Why did my car explode?

[SilentKIL]

q

[613EDRTY]

holly shit! Expansion tank cap is suppose to let the pressure out isn't it?

[zig553]

Is there a blockage in the radiator somewhere and the pressure caused it to burst? That is really weird. Never seen that before.

[SilentKIL]

New radiator, hoses, everything. I would hope not. Although it did sit from January til now without being run...

[ELVA164]

Seeing the pictures, I still think it's a bad head gasket.

[CorvallisBMW]

Clearly the expansion tank cap failed to lift and the next weakest point in the system was the tank itself (surprisingly). But the pressure should never get high enough to lift the cap in the first place, unless something is wrong. Without more info though it's hard to know.

[101]

I'm not convinced this was just pressure alone. That tank also shows some signs of melting.

Since just about everything else in the cooling system is rubber or metal (the radiator side tanks are made of a more durable plastic), the tank would the weakest point when it comes to dealing with high temperatures and pressures. And the bottom of the tank is ground zero since the coolant is contacting it there and the exhaust manifold is nearby.

Could your IS engine have overheated due to a bad mechanical fan clutch and/or non-working electric fan ... causing both high pressure AND temperature of the coolant and combined with a bad pressure cap caused the catastrophic failure of the expansion tank?

If so, you may have a head gasket job on your IS in your future. Check the compression and see if there is any mixing of oil and coolant in the engine. You may have gotten lucky.

[ST1G]

I'm not convinced this was just pressure alone. That tank also shows some signs of melting.

Yeah, I agree. Head gasket letting super heated gas into the coolant, heating the water causing a great deal of pressure and heat, eventually bursting and melting the plastic of the expansion tank.

[efficient]

Not to jack this thread but I've noticed my car when it's been driven and its hot. my hoses will expand and I've noticed that I have coolant seepage coming out of some hoses.i already tightened the clamps.

Any suggestions?

[ST1G]

Not to jack this thread but I've noticed my car when it's been driven and its hot. my hoses will expand and I've noticed that I have coolant seepage coming out of some hoses.i already tightened the clamps.

Any suggestions?

How old are the hoses? Probably time for replacements.

[efficient]

How old are the hoses? Probably time for replacements.

2 years now, non oem hoses.

[ST1G]

2 years now, non oem hoses.

Yeah, hoses should get firm, but normally you shouldn't see them "bulge" I would find some OEM quality hoses.

[Old city bimmer]

Looks like your expansion tank was misting coolant out and your ignition wires arced at it. I'm sure there was grease or some kind of chemical there also on the tank to cause that much of an explosion. Glad you didn't have a engine fire.

[ELVA164]

Interesting theories in here. I think the plastic just looks stretched, not melted.

[mucoyekul87ETA]

Interesting theories in here. I think the plastic just looks stretched, not melted.

Total bummer, but an interesting event nonetheless. I have never seen this before. I like St1g's theory the best, as it explains the heat/pressure build up best, but I also agree that the expansion tank does not look melted, it looks stretched.