335i 2007 limp mode coolant light help

uncle don · 12-31-2019, 11:20 AM

wanted to make sure what was going on before I threw parts at it...
few days ago I got a low coolant light and so I topped it off with maybe 1/2 gallon of bmw compatible coolant and drove on.
Three days later driving to work yellow coolant light comes on dash...then seconds later it turns red and limp mode occurs and I cruise into a gas station close by.
temp gauge still read fine, car didn't seem crazy hot under hood...etc...
got it home, tried the test to turn pump on and it would not turn on...could not hear anything. also I had no heat, vents only blew cold air on way home... so assuming no coolant is circulating, pump not coming on...am I 100% need a water pump? or am I missing something?
also while im at it if it is water pump...what else should I do or bolt on while in this tight space? its bone stock....original car with 119k miles on it.
thanks in advance for advice....and direction or anything else to try?

edit: I will add that the coolant was pushing out of the reservoir up top, reason I had to add a little the first time...so thru this only coolant leak I have had is pushing it out the top.

tcphoto · 12-31-2019, 05:10 PM

To begin with you need to add equal parts coolant to distilled water. A 1/2 gallon is a lot of coolant so I think that you shouldn't drive it till you figure out if it's just the ET lid, water pump or a hose. It is recommended to replace the thermostat if you replace the water pump. At that mileage, I would do a coolant flush while you're there also.

uncle don · 01-02-2020, 03:01 PM

about 30k miles ago it had radiator hoses and a flush done.
I have it at a second mechanic today and he said there still trying to figure it out....and said the battery was pretty weak and asked if I had any issues with it. battery went completely dead just trying to run a scanner on it. so I have heard that low voltage will cause a lot of problems on these cars, sensors, water pumps acting strange etc... only thing is it has cranked over kinda hard in colder weather here like it may be getting old....but I have NEVER had a light on or a warning that my voltage was low or battery bad??? should If this is the case?

nyteryda3 · 01-08-2020, 06:05 PM

could it just be the expansion tank? when you filled, did you visually see any coolant leaking? might just be one of those crappy hoses, if not then expansion tank, if not then water pump+thermostat.

uncle don · 01-14-2020, 08:32 AM

water pump was bad. also replaced battery.
all is well.

12-31-2019, 11:20 AM	#1
uncle don Private 2 Rep 50 Posts Drives: 2007 335i E90 auto Join Date: Jan 2016 Location: elizabethtown, ky iTrader: (0)	335i 2007 limp mode coolant light help wanted to make sure what was going on before I threw parts at it... few days ago I got a low coolant light and so I topped it off with maybe 1/2 gallon of bmw compatible coolant and drove on. Three days later driving to work yellow coolant light comes on dash...then seconds later it turns red and limp mode occurs and I cruise into a gas station close by. temp gauge still read fine, car didn't seem crazy hot under hood...etc... got it home, tried the test to turn pump on and it would not turn on...could not hear anything. also I had no heat, vents only blew cold air on way home... so assuming no coolant is circulating, pump not coming on...am I 100% need a water pump? or am I missing something? also while im at it if it is water pump...what else should I do or bolt on while in this tight space? its bone stock....original car with 119k miles on it. thanks in advance for advice....and direction or anything else to try? edit: I will add that the coolant was pushing out of the reservoir up top, reason I had to add a little the first time...so thru this only coolant leak I have had is pushing it out the top. Last edited by uncle don; 12-31-2019 at 11:26 AM..
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12-31-2019, 05:10 PM	#2
tcphoto Brigadier General 3525 Rep 3,043 Posts Drives: E92 335i 6MT Coupe Join Date: Dec 2009 Location: Nashville, TN iTrader: (1)	To begin with you need to add equal parts coolant to distilled water. A 1/2 gallon is a lot of coolant so I think that you shouldn't drive it till you figure out if it's just the ET lid, water pump or a hose. It is recommended to replace the thermostat if you replace the water pump. At that mileage, I would do a coolant flush while you're there also. __________________
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01-02-2020, 03:01 PM	#3
uncle don Private 2 Rep 50 Posts Drives: 2007 335i E90 auto Join Date: Jan 2016 Location: elizabethtown, ky iTrader: (0)	about 30k miles ago it had radiator hoses and a flush done. I have it at a second mechanic today and he said there still trying to figure it out....and said the battery was pretty weak and asked if I had any issues with it. battery went completely dead just trying to run a scanner on it. so I have heard that low voltage will cause a lot of problems on these cars, sensors, water pumps acting strange etc... only thing is it has cranked over kinda hard in colder weather here like it may be getting old....but I have NEVER had a light on or a warning that my voltage was low or battery bad??? should If this is the case?
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01-08-2020, 06:05 PM	#4
nyteryda3 Enlisted Member 28 Rep 40 Posts Drives: 2011 BMW 328i - LCI Join Date: Jul 2012 Location: SoCal iTrader: (0)	could it just be the expansion tank? when you filled, did you visually see any coolant leaking? might just be one of those crappy hoses, if not then expansion tank, if not then water pump+thermostat.
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01-14-2020, 08:32 AM	#5
uncle don Private 2 Rep 50 Posts Drives: 2007 335i E90 auto Join Date: Jan 2016 Location: elizabethtown, ky iTrader: (0)	water pump was bad. also replaced battery. all is well.
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