[shadowx360]

Hi, yesterday I was drove about 60 miles on the highway going at around 100 mph (~3400 RPM) when all of a sudden, the engine temperature warning light turned yellow and then within a few seconds, turned red. I had to drive for about a mile more before I had a free median to park. When I opened the hood, the engine compartment was pretty hot and I found coolant sprayed all over the place. A quick check on the roof of the hood showed that the coolant expansion tank's cap had released a lot of coolant on the side. The engine was running fine though, I checked the belt and water pump and both were fine.

I left the car on idle for about 5 minutes (fan was in highest setting and I figure an idling engine with a maximum speed fan cools faster) and then I shut it down for about 5 minutes. On startup, the temperature warning was gone so I started driving. A minute later, the Low Coolant light comes on, and I had to pull into a gas station to wait for the engine to cool enough to add more coolant. The car ran normal after that, and I drove it for about 40 miles since then, mostly highway.

Quick background info: 2006 330i, ~57k miles, been on many ~100 mile highway runs at high speeds, never had a warning light come on before

My question is, does anyone know what could cause this issue? I am not sure if a bad cap caused a depressurization that drew liquid out of the radiator, leading to the quick overheat (a 3 second jump from no warning light to yellow overheat light to red overheat light seems too quick) or if the engine did overheated and the warning system was too slow to respond, and the cap released the gases because the engine was overheating so much that the liquid turned into gas.

[e90pilot]

Most likely, your water pump is on its way out. Check for codes stored in your ECU. I'm willing to bet you have some water pump errors stored. Your water pump is electric and appears you still have the original one. There have been several revisions since. You're also at a mileage where it's common for '06 model years to have this problem. There's another thread in the Maintenance section that has several well documented cases.

[shadowx360]

Ok, thanks. I ordered a cable that can be used with INPA, a K+DCAN cable. Can I use that to check for codes? Also, a new water pump is around $600, is there a trusted source for these parts except through dealership?

[aandrew335]

same thing happened to me on saturday. made a right turn and accelerated, felt a lag, then got the overheat warning. car went into limp mode. opened the hood and coolant everywhere. had to get it towed to BMW and got the water pump replaced under CPO warranty. Car is an 08.

[GermanAutoAuction]

see if the thermostat is faulty, could just be a simple fix. water pump is very noticeable if going out. could be just something very minor

[Efthreeoh]

It's the water pump; no if ands or buts. Replace it.

[shadowx360]

Hm, like I said, the lights went away and the car has been driving fine since that incident. I won't have the time to replace the water pump for a few weeks, do you guys think I can drive on this? Most of you have said that you got it towed and then serviced, anyone managed to get more time out of that? I only drive it about 2 miles a day.

[Efthreeoh]

Originally Posted by shadowx360

Hm, like I said, the lights went away and the car has been driving fine since that incident. I won't have the time to replace the water pump for a few weeks, do you guys think I can drive on this? Most of you have said that you got it towed and then serviced, anyone managed to get more time out of that? I only drive it about 2 miles a day.

The water pumps fail becuase the control electronics fail due to over heating. Once the car cools down the pump may work again for a while. Check for low pump speed shadow codes to check for the pump going bad.

[Yvette]

ok, I am having the same issue today.

[bennettdavis]

I am having this same issue. drove for about 15 minutes, engine overheat warning came on and then a minute later engine shut down with warning message of overheat. Water temp is normal, fluids are full, no leaking hoses. is this the thermostat or water pump? if its the water pump is this something I can change?

2007 335i

[e90pilot]

Originally Posted by bennettdavis

I am having this same issue. drove for about 15 minutes, engine overheat warning came on and then a minute later engine shut down with warning message of overheat. Water temp is normal, fluids are full, no leaking hoses. is this the thermostat or water pump? if its the water pump is this something I can change?

2007 335i

Are you sure your water temp is normal? The overheat message comes on when the water temp is too high. That gauge on your cluster is oil temp. Scan you car for stored errors. Water pump and thermostat errors won't trigger a warning light.