01-26-2024, 05:47 PM | #1 |
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Engine coolant is boiling
Took my 2015 335i (n55/f30) to an Indy BMW shop to get battery replaced. Tech pulls me back and shows me my coolant tank under the hood is steaming (he removed cap). Said it was boiling when I first pulled in. I later confirmed, after some light driving, that yes when I open the cap, it starts to boil violently.
Tech told me it was probably mostly water, someone (bmw dealership is only other tech whose touched this) must have been topping it off w water. He suggested a coolant flush and refill. Is this a big deal that needs to be addressed asap? I’ve probably been driving it like this for 1.5 years. I’ve never gotten a low coolant or high engine temp warning - so is this nbd or is this a pretty urgent problem? |
01-26-2024, 05:58 PM | #2 |
Charles B
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Yes you need to address this ASAP. The whole process is not a big deal and it's not a ton of money. I would have the indy shop do it if you're not comfortable doing it yourself.
I wouldn't drive it until this is taken care of. |
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GrabEmByTheBimmer16.00 |
01-26-2024, 09:32 PM | #3 |
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Never open the cap when it's hot. The reason it appeared to boil is that it's under pressure, which raises the boiling point. When you took the cap off you removed the pressure. A mechanic should know better. I wouldn't be surprised to find out he's a shyster who pulled the cap on purpose to make it look like something was wrong to drum up some more business. Google how to open the hidden menu so you can see the coolant temperature. It should run between 195 and 220 degrees.
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01-27-2024, 02:00 AM | #4 | |
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01-27-2024, 09:05 AM | #5 |
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If there's too much coolant the car will purge the excess by itself. Water boils at 212 degrees when there's no pressure, but under the usual 15 PSI pressure in a radiator it goes up to 257. If it's a 50/50 mix it's 268. That's why it went nuts when the cap was pulled. The lack of an engine temp warning is also suspect. Open the hidden menu, watch the coolant temperature just in case.
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01-27-2024, 04:42 PM | #6 | |
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I’m guessing this is not ideal? Now I’m wondering if a top up of coolant is all that’s needed, or if I really do need a flush as the shop suggested. |
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01-27-2024, 06:30 PM | #7 | |
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01-30-2024, 11:49 AM | #9 | |
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