[tahoerdr]

About 3mi into my morning commute, I got an "Engine Hot" yellow warning on the Idrive, then shortly after, it went red and said "Engine Overheat". Gas pedal was cut and I had to drift to the side of the road. The Oil temp was only at 180* on the gauge, totally normal range. I restarted and went a mile to a store, topped off reservoir with 3oz of distilled water to the max line. Same result 1/2 mi later so parked and got a ride into work. The radiator fan runs at 100%.

I changed the serpentine belt this weekend, so I'm worried I might have done something. If the water pump failed, I would think temps would be way high. If the tsat was stuck closed, I'd think the temps would not be moving up exactly at the normal rate. Think this is a bad temperature sensor of some sort? I will be connecting a BavTech tool later today to read codes.

Also, this is a 2008 335xi with 85,000mi so the water pump is getting up there in age.

[cstmx_ryder]

Originally Posted by tahoerdr

About 3mi into my morning commute, I got an "Engine Hot" yellow warning on the Idrive, then shortly after, it went red and said "Engine Overheat". Gas pedal was cut and I had to drift to the side of the road. The water temp was only at 180* on the gauge, totally normal range. I restarted and went a mile to a store, topped off reservoir with 3oz of distilled water to the max line. Same result 1/2 mi later so parked and got a ride into work. The radiator fan runs at 100%.

I changed the serpentine belt this weekend, so I'm worried I might have done something. If the water pump failed, I would think temps would be way high. If the tsat was stuck closed, I'd think the temps would not be moving up exactly at the normal rate. Think this is a bad temperature sensor of some sort? I will be connecting a BavTech tool later today to read codes.

Also, this is a 2008 335xi with 85,000mi so the water pump is getting up there in age.

Water pump....I just had this happen to me a couple weeks or so ago. Ended up replacing the water pump and the tstat for good measures.

Both can be had for $475 shipped from Tischer Online, where I bought mine.

Labor is about 5 hours (for both) for a noob mechanic with some help. Definitely less if you're a competent mechanic that has worked on N54s before, I'd say around 2-3 hours max.

[tc535i]

Originally Posted by tahoerdr

About 3mi into my morning commute, I got an "Engine Hot" yellow warning on the Idrive, then shortly after, it went red and said "Engine Overheat". Gas pedal was cut and I had to drift to the side of the road. The water temp was only at 180* on the gauge, totally normal range. I restarted and went a mile to a store, topped off reservoir with 3oz of distilled water to the max line. Same result 1/2 mi later so parked and got a ride into work. The radiator fan runs at 100%.

ummm... I'm pretty sure that's an "oil temp" gauge below a 335's tach, not "water temp"

[JamesM3M5]

Yes that's oil temp not water. Kinda dumb that there's no coolant gauge or dipstick.

Water pump is dead. Harder to replace on the X drive than a RWD, subgenre are different.

[firemanjust1]

water pump dead your lucky you got 80k plus out of it.

[tahoerdr]

OK thanks for the replies. I ordered the $475 kit from getbmwparts. The local dealer wanted $780 for the pump and tstat.

I'll be scouring the forums for any info on XI water pump DIY info. If none, I'll try to create one. Let me know if anyone finds some helpful install info, it would be much appreciated.

[Gray335i]

same thing happen to me @ 75K .
just replaced water pump and termo this morning.took about 1.5 hrs to get it done.

[cstmx_ryder]

OP,

While you're replacing the tstat and water pump, might as well flush the coolant, since you're going to have to drain it anyway.

This will also be a good time to see if there's any 'fudge' coming out of the coolant tubes when draining. If there's anything brown/black that means your oil filter housing or VCG is leaking.

After the install, don't forget to prime the pump by turning on the ignition (push 'start' button twice WITHOUT holding the brake), and then push the gas peddle all the way down for about 12 seconds or so. You should then hear the pump activating and running through the paces.

If you don't hear the pump turn on and running. Then shut off the car completely and wait a few minutes, and repeat the process above until you hear the pump getting activated. You'll know when it's activated.

The reason why I say this is because when I tried to prime the water pump after my initial install, nothing happened. It wasn't until I tried it the second time that the pump finally turned on and went through its paces.

[tc535i]

Originally Posted by cstmx_ryder

This will also be a good time to see if there's any 'fudge' coming out of the coolant tubes when draining. If there's anything brown/black that means your oil filter housing or VCG is leaking.

cooling is a sealed system, why would oil be getting into it from a valve cover gasket or oil filter housing leak?

[cstmx_ryder]

If you have opened a oil filter housing, then you'd know what I'm talking about....

If I'm not mistaken, coolant and oil run parallel within their own conduits, in the oil filter housing, separated by the infamous 'oil filter housing gasket'. When that gasket is deteriorated or leaking, coolant WILL get mixed with the oil.

That's how and where the magic happens....

[tc535i]

good to know, I wasn't aware they were separated by just a gasket there

will keep that in mind if I ever see signs of chocolate milkshake