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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 12-29-2012, 09:04 AM
etnav382 etnav382 is offline
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Need some help with overheating

Hey guys, I'm in need of a bit of help. Currently my wife's car is overheating. It used to just overheat if it idled fie a few mins and it also had no heat. It now overheats while driving. The car hasn't been driven in about 2 months, since I just got back from deployment I went to have a look at it. The car started fine and it got up to temp just fine also. I drove it around the block a few times, it still had no heat but was not overheating. Suddenly there was a slight burning smell and the wife said now its gonna start to heat up. Sure enough the needle started creeping over. I took it back and popped the hood and heard some sizzling. After looking around I found the sound of it and have circled it in the pics below.

I've tried searching for these symptoms and found a topic about it while I was out a few months ago but cant find it now. Do you guys have any advice on what I can do/look into to getting this fixed? The only major issue the car is about an hour away from my house at her mom's so troubleshooting might be a tad bit difficult but any help would be greatly appreciated.

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Old 12-29-2012, 09:11 AM
AH673000 AH673000 is offline
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Highly probable it is the thermostat .....
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Old 12-29-2012, 09:17 AM
etnav382 etnav382 is offline
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Ok thanks I'll look into some DIY's on it.

Also, I just re-read my post and I'm not sure if I was clear but there was water bubbling out of the seam where the rubber/plastic meets metal. Not alot but enough to notice when you looked at it.
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Old 12-29-2012, 01:04 PM
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Fudman Fudman is offline
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You don't say what year your car is. But the photo is definitely your thermostat and the symptoms are consistent with a failing thermostat. This is the DIY for a M52 engine:
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Old 12-29-2012, 01:17 PM
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flyboyy flyboyy is offline
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looking at your first picture.. you might as well do the Valve cover gasket too.. it looks liek oil was leaking before.
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Old 12-29-2012, 01:24 PM
etnav382 etnav382 is offline
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Sorry its a 97, and thanks.
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Old 12-30-2012, 11:00 AM
Raulg Raulg is offline
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Mein Auto: 1998 E39
The area circled shows the thermostat housing. It is made of plastic and it may also be brittle. Do you know if it is the original housing?
While in there, I would replace the water pump, thermostat, housing and gasket.
Be careful when purging the air out of the system. There are several good write ups in this forum about it. In my own experience, I had to let the car idle for 10 minutes or so under my watch, and when the temperature gauge started to creep up to the red zone, I turned the engine off, unscrewed the bleeder screw (on the thermostat housing) to let the air out. I lt the engine cool and then re-filled with anti-freeze. I then repeated this process about 3 times until the air was completely out and the temperature would not creep up any more. I test drove it for 20 minutes or so near my home just in case. In my case it was all that was needed.
Good luck with your E39.
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Old 12-30-2012, 02:38 PM
jarhed1964 jarhed1964 is offline
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Yep..... T-stat and housing replacement immediately. Might as well knock out a new water pump while you are at it, check all your hoses, and if you haven't replaced the radiator in the last 7 years, you will very soon. Consider changing the t-stat housing to aluminum. You absolutely can't use that melted one anymore, anyway. Some folks hate the aluminum ones, I've never had an issue with mine since early 2005 when I changed it.

Make sure you bleed it properly. Sounds to me like you have air bubbles in the system from that leak. Bad bleeding will get ya every time.
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Old 12-30-2012, 06:22 PM
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bluebee bluebee is offline
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Mein Auto: 02 BMW 525i M54 auto 130K
I get the horrid smell of burnt 'something' when my car idles - so I think it's the valve cover gasket or the power steering fluid. Probably the VCG since it's closer to hot stuff.

You might have the same problem.

As for the thermostat, tons of information is in this thread:
- What is the temperature of the coolant & when the thermostat opens under normal conditions (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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