Help Thermostat sticking - BMW Forum

s525icb · 02-29-2012, 03:31 PM

I just bought a 2002 525i, had a few problems but recently in the morning I got in the car drove about a mile and stopped, noticed smoke coming from under the car, open the hood see smoke coming from the back of the motor, and then coolant light and going in the red. The smoke smelled like a burning wire. Not coolant, now I smell coolant and it keeps going in the red then going back to cool within a minute. Reving the engine in neutral does make it stop most times if I am driving, otherwise it stops on it's own after about a minute. Also I can hear a horrible ticking noise that I want to say maybe it's the catalic converer? I am a woman and know a lot about cars but nothing about BMW's. Please help would could be ailing my baby? I also replaced the ambient tempature sensor last week and the idiot that put it on couldn't get it on right and so it's still not working.

Lord Vader · 02-29-2012, 08:52 PM

Sounds like you need to replace your thermostat. Did you check all of your coolant hoses to see of they were cracked or worn and leaking? They can and do come loose and spray coolant. Happened to my car once.

The M50/52 engines were notorious for coolant system problems. They had several plastic components that were made with plastic that became brittle and failed. Including thermostat housing and coolant expansion tank. If the cooling system is original it's a good idea to replace it. It usually runs around $500 for upgraded aftermarket aluminum components. And can be replaced in a weekend if your DIY capable. The peace of mind knowing yor coolant system will now last the life of the vehicle as opposed to the average of 100,000km is well worth it.

s525icb · 03-01-2012, 10:10 PM

Blown head gasket! Only had the car two weeks. I don't know what to do now, no smoke coming out of the tail pipe but the noise is horrible! It also won't get up and shift into gear and the whole motor shakes. I am sooooo upset! Has anyone ever used that sealant stuff? Does it work. I got a lemon. I'm sure this problem was there before I've had nothing but problems since I bought the car. I love the car and I'm so sad.

70marlin · 03-02-2012, 06:51 PM

Time visit your friendly mechanic. Sorry :<(

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Lord Vader · 03-02-2012, 10:41 PM

OP, the car isn't nessecarilly a lemon. The M50/52 motor is prone to overheating and can blow a head gasket quite easily. The motor may still be fine. If your DIY capable and you can fix it in a weekend. The cost of the job is all labour. A headgasket is around $100 but the job can take 6-8 hours to complete. I don't recommend any sealant stuff. If your gonna fix it save yourself the trouble and fix it once. Sealant may not work and be more costly in the end.