Grrrit

A few months ago my 545i left me on the side of road. Had it towed to my Indy. My timing case cover gasket(s) had failed along with the alt bracket gasket.

While it was in I had the coolant flushed, oil changed, a couple weathered coolant hoses, new battery, and a clutch kit replaced.

That was right around 3,000 - 4,000miles ago. The car is now sitting at 158,000 miles.

Now to the coolant.
Hi pressure whistle from coolant res (possibly from the rear passenger side cyl head), dripping from the rear of the belly pan, appears dry in the front motor area (except the belly plastic, and steam from water pump area. No more than a week ago (100+/- miles) I had the low coolant level light and I topped off.
During cold nights and throughout winter had steam from front end/radiator that I could see at red lights ( I assumed normal considering weather etc).

I didn't check coolant level after Arrival at home after work at 2:00am (hot motor), was bubbling/boiling back into the expansion tank.

About 300+/- miles ago my passenger side AE bulb failed. I replaced with LED and now it has an intermittent bulb failure, with ZIZA error free bulbs? But after looking for the leak, I noticed the passenger side headlight harness was wet. Possibly the issues are related?

I guess if there's any advice for a good place to start looking I'd appreciate it. I did do some searching and figured I'd ask anyways.

Thanks!

DavidF

cracked expansion tank is most likely suspect. Remove the tank and inspect for cracks.

twh

Changing an incandescent bulb out for an LED bulb isn't as easy as it sounds. The car does a bulb test and the LED bulb doesn't react electrically the same and therefore throws the error. Search teh forum for more info - there are a lot of threads.

DavidF

It is easy to fool the lamp check control system with a simple resistor that emulates the resistance of the filament in a incandescent lamp. Very easy for manufacturers of LED lamps to include the necessary circuitry to ensure the lamp warning is not illuminated.

My right side angel eye lamp is also burned out. I think I will go the LED route as well. One thing the PO should look for is internal headlight wiring insulation failure. Ensure the wires on not shorting out due to missing insulation.

Hyper_545i

+1
I had a similar issue. However the expansion tank appeared fine and crack free. Found it had a hairline crack only visible when under pressure and hot. When cool, I could not detect the crack. Very common on thse cars for the expansion tank to crack / leak with age. Also found the upper radiator hose tha runs along the top of the radiator was cracked. Another common coolant leak area is the coolant temp sensor on the lower hose. The o-ring is known to leak. Some have just replaced the o-ring, I replaced the entire sensor. You want to also check the condition of the other hoses as well with that mileage. Any leaks from the water pump itself?

Grrrit

If I walk around to the headlamp and give it a light tap, it comes back on. But when I catch a bump in the road it ones out haha. I think it might be a wiring issue. I've read that the wire insulation in the hella units fails over time.

Grrrit

The expansion tank didn't appear to be leaking. However I did notice moisture along the frame where the wire harness runs. All in all it was very difficult to tell, we had a severe storm while I was working. Some of the water in the belly pan could've been from that as well.

Grrrit

I'll take a look though, thank you!

Grrrit

Just checked, it appears I have not lost any coolant with it sitting for the past 14hrs. Must only be losing it under pressure during operation. I hope it's just the expansion tank haha

Grrrit

I took a few more looks yesterday. Still no visible leaks on the hoses, rad, or expansion tank. However last night with a flashlight it was really hard to see but it looked like moisture on the block, below the water pump. Which was all very clean after the timing case gaskets and such were done. Tomorrow I'll get the car off the ground and get a better look.