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Discussion Starter · #1 ·
Hi guys,

I did search but couldn't find right answer, maybe I'm not good in searching. :D

Anyway, I have 323 auto trans.
when I start my in the morning, it takes a less than 1 mile to warm up(temp needle goes middle).
However, from 2 weeks ago, warm up take a lot slower, like I need to drive 5 miles(city drive with lots of light), then it reach middle which usually takes one mile to reach.

What do you guys think?
Thermostat? Right?
I don't have over heating, leaking nor lower coolant.

Hum,..I want to fix it before get worse.
Anyway, thank you guys.
 

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I'd say the 5 minute warm up is more normal. The thermostat is opened by a heating element controlled by the ECU that allows the cooling loop to be opened earlier. The result is slower warm up. Maybe air temps have been higher recently.
 

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Discussion Starter · #3 ·
Hm, 5 miles like 12 minutes.

I could tell it has been a lot slower than before. It usually takes 5 minutes or 1 miles to drive.

Oh, one more thing, I start car and hit highway right away, I drove over 10 miles(80m/h) and was still 1/4 temp gauge. when I exit and wait for signal, it reach at middle.( it was last weekend )
 

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Those are the exact symptoms of a stuck-open thermostat. When you drive fast, air cools down the coolant and that's why the needle does not go to the right until you stop.

Although there is no immediate danger in driving with a stuck-open t-stat ( I drove for weeks without reallizing the same problems with mine), your t-stat is mal-functioning. It should be replaced soon.

You will see a big improvement in mileage once the t-stat is replaced because your car will operate with the correct engine temperature and emission settings.
 

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2016 340i xD 6-spd
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+1 classic stuck open therm.

Look into the cooling overhaul, OP, while you've opened up part of the system anyway, might want to broaden what you do...especially if you need to anyway!

Like nice time for at least new belts! Might need a whole flush anyway...something by way of an ET, WP, perhaps a nice tensioner? Just saying. definitely therm...but possible opportunity for more excitement in the same neighborhood.
 

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Discussion Starter · #6 · (Edited)
Thank you guys. =)

Hm, another DIY this weekend, haha.

By the way, there is a small thermostat in expansion tank. What does it do?
Do I need to replace it too?
 
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