I'm not doubting my car's reliability, but this coolant leak just showed up at some inconvenient time for me.

I drove the car on sat and I saw a huge white cloud of smoke behind me, so I pulled over as I thought to myself "oh , the rad just blew", the temp didn't spike as I stop'd the car as soon I spot'd the smoke.

Tow the car back home, got on the phone with the dealership, they say they don't know if they'll fix the problem for free until they see the car. And the dealership is about 70km away, so that's a damn far tow. Philip (Ajax5678) dropped today after work to check out what's wrong.

we see stream of coolant shooting out right about underneath the tranny or the firewall, we can't see which pipe is coming out from, but we are pretty certain it has to do with heater/ac stuff.

so before I get the car to Philip's work place, what other common stuff could cause coolant leak on a E39 540??

When mine 'went' it was from the waterpump, just decided to destroy itself (guess they're famous for that). I imagine sooner or later my radiator and expansion tank will soon follow. As far as under the car near the tranny I can't help you there. I don't have a bentley yet.

hey, quick q, how did you know it was from the water pump??

after careful look and shooting ideas, we've came up the following guess:

from www.540i6.com/probsfixes.html it talked about possible heater line, we didn't jack the car up for careful check, going to get the car into a shop and examine it more carefully.

anyways, we think that the bad passenger's side engine mount has caused the engine moved quite a bit, and possibly torn the coolant line. Because it drips periodically, like it'll drip, stop for 5min, drip... stop... drip.

what happen to the E39 FAQs?

I believe the heater core return or send lines may be the culprit if you say the leak is coming right around the firewall. I've had a hose burst there in an older car - but I'm surprised that it happened in such a new car (relatively).

Should be pretty easy to find the leak though - just jack it up and put some coolant in there are get it up to operating temp - pretty soon crap will start spewing out.

I had a similar leak a few months back. There is a hose on the right side of the engine bay, left if you are facing the front of the car, behind the actual engine. If you peak past the cabin filters next to the engine you will see an return hose. I believe there are two more hoses in the vicinity of the firewall that could also be causing the problem.

I would bet its one of those 3 hoses that dagoo98 specified. Same thing happend to me. But my dumbass automatically thought it was the radiator, and went and bought/installed a new one. Its a $15 hose, and you could do it yourself if your somewhat mechanically inclined. I am not, and I did it.

going to get it on jacks tonight when I get home.

it sucks that I have to ask my dad to give me rides, I feel like the oldest ride bummers in the world.... sigh.

so you guys think we should write up our own FAQs?

write it up!

bloody hell! I checked it out about 40mins ago when I came home, its not the 3 heater core hoses, then I realized I left my jack & my stands elsewhere, and with the widow-maker jack that's in the trunk, I'm scared to crawl underneath the car and take a closer look.

It looks like its right at the oil pan, I can't see it too clearly since I don't feel like letting the car just crush on my head with those scary jack.

what other coolant pipings that are routed around that area? I'm getting the car towed to my friend's work place tomorrow, I don't have time to deal with this, but I just want to have a basic idea when I get the car there.

update:

I knwo it sounds useless, but hey, if you ever had a coolant leak, you know how hopeless you can feel especially if you don't have a lift, or happen to leave your jack and stands elsewhere.

tow the car to Philip's (Ajax5678) work, so he called me in an hr and told me its one of those heater return hose that goes thru the back of the engine, not the 3-hoses ones, sorry for the bad description.

it basically just drips down the oil pan, so that's a $23 hose.