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Discussion Starter · #1 ·
I have a 2006 325CI and just replaced the battery. Now i am getting an intermittent low coolant warning. Could this be related to changing the battery or something else? Coolant level is normal with no leaks and engine temp normal as well
 

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Changing the battery shouldn't have anything to do with your low coolant warning. Check you reservoir coolant level. There should be a plastic rod under tge cap that shows you tge coolant level. I believe it's supposed to come to top to indicate full. If this is ok, you may have a bad coolant level switch.
It's just coincidence this warning came up after tge battery change.
 

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Thanks rav31. That switch is apparently at the bottom of the reservoir.
Well, it installs from the bottom of the reservoir. Depending on how old the reservoir is, you should just replace it all. These are a known weak point. Reservoir usually cracks & will allow another coolant leak issue. Been there on just about every Bimmer I have ever had.

 

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Thanks rav31. That switch is apparently at the bottom of the reservoir.
It's a sensor attached to the bottom of the Expansion Tank. If it were to come loose and just dangle below the ET, the coolant light would be on all the time. It's a magnetic sensor in that a floating magnet inside the ET activates the sensor when your coolant level is low.
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thanks probably time for the overhaul. But how much to do? One guy suggests a "tune up"
Exp. tank, water pump, upper and lower hoses , Thermostat. Car has 70K miles
You need to find where the leak is first. At only 70k miles, none of the components should need to be replaced so a complete overhaul would, IMHO, be unnecessary. It could be a simple as replacing the ET Cap.
 

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All2Kool
Thanks again for the advice. Just drove it and it looks like the radiator cap is sealing properly
I don't know about that....it's still a 16 year old car & the cooling system is a know weak spot. I have an '05 & replaced mine at 75k along with pulleys & belt. I guess you can wait until it strands you or worse, cook the engine.
 

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All2Kool
Thanks again for the advice. Just drove it and it looks like the radiator cap is sealing properly
After your next drive, open the hood, take a flashlight and shine it down at the Splash Guard just beneath the ET to check for dripping. The rubber O-Rings on the bottom of ET can fail in time.
 

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SOME evaporative loss is to be expected; if you have to top off the system once a year that’s fine. Now that you topped it off (hopefully NOT raising the float stick to the second bubble), monitor the level weekly.

That said, the cooling systems on any BMW made in at least the last 20 years is a major week point. Prudent maintenance has you replacing every hose, the thermostat, and water pump every 100k miles. I also run a 1.2bar cap instead of the stock 2.0. I also like the billet Al water pump pulley upgrade over the stock plastic unit, along with GAS DISA upgrade.

Yes, modern cars still require tube ups. Fluids, spark plugs, chassis grounds, etc. Gapping points and setting air gap on VRs has been replaced by other tasks (like gutting and replacing the cooling system).


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Thanks for the reply. I just took a drive and coolant down to top of indicator but the flat area that covers the air intake was wet. So could be faulty radiator cap
More likely only if overfilled. I’ve ran mine with a purposefully loose cap to limit pressure when I had to get it home with a cracked expansion tank; the crack didn’t open until 18psi.

Hose off with fresh water and drive again. If the system was overfilled it will vent through the cap.


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Discussion Starter · #19 ·
As a follow up, After driving my car for about 10 miles i only added about 2 oz. of distl. water/coolant. Temp was steady while driving. However my mechanic is about 30 min away. So i wonder if it safe to drive that far. As a further follow up i have no static leaks at all as coolant level is same over night
 
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