Hello, I'm new to the forms so bare with me. I have a 2001 BMW 330i I recently purchased. It has around 146k miles, and the service engine soon light came on. I took it in to a BMW mechanic (not the dealer, but great mechanic that only deals with BMW's) and told me my thermostat was stuck open. The light will sometimes go off and stay off for long periods of time and will sometimes stay on. Car does seem to have lost some of its good acceleration and torque, so clearly there's something wrong I just don't know if the thermostat would make that much of a difference in acceleration? Also, is it bad to drive with it stuck open? I have the part to change it just to lazy to do it myself and too cheap to pay the mechanic to do it. How urgent is it? Could it possibly be something else? The light will sometimes go off and on, and I noticed the oil light will come on for a few moments when I start the car up, and will go away. I don't know why it does because I recently changed the oil and it has the right amount it, and I even reset it on the dash so the next inspection isn't until a certain amount of miles. Any suggestions on what it could be or what to do? Quick little side note too, is the car faster in S mode from 0-60 or faster with M1-M2-M3 manual gear shifts? Thanks
Modern engines are designed to run in a specific temperature range. Your engine is an M54. It’s a great engine. The optimal temperature range for the engine is 95* to 100*C. Operating in a lower temperature range decreases engine performance and efficiency. Google “BMW E46 hidden OBC functions.” Test #7 will show you the temperature of the engine as seen by the engine computer (DME). Install a Whaler thermostat. Do not ever install aftermarket cooling system parts. NEVER! Go to fcpeuro and buy parts made by the suppliers to BMW. These we are called OE or OEM parts.
Hello and welcome to the forum! In case you do need a new thermostat, take a look at the link below. Please let us know if you have any questions and we'll be happy to assist.
http://www.pelicanparts.com/catalog/..._pg2.htm#item4
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Only use genuine bmw or their manufacturers parts. Since your thermostat is bad and 146k miles you will probably need to replace some or all of the coolant system. Check your hoses and radiator as well.
Motorad is an aftermarket brand at least in the world of BMW. OE for E46's is Wahler which is now owned by Borg Warner. Mahle/Behr thermostats are also an acceptable replacement for this vehicle. Like mentioned above these electronic thermostats are finicky and it's easier tos tiock with the OE/OEM equivalent than gamble on something aftermarket. Just our $.02.
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correct on the thermostat causing engine to have poor performance. some BMW e46 suffered from a problem where the t-stat electrical connector would leech coolant up the insulation of the wiring and get to the dme. when replacing the thermostat inspect the connector and wiring also a visual will indicate that coolant has been in the connector. I also agree on the stock BMW thermostat or OE replacement. I have run aftermarket on my e46s and have had good luck others not. I also keep a good eye on things. I would replace the water pump also its a belt removal and 8 extra 10mm nuts to remove. then replace the water pump pulley with a new or metal one. I have seen them crumble apart and cause belt to wrap around everything.
have fun and enjoy the car. they are not hard to work on and can be serviced by the DIYer quite easily.
Level 1 Certified BMW tech.
So I replaced the thermostat with the Motorad considering I already had the part. I did not bleed the antifreeze because little came out when I took off the hoses. I regret both of these, shortly after testing it the temperature was fluctuating and I started to smell antifreeze. I quickly turned off the car and noticed a hose had came off and spewed antifreeze everywhere. I put the hose back on and secured it and bled the coolant. After I tested it again I noticed antifreeze leaking from the bottom. I took out the Motorad and am just going to return it. I purchased a Wahler from FCPEuro and am going to switch it in. Is it possible I put a crack in the engine head or broke the reservoir? The leak is on the bottom, not coming from the thermostat.
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