My 01 330ci has been leaking coolant for about a week. I determined it was the bypass hose that connects to the bottom of the coolant expansion tank and runs to the water pipe (BMW part# 11 53 1 436 410). I bought the oem part from the dealership and installed it yesterday. Everything went pretty smooth. I drove the car home from my parents where I work on it, made a few stops. Checked for leaks along the way. Everything seemed fine. The coolant light never came on. When I made it home and got out of the car, I noticed the fan was still running pretty hard. I left again later and the temperature gage shot into the red. Coolant light never came on. When I turned the AC off and slowed down the temp came back down to normal. I stopped the car, looked everything over. After about 10-15 min I started the car. It idled at normal temp. I turned the AC on low and the temp started back up. But this time after turning the AC off the temp didn't drop. I left the car overnight and picked it up this morning. Driving to my parents this morning with AC off, the temp was normal. After I got close to their house, I turned the AC on. The temp didn't go up immediately, but after a few minutes it start to climb steadily.
Any thoughts? I plan to get it up on jacks this evening and go thru what I did yesterday to make sure I put everything back correctly. Any help is appreciated.
Thanks
I would suggest also getting the codes read. It'll give you a good idea of where to start looking. Look at the thermostat as well - these can do bad over time. I've included a link on the procedure below if that's the culprit.
http://www.pelicanparts.com/BMW/tech...Thermostat.htm
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How many miles since you last did a cooling system refresh? Of course, running the AC makes the engine work harder and will exacerbate any cooling problems that you have. After you changed the hose, are you sure that you got all of the air out of the system? Did you turn on the heater to make sure that you got all of the air out?
As for just changing the hose, I'd at least check the rest of the system too. If you aren't aware, the cooling system on E46s is sort of a weak point. You may be having water pump/thermostat issues.
I also suspect air in system. Top off coolant first thing in the morning, on a cold engine.
Perform a proper bleed procedure, you should be good after a couple of cold top-ups.
Is the cooling fan working? Old cars accumulate debre inside their radiator cooling tubes..(calcium, rust particles. This introduces a cardiovascular deficit that in course blocks essential flow and passage of coolant liquids for cool down from the dc 12 volt/ cooling fan.
Last edited by Eaglesail; 06-25-2017 at 02:26 PM.
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