[GB-335xiCoupe]

I changed my spark plugs the other day for the first time since buying this car in August 2013. I tried some non-oem plugs, and ended up putting the originals back in but that's another post. I noticed two things in this process which concern me a lot.

In #2, there was a thick sludge, looking like black river mud at the bottom curve of the bottom of the spark plug well. I wanted to clean it, but didn't want any of it to fall down into the engine. So I left it, figuring it was benign where it was sitting.

This is a pic of #1, which has a little sludge, but not nearly as much as #2. I forgot to take a pic of #2 when I had it out, but I will when I finally get my new BOSCH plugs delivered... Sorry for the photo quality, but cameras don't like to focus on 3 planes.


The coil from cylinder 1 looked ok, just had some brown powder like dirt on the rubber tube. #3 has some sludge in the well, although much less than #2. #4 had some chalky white residue at the bottom. I wasn't too concerned. #5 and 6 wells seemed clean.

But, in #4, the coil looked like this:

and the other side



I am concerned. I can only think that this would occur if water had gotten into the engine, like in a flood situation. Can a coil rust like this under normal conditions? Or did something happen to my car before I bought it?

Is there any particular part on the car that I could inspect that would be hard to clean if someone was trying to cover up a flood damaged car?

[thomas88162]

It looks like water got in your wells. This could be from something like flood damage, but it could have also been a careless PO washing his engine bay.

[bamboostk86]

where is it from???

[GB-335xiCoupe]

Originally Posted by bamboostk86

where is it from???

Where is what from? The ignition coils are from my N55 engine. The car was previously owned in Chicago (one owner). CARFAX is clean. I'm thinking there's gotta be somewhere on this car I can look and see a clear indication of flood damage. Inside is clean though, and no signs I saw inside the trunk.

[07lilredwagon]

probably from overwashing the engine bay....oil in the plug holes may or may not indicate a leaking valve cover gasket?

JP

[Efthreeoh]

When I first looked at this post I couldn't understand how any rust could form because the coils are plastic-bodied on the N52 and the head is aluminum. Looking at it again and realizing the engine is a N54, I guess the coil bodies are steel (hence the red iron oxide). The N54 head is aluminum, so I'd say it is a classic case of galvanic reaction causing the corrosion, not water. But what I can't understand is all the trouble BMW goes through to use aluminum bolts throughout the N52/54 engine, why would they choose the coil bodies to be steel? Are those OE coils?

[GB-335xiCoupe]

Originally Posted by Efthreeoh

When I first looked at this post I couldn't understand how any rust could form because the coils are plastic-bodied on the N52 and the head is aluminum. Looking at it again and realizing the engine is a N54, I guess the coil bodies are steel (hence the red iron oxide). The N54 head is aluminum, so I'd say it is a classic case of galvanic reaction causing the corrosion, not water. But what I can't understand is all the trouble BMW goes through to use aluminum bolts throughout the N52/54 engine, why would they choose the coil bodies to be steel? Are those OE coils?

This is an N55 engine. Most of the coils had zero rust... this one I took pictures of was the worst. Two others had just a little bit of rust on them. The location of the rust on the coils indicates to me that there was water in this engine at some point, because the rust is present in highest concentration, where water would cling to the surface due to capillary action...

[Efthreeoh]

Originally Posted by GB-335xiCoupe

This is an N55 engine. Most of the coils had zero rust... this one I took pictures of was the worst. Two others had just a little bit of rust on them. The location of the rust on the coils indicates to me that there was water in this engine at some point, because the rust is present in highest concentration, where water would cling to the surface due to capillary action...

The N55 and N54 both use aluminum for the head and probably use a similar coil design, so what I said is still accurate. Regardless, I doubt the water is from a flood. For water to have enough pressure to get through the seal on top of the coil (they seal pretty good), the rest of the car would have been fully flooded and most of the electronics would be trashed, the engine would have been full of water where the valves were open to allow entry of the water into the cylinder, and the car would have a salvaged title. And I don't see how "over washing" the engine bay would get water in the sparkplug access hole unless the engine cover was off and water was sprayed at high pressure on the engine (then I'd look at the connectors for the coils, fuel injectors, and O2 sensors for corrosion too). With the engine cover on, I just don't see water getting past the coil seal and into the sparkplug access hole.

So it is either simply galvanic reaction of dissimilar metals or just plain old condensation causing the rust.

[bamboostk86]

Originally Posted by GB-335xiCoupe

Where is what from? The ignition coils are from my N55 engine. The car was previously owned in Chicago (one owner). CARFAX is clean. I'm thinking there's gotta be somewhere on this car I can look and see a clear indication of flood damage. Inside is clean though, and no signs I saw inside the trunk.

Well i guees you answered your own question cause apparently you knew what i was asking. if you dont see any other evidence i would lean toward an engine shampoo done before you purchased to pretty it up.

[MyF15+F85]

I have seen the same thing ( rusty coils) on an X5 with N55, and it was caused by a smart engineers who have designed the " shelf " under the windshield ( and at the rear of the engine bay ). It is made out of three plastic sections if I recall correctly but the main thing is that as it is jointed at the middle... well the water ( rain or ice melting ) comes down right in the center valley directing the water right on the three coils at the back especially.
Now I know that there is a fix that BMW is doing, and they are replacing the middle section ( on recall ) and sealing the joints tight. So there is no more water dripping on the damn coils.
Now reading this tread, I have to go and check out MY own N55 just to make sure I don't have the same crap happening to my coils on my 335i...
Never-ending quest of fixing things that should not brake in the first place...
Gotta to love BMW !

[GB-335xiCoupe]

Originally Posted by myE70

...
Now reading this tread, I have to go and check out MY own N55 just to make sure I don't have the same crap happening to my coils on my 335i...
Never-ending quest of fixing things that should not brake in the first place...
Gotta to love BMW !

Yes, we love them anyway! We love to drive them. We love to work on them. It's a hobby.