Jazz_89
02-14-2016, 02:48 PM
Alright everyone, time for spark plug replacement on the 535i E34 (first time for me). I am not an expert, but a few tips and the pictures might be helpful.
Here are the tools you need:
8413
The sockets are 21mm. Only use the correct spark plugs for the engine (Bosch W8LCR in this case). The garden hose is a good tool for this job ;) Required time: 2-4 hours depending on experience.
I heard that you should work only when the engine has completely cooled down and that you should not use anti-seize on the plugs, so I followed this advice.
The gap should be between 0.7mm and 0.8mm for these particular spark plugs, but it depends on the model I guess. Mine are Bosch W8LCR. It is probably a good idea to widen the gap a little bit, but I am not an expert on this. There is an extra tool for this job, but mine were approx. 0.7mm to 0.75mm wide so I did not change anything.
Start by removing the air filter cover and then the air filter box itself ( sorry that it looks so rusty and dusty :) ):
8414
Unplug the HT-Leads one at a time. Try to pull them out from the base, as close to the engine block as possible. Make sure that the key is NOT in the ignition.
Here is the spark plug on cylinder #1:
8415
Add some WD40 and then wait for a while for it to sink in. Carefully try to remove the plug with the spark plug tool (the one with the black handle). If it doesn't work try to tighten it a little bit and then try to loosen it again with small movements. I also had to use the torque wrench to remove a few of the plugs. Be very gentle in order to prevent cross-threading the spark. (actually I have the bad feeling that at cylinder #6 I almost cross-threaded the plug, because I could not tighten it correctly with the torque wrench :/ ). Try to listen for grinding or squealing sounds while you turn it out.
When you remove it compare it with new new for thread size, thread length, and make sure it is the same type. Also check if the washer rings are there. The last thing you want to happen is the piston to slam against the plugs because you used the wrong ones.
Then use a small 1/2" inch garden hose to insert the new spark plug. Like this:
8416
The garden hose will act as an universal joint and make the replacement process easier.
According to the manufacturer and various manuals, these spark plugs should be tightened with 28-30 Nm. After getting them in the head with the garden hose, I turned them with the spark plug tool until they seated and then used the torque wrench, first with 10Nm, then with 20Nm and finally with 30Nm, always looking and hearing for signs of cross threading. Make sure the torque wrench is exactly perpendicular to the plug when you torque it. This is the most critical part IMO. Before moving to the next cylinder reconnect the cable. Do not screw the firing order or you will damage the engine.
Repeat the process for the cylinder #2, #3... until #6. The last three, at the rear of the engine are tricky to remove. Removing the ignition coil from its attachment point, may provide some extra space, but be careful to not touch any high tension cables under any circumstances.
Here is the plug hole for cylinder #6:
8417
This is probably the hardest to install since the space is very limited. The thread appeared to be slightly damaged, since I torqued the plug with 30 Nm but then it kept rotating under slight force...:/
Here are the old plugs. In my opinion they look pretty descent:
8418
Any help on how to diagnose these? (the shining liquid is only WD40 I think) :
8419
Cylinder #1
8420
Cylinder #2
8421
Cylinder #3
8422
Cylinder #4
8423
Cylinder #5
8424
Cylinder #6
Here are the tools you need:
8413
The sockets are 21mm. Only use the correct spark plugs for the engine (Bosch W8LCR in this case). The garden hose is a good tool for this job ;) Required time: 2-4 hours depending on experience.
I heard that you should work only when the engine has completely cooled down and that you should not use anti-seize on the plugs, so I followed this advice.
The gap should be between 0.7mm and 0.8mm for these particular spark plugs, but it depends on the model I guess. Mine are Bosch W8LCR. It is probably a good idea to widen the gap a little bit, but I am not an expert on this. There is an extra tool for this job, but mine were approx. 0.7mm to 0.75mm wide so I did not change anything.
Start by removing the air filter cover and then the air filter box itself ( sorry that it looks so rusty and dusty :) ):
8414
Unplug the HT-Leads one at a time. Try to pull them out from the base, as close to the engine block as possible. Make sure that the key is NOT in the ignition.
Here is the spark plug on cylinder #1:
8415
Add some WD40 and then wait for a while for it to sink in. Carefully try to remove the plug with the spark plug tool (the one with the black handle). If it doesn't work try to tighten it a little bit and then try to loosen it again with small movements. I also had to use the torque wrench to remove a few of the plugs. Be very gentle in order to prevent cross-threading the spark. (actually I have the bad feeling that at cylinder #6 I almost cross-threaded the plug, because I could not tighten it correctly with the torque wrench :/ ). Try to listen for grinding or squealing sounds while you turn it out.
When you remove it compare it with new new for thread size, thread length, and make sure it is the same type. Also check if the washer rings are there. The last thing you want to happen is the piston to slam against the plugs because you used the wrong ones.
Then use a small 1/2" inch garden hose to insert the new spark plug. Like this:
8416
The garden hose will act as an universal joint and make the replacement process easier.
According to the manufacturer and various manuals, these spark plugs should be tightened with 28-30 Nm. After getting them in the head with the garden hose, I turned them with the spark plug tool until they seated and then used the torque wrench, first with 10Nm, then with 20Nm and finally with 30Nm, always looking and hearing for signs of cross threading. Make sure the torque wrench is exactly perpendicular to the plug when you torque it. This is the most critical part IMO. Before moving to the next cylinder reconnect the cable. Do not screw the firing order or you will damage the engine.
Repeat the process for the cylinder #2, #3... until #6. The last three, at the rear of the engine are tricky to remove. Removing the ignition coil from its attachment point, may provide some extra space, but be careful to not touch any high tension cables under any circumstances.
Here is the plug hole for cylinder #6:
8417
This is probably the hardest to install since the space is very limited. The thread appeared to be slightly damaged, since I torqued the plug with 30 Nm but then it kept rotating under slight force...:/
Here are the old plugs. In my opinion they look pretty descent:
8418
Any help on how to diagnose these? (the shining liquid is only WD40 I think) :
8419
Cylinder #1
8420
Cylinder #2
8421
Cylinder #3
8422
Cylinder #4
8423
Cylinder #5
8424
Cylinder #6