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E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

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Old 08-28-2013, 04:56 AM
amebb amebb is offline
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Location: UK
Join Date: Dec 2009
Posts: 21
Mein Auto: BMW 525i
Spark plugs slightly rusty ...?

Hi there

Can anyone help me with this issue that i have found today whilst changing my spark plugs.

The old spark plugs were slightly rusty.... as in the colour was slightly orange almost like rust.

Undernearth they were normal.

I did notice that they were finger tight also....

Is there anythingto worry about ??

I have had NO collant loss etc ... engine behaves and runs smoothly - as normal.

Any help appreciated.

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Old 08-28-2013, 06:14 AM
small_525 small_525 is offline
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Location: Illinois
Join Date: Nov 2012
Posts: 224
Mein Auto: 2003 525i auto
Is the rust on the outside of the engine portion of the plug or the inside portion? If its inside the engine it isn't rust and there are charts/photos online that will give info on what a given look to a plug means. If its rust on the outside I wonder if your driving the car short trips not getting the car hot enough to heat up the parts which could cause condensation and then rust. If its just light rust and the plugs aren't that old just tighten them back down again. Finger tight is just a bit too loose.
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Old 08-28-2013, 10:15 AM
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bluebee bluebee is offline
Seek to understand,^Value
Location: San Jose, California
Join Date: Mar 2008
Posts: 25,236
Mein Auto: 02 BMW 525i M54 auto 130K
Post a picture of your plugs.

Here is an example:
- One user's pictorial DIY for replacing the BMW M54 engine spark plugs (1)
Please read the suggested threads and add value, either by pictures or by descriptions, so the next person stands on your shoulders.
See also: E39 Bestlinks & How to easily find what you need
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Old 08-28-2013, 01:24 PM
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540 M-Sport 540 M-Sport is offline
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Rust is not a good thing, but on the outside is not a huge deal. Do you park your car outside? UK seems pretty rainy, so humidity would cause that if the car is kept outside. Finger tight is a problem. Best to use a torque wrench when installing spark plugs to ensure they are sufficiently tight to not loosen. If you over tighten, they can be a pain to get back out, and risk damaging or stripping threads in the aluminum or "ally-luminum" (as they say in the UK ) valve head.
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Old 08-29-2013, 03:40 AM
amebb amebb is offline
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Location: UK
Join Date: Dec 2009
Posts: 21
Mein Auto: BMW 525i
Hi there

Thank you for your response.

I have cleaned the plugs with a wire brush and then put them back in to the engine.

This time they have been tightened correctly.

yes the car isnt used that much, short trips etc. The average i do in the car in a week is about 40 miles.

The 'rust' is not on the outside of the plug or on its threads but on the electrodes etc.

When i say rust, its not exactly rust as we know it. Its just a redish brown rust colour coating on the electrodes etc that just ribs of when you wipe it with a cloth.

I will keep an eye on the plugs to see if the condition worsens.

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Old 08-29-2013, 03:50 AM
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diggyd357 diggyd357 is offline
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Location: Louisiana
Join Date: Sep 2012
Posts: 637
Mein Auto: 97 528I
Re: Spark plugs slightly rusty ...?

Do you use fuel additives like seafoam or octane boosters, etc... ? Too much will cause the rusty look. Search my posts and you'll find where I had the same problem a while back.... I even posted pics of my extremely rusty looking plugs. I got some really good and detailed explanations on the issue. I don't remember everything off the top of my head, but if you do the search it'll answer your questions.

Sent from my SCH-I535 using BimmerApp mobile app
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