Small to Huge Coolant Leak

I Had a little coolant leak before I had to make a hour drive (at mostly 70mph). The long drive went well the first :30 or :40 then blew out the leak and overheated like crazy. It took almost 10 miles before I could get an off ramp. By the time I could get off the highway and open the hood plumes of smoke were pouring out. I found a rancher across the street to keep my car til I could find a tow truck open on Monday (today).
Do I need to replace the radiator and the hoses or just the hoses? I had a hard time finding where the leak was came from. What else may have been harmed?
Radiator and hose replacement doesn’t seem very hard after video reviews. I’d like to fix it myself if possible.
Honestly I want to fix it back up and sell it. I’m in over my head with these expensive BMW fixes.

Rent a pressure tester from Autozone (or whichever parts store is closest to you). Fill the radiator with water, hook up pressure tester and see where it’s leaking from (if you don’t figure it out while it’s filling up). Then you’ll know if the problem is with the radiator, hoses, water pump, thermostat, water outlet, etc.

I worry that you may have damaged the head gasket if you drove that long while it was overheating, especially if it was smoking that much once you finally stopped. Next time, just pull over into the shoulder and shut the vehicle off.

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Most likely


+1. You were probably fine until you kept running it after it overheated. You didn’t say what year/model of BMW this is, but BMWs in general are expensive to fix and need fixing more frequently than many other vehicles. I agree with your inclination to dump it as soon as you can, but if you’ve damaged the head gasket(s) (and potentially warped the head(s), you’re not going to get what you want for it.

For future reference, any coolant leak no matter how small needs to be treated as a “fix it before you drive it again” situation, precisely because of what happened to you.


This bears repeating:

Additionally, a head gasket breach and cylinder head warping might not be the only internal damage that took place as a result of continuing to drive while the engine was overheating. It is very possible that the cylinder walls have been “scored”, and that situation–in addition to head gasket/cylinder head/ and possible radiator problems–would mean that the repair costs will be very high.

Depending on the age, odometer mileage, and overall condition of the vehicle, it might not be cost-effective to repair it.


Along with the engine, the transmission was probably destroyed too.


I agree with the others. Be prepared for expensive (and unnecessary) collateral damage here.


You get expensive repairs by ignoring little ones, Just magnified when it is a BMW. Someone who sees nothing wrong with driving around with a coolant leak should not own a European Luxury xar.


Just went from a small to huge repair bill.

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