Massive Coolant Leak

[ae7456t]

In the spirit of sharing experiences and crowd sourcing ideas, I am looking for thoughts on what I had, today, with my 150,000 mile '06 M35X...

Short trip out to get lunch, and I come to a stop light, when I see/smell a cloud of coolant...Assumed it was coming from the car next to mine, until I saw the temperature gauge climbing...Quickly pulled into parking lot, shut it down, popped the hood, and sure enough, there was coolant everywhere (except in the engine). I took off the engine bay panels and the air intake box to see if I could find the source, but it had dumped out all over the place, so it wasn't clear where it came from.

I had it towed to the shop, and they won't get a chance to look at it until tomorrow, so I am racking my brain on causes of the rapid leak...

1. Water pump/seal - This feels likely, although, I haven't seen many of these engines with such a dramatic pump failure
2. Radiator hose(s) - Possible that the (original) hose(s) failed, but would have expected some warning in the form of a slow leak, first
3. Radiator - Again, possible, but would have expected a slow leak rather than a sudden event
4. Thermostat/seal - Never seen this online, but, again, possible.

I will update when I get the prognosis, but any other potential causes anyone can think of? Similarly, I will have to replace the belts, since they were soaked in coolant, but assuming it is any of 1-4, anything else I should have done while they are in there?

Thanks!

[Ilya]

I'm thinking 2/3. I had a hose failure on a Subaru when I was a teenager happen out of the blue. Got home, pops fabbed his own hose and badaboom, badabing! Back in bidness.

[ae7456t]

OK...If you said radiator, you win (nicely done, Ilya, although, I was hoping for hoses, too).

Not sure how much longer I will keep the car, so asked them to do "the bare minimum" to get it back up and running...Radiator, hose clamps, belts, air filter comes to $808.94, out the door. Radiator alone was $320.

Would love nothing more than to have it towed to my house, and DIY, but not in the cards for this week.

[ae7456t]

One final PS to the "Massive Coolant Leak" experience...When I picked up the car, the shop walked me back to show me the failed radiator...it had about a 2" stress crack across the top plastic tank of the radiator. Best guess is that after 10 years/150,000 miles of expansion/contraction, it had reached the limit.

Good news is that everything appears to be back together and no leaks or other anomalies, so I will take it.

[Ilya]

Glad you got it sorted!