Expansion tank - huge crack

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Lewischarlie_95

Member
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So I have 2008 e86 z4 3.0 si and out of nowhere my expansion tank exploded with a huge crack. (See image).

I’ve refitted a new tank, bled the system and filled with new coolant. I’ve ran the engine and there is a vague whiteness to the smoke out the exhaust.

Has something major happened to cause this failure in the tank or do you think it is just an old part that eventually cracked.

Any help would be appreciated.
 
Wow. Catastrophic failure!
Can't be 100% but it looks like it's failed along a mould-seam (?)
 
Well the expansion tank is a very well known failure point on these cars, but it's usually hairline! makes me wonder if there has been a lot more pressure in the system than normal, possibly due to water pump failure? Did you ever notice the temp gauge running high?

When you fitted new tank did you use the built in bleed procedure (ignition on, hold accelerator pedal all way down for 30 secs)? I would be running an INPA diagnostic on the water pump if it were me.
 
I would check after all the above to see if the smoke clears. If not,then get a sniff check done on the coolant, as it may have failed due to over pressurisation of the cooling system due to a head gasket breach , which is rare but not impossible.
 
Having spent many years driving a track prepared Dolomite Sprint (which is well known for head gasket blows), try starting your engine and bring it to temp and squeeze the coolant pipes and if they are board hard it's a fair bet you have a gasket failure.
 
I would agree with the others who think there was a lot of pressure in the system to blow that apart, real possibility of a head gasket gone. Best run it up to temp with the cap off and see if there are bubbles appearing at the top. Alternative is to get a test kit and test for gas in the coolant, if there is that would confirm you have head gasket gone.
https://www.ebay.co.uk/itm/Combustion-Leak-Tester-Kit-Head-Gasket-Block-Detector-Blown-30ml-Petrol-Diesel/124392170566?hash=item1cf659e446:g:ERkAAOSwnVdfi3NL
 
Everyone above has made valid points but I would just balance that to say that N52 head gasket failure is virtually unheard of on here. In fact I don’t recall it ever being reported at all, so you would be very unlucky indeed.
 
Thank you for all your inputs. I will try squeeze the coolant pipes to see tomorrow.

But from what you are saying it sounds like head gasket.
When I was bleeding the system, the first time I started the engine, the coolant actually fountained out of the bleeder nozzle. I stopped the engine, refilled and cranked again, it did so again but less. I repeated a few times and each time it was easing till eventually just a few bubbles out of the bleeder

Is this all bad news then? Should it not bubble at all.
Quite new to all of this.

Appreciate the help.
 
Whilst it bleeds air out you will see bubbles escaping once up to temp if bubbles are still comming out then that may well be down to blown head gasket. When bleeding ensure you set the heater control to fully hot so coolant runs through the heater matrix and pushes any air out of that. Try and get the filler hole as high as you can either jack the front of the car up or drive it onto a pair of ramps. The gas testing kit I posted about earlier will show if its a blown head gasket.
 
Yup, purchased the tester now, so will check as soon as.
What do you think though, if it’s a head gasket is it a goner? Seeing some pretty horrific outcomes of this.
 
ph001 said:
Everyone above has made valid points but I would just balance that to say that N52 head gasket failure is virtually unheard of on here. In fact I don’t recall it ever being reported at all, so you would be very unlucky indeed.
Click to expand...
Bodgit and leggit on youtube show an N52 with HGF , caused by water pump failure. Do not ever drive if the gauge moves or alarms go off. He shows that the head lifts in the middle of the block between 3 and 4 cylinders. This then pulls the studs from the block and as a cost of repair with a replacement head ( too much to skim out ) and hellicoil on the block made it more cost efficient to replace the engine as a whole.
I do agree that HGF is rare but with cars changing hands and getting older, we all dont know what history these cars have had prior to the current owners. It was interesting due to the lack of failures here as to what can happen.
 
Thrustyjust said:
ph001 said:
Everyone above has made valid points but I would just balance that to say that N52 head gasket failure is virtually unheard of on here. In fact I don’t recall it ever being reported at all, so you would be very unlucky indeed.
Click to expand...
Bodgit and leggit on youtube show an N52 with HGF , caused by water pump failure. Do not ever drive if the gauge moves or alarms go off. He shows that the head lifts in the middle of the block between 3 and 4 cylinders. This then pulls the studs from the block and as a cost of repair with a replacement head ( too much to skim out ) and hellicoil on the block made it more cost efficient to replace the engine as a whole.
I do agree that HGF is rare but with cars changing hands and getting older, we all dont know what history these cars have had prior to the current owners. It was interesting due to the lack of failures here as to what can happen.
Click to expand...

Indeed, that’s why I mentioned water pump failure and asked the question to the OP but no response. Saying that, there have been several N52 water pump failures documented on here, even where people have continued driving and no resultant damage. The ecu seems to do a pretty good job of protecting it.

Shows it can happen though, if you are ignorant enough of all the warning lights!
 
I never noticed any temp getting high. Can water pump fail with temp staying consistently in the middle? I have always checked regularly though so doubt I’ve missed it.

Will keep you updated on the combustion gas test kit though. Should arrive in the next few days.
 
Lewischarlie_95 said:
I never noticed any temp getting high. Can water pump fail with temp staying consistently in the middle? I have always checked regularly though so doubt I’ve missed it.

Will keep you updated on the combustion gas test kit though. Should arrive in the next few days.
Click to expand...

If you have not had temperature issues then your pump is probably ok. The gauge goes into the red very quickly indeed when it stops!

I’d be very surprised if you have hg failure then.
 
I had awater pump go on my 1st E86 and one on my E91 and both times the temperature went from normal to the red in less than mile!

I was on an unlit NSL dual carriageway with no safe stopping place on a cold December night when my E86 one died so I took a chance and drove it as slowly as I could in 6th gear for 5 miles or so without any HG problem, although it did go into limp mode.

The only time I've heard of a big issue with an N52 was a forum member who had a water pump fail and ended up with a cracked block, but that was in a 130i that was on track when it happened so hopefully your HG is OK. :thumbsup:
 
Mine was changed by BMW just before I collected the car, turned out it wasn't fitted correctly and the bottom hose blew off when the wife was driving it about 2 weeks later. She drove 1.5 miles home, didn't look at the temp gauge :headbang: Who knows what temp it got to, refitted, refilled bled and been fine since, nearly 5 years.
 
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