to the side. All of the coils are the same, so it doesn't matter which cylinder bank it came off of - unless you are specifically trying to troubleshoot a bad coil fault code that was displayed by the main computer.

With the coil removed, you should be able to look down the hole and see the spark plug hiding in there. However, as you remove the plugs, you may discover something peculiar. The way that the ignition system is designed on these BMWs, there is the opportunity for the spark plug holes to completely fill up with oil, if you have a leaky seal on your valve cover. When you pull out the spark plug connector / coil combo, you may find that it is completely submerged in engine oil,Looking down the hole, you may not even be able to see the spark plug because the entire hole is filled up with oil. While common sense says that this is not a good thing, the reality is that this is actually quite common, and doesn't seem to affect the performance of the car one bit. If you do find this oil in your spark plug holes, I would suggest that you go one step further and replace the valve cover gasket. This replacement procedure is very simple, once you have the coils removed, and should only take you about 20 minutes more, providing you have the actual gasket on hand. If you find oil in your spark plug holes, then you should definitely replace the gasket.

If you find that you have oil in your spark plug holes, I suggest that you take some paper towels and attempt to soak up as much of the oil as possible, before removing the spark plug. If you don't get rid of the excess oil, then it will leak into the cylinder head through the spark plug hole when you remove the spark plug. This will cause your car to run sooty when you first start it up, and it may even foul your brand new spark plugs that you just installed!

Spark plug removal is easy - you just need the right spark plug wrench. I have one that I love - it's a spark plug socket with a rubber insert that catches the plug. In addition, it has a built-in swivel on the attachment end. This is especially useful when trying to remove plugs in hard-to-reach places, as they are always located on Porsche engines (BMW engines aren't really that bad with respect to spark plug access).

Using a breaker bar, grip the plug and turn it counter-clockwise until it is loose. Then pull out your tool and grab the plug. When the plug comes out, you may want to take a close look at it. The spark plug is really the best way to visually 'see' what is going on inside your combustion chamber. You need to pull out all of the spark plugs to replace them, so you might as well take a close look at them while they're out. While today's modern fuels make plug-reading much more difficult, you can still glean a lot of information from looking at them. A good, well-balanced engine will produce a plug that is light brown in color, and dry. If the engine is running too rich, the plug will often be coated with a lot of extra carbon. Keep in mind that the rest of your combustion chamber probably looks the same. An engine running too lean will have a powdery white coating on it, and the outer porcelain ring may have a burned appearance.

When reading spark plugs, pay close attention to the white porcelain ring around the plug. This white area will give you an excellent background to inspect the color of the plug, and to help determine how your combustion chamber looks inside.

If the plug is wet with oil, then that indicates that there is significant leakage into the combustion chamber past either the valve guides or the piston rings. This is generally a bad sign, and an indicator that a future compression test may not yield good results.

With the new plugs installed and properly torqued, you can replace the coils and reattach the coil connectors. Snap the wires back into their center holders and replace the top two plastic covers. When you're done, your engine should look back to normal.

Changing plugs on the 318 4-cylinder cars is a bit different and a bit easier. You remove the spark plug cover in a similar manner. There should be a handy little blue spark plug wire pull tool under the cover. Use it to remove the plug wires from the ends of the spark plugs. With the wires disconnected, remove and reinstall the plugs in a similar manner to how I described the procedure for the six cylinder cars. You will also want to replace the spark plug wires every 30,000 miles or if they look cracked and worn out.