radiator expansion tank exploded

I have a 96 e230 and the expansion tank on top of the radiator exploded causing damage to the bonnet of the car. I was stuck in traffic and noticed
that the temp was running a high (just below the red ). I was hoping to pull off but it went before I had a chance.
Has anyone had this problem or any idea why the expansion tank would blow in half. I'm more annoyed about the damage to the bonnet as it looks like I will have to get a replacement.
Alan
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Jammed radiator cap could cause cooling system to build up pressure. The cap acts as relieve valve. Did you do any repairs to your cooling system before this incident?
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Hmmm, If the other guys radiator cap theory is wrong, then I am afraid you may have some head gasket issue?
Perhaps the head gasket is leaking in such a way the blowby if super heating and pressurizing the coolant?
Sorry for the negative thinking, but it seems like a possibility?
Marty
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I've seen this a few times. Mainly on the C class which uses the same radiator configuration. MB UK have passed on some information. Apparently it's something to do with a pocket of super heated water that expands rapidly when it reaches the expansion tank. Thus causing the top of the rad to explode. The coolant level is a contributory factor. If it's too low, it leaves more room in the rad for steam pockets to form.
said:

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thanks Lee .. this is very intresting as I checked the coolant level every week and it was ok.
said:

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Sounds like some sort of super-heated air/vapor bubble being passed through the system. Strange.
My follow-up question would be this ... Has your vehicle had latelya cooling system flush? If so, that could account for the issue.
It migh also be a design flaw. (Sorry 'bout that conclusion) But it's just not something that happens to other vehicles. Does this happen to all C/E or just a certain series? If so, which? Has there been a related recall (whether govt. or voluntary)?
Collin KC8TKA E320/97/now I'm scared. :(
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quite a common prob have been know to damage the bonnet when they let go new radiators have been modified i have been told so looks like it was a design fault

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