Oil Filter Housing Leak Fixed then Coolant Expansion Tank Burst
 

Long story short, I took my 2011 X5 35i in to an independent shop to get an oil filter housing gasket leak fixed. Within about 50 miles of driving after that the coolant expansion tank burst while I was sitting in traffic.

Is it possible that the oil leak repair caused there to be air in the system which caused the tank to burst?


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No. Air in the system would not cause the tank to burst, as the tank is designed to vent excess pressure in an overheating or high temp event.

My tank broke while sitting in my driveway updating my navigation. It just started steaming.

The tank is plastic, and gets weak from constant heat cycles inside and out. Think about it. Hot, cold, hot, cold, hot, cold every time you start and stop the engine. The harder the plastic, the more brittle it is, but the softer, the more easy it would melt.

It's one of those things that just happens.

Kind of. The expansion tanks fail because the plastic gets brittle with time and they then crack. During the repair they had to remove the hose on the bottom of it to gain clearance. They are on there fairly tight and removing and replacing may have accelerated the failure, but only because it was close to failing anyway.

Just my opinion though.

Agree.

Its a pretty simply replacement... are they charging you $$$ for this? If they made good money on the initial repair, they might be willing to do it for parts cost alone. (They will still make enough to pay the mechanic out of the part mark up....)

Unfortunately I was on my way to the airport for a week long work trip and just wanted it to be fixed when I got back so I had it towed to a different shop that was closer. Didn’t think about the 2 possibly being connected at the time.


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The expansion tank and connecting pipe has been one of the Achilles heel of the E53 and E70 models. You would think BMW would have figured out how to use a plastic that is more durable.

Recently, my oil filter housing leaked and dripped on the idler pulley causing chatter. One new serpentine belt and a factory oil filter kit later and i was back on the road. My mechanic said other than factory filter o rings sometimes fail. Mine was an after market and it did fail.