E 39 Expansion tank blow up

[Ahmed Fatairy]

HI ,

while i was driving the temp gauge moved to red then coolant temp sign turned on i push the gas twice then i heard a big bang it was the tank exploded and i turned off the engine , the crack was from the upper side and i was in no parking area which means i have to drive it so i put some water after some time when it cools down a little till the crack i drove it like 3 KM then the pointer goes to red again i pull over and wait then i fill it again , then i drove 3 more km and the pointer was in red , then the oil presser sign turned on and i stopped and turn it off , waited for about 10 min no water and no water access as well then start it again and the oil lamp was off i drove it to parking for about 500 meter and stopped and the oil sign turned on just before i stopped the engine again , during the last 500 meter drive the engine sound was weird .

so why the tank was exploded in the first place and just after the pointer goes to red.

thanks
Ahmed

[bigjae1976]

The tank is not your only issue. You probably were overheating, stopped, built up pressure in the coolant system which then blew up your expansion tank.


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[Ahmed Fatairy]

overheating why????

[bigjae1976]

No idea. If I had to make a wild guess, I would think it is either the water pump or fan failure.


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[Ahmed Fatairy]

or maybe the thermostat ???

[bigjae1976]

or maybe the thermostat ???

Thermostats fail open. Probably not.


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[Ahmed Fatairy]

well we will know soon enough tomorrow , its Sunday here

[bmwdirtracer]

I'm sorry, but it's my guess that you're now going to need a new engine. "No Parking Zone" or not, you MUST NOT drive a BMW when the temp needle is at the red, or when there's no coolant in it. And the fact that you saw the oil pressure light, too??? Not good at all.

Here's a link to an E39 which did, essentially the same thing you did:

https://www.bimmerforums.com/forum/s...from-home-quot

[Ahmed Fatairy]

well i will post tomorrow when i go to the mechanic

[MIKYZZ4]

Be ready for the worst, unfortunately.

[bigjae1976]

You can find a good used M5X engine for well under $1k. Not the end of the world.


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[Irish M5]

Probably not in Egypt.


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[ross1]

This could be from a failed head gasket allowing combustion gas(and pressure) into the cooling system. If it has been failing you were likely consuming coolant which would lead to the overheating, etc.
Probably bad news for that engine as when badly cooked they pull the threads for the head bolts clean out of the block. BMW's official position on that is to replace the block. They can be successfully repaired with "Timesert" thread repairs but it is costly to do so. Chances are very good, near certain, the cylinder head will also need machining.
Having seen the oil pressure warning there will probably be some damage the crankshaft bearings too.
Best to cut bait and find a replacement engine if you can as repairing the existing will be quite labor intensive.
Too bad you are half a world away, I have two of these engines collecting dust.