545 Guy

The problem is that my header tank for the cooling system blew apart due to excess pressure on my 545 2005 model !! The only warning or previous symptom was just slowly losing coolant to which the warning notice on the dashboard was comming on. Asked the dealer about losing coolant and they had not heard of a problem!!!
So is it my head gasket?
Can anyone help?

Thanks.

turboawd

did you mean expansion tank?

545 Guy

Yep! Sorry do not know what I put down but thats what I meant. Thanks.

olskooldj

My expansion tank blew-up as well. It was preceded by high temp warning.
Bottom line, it was replaced no charge.

B_Schnell

This is the first I have heard of the 545i coolant expansion tank blowing due to excessive pressure? What causes that? Are you sure the leak is not from the O ring inside the coolant pipe in the cylinder head? Hope not as this is a very expensive fix. Was a recall and covered under warranty. There are several postings regarding this and a mechanic close to Carlsbad CA I believe that came up with a much less expensive fix only about $1,700 vs over 6,000 by the dealer who removes the engine. The O ring in my car went out at about 40,000 mi and was leaking about a gallon of coolant a week. The dealer had my care for over a week. They said they had to remove the engine to fix. Luckily was covered under the warranty. Hope this is not your problem. Any feedback on the expansion tank blowing appreciated???

luigi524td

Normally the pressures that develop in the cooling system are not high enough to cause a bursting of the reserve or overflow tanks. And, if the pressure cap is working properly, it should release pressure before any parts blow. I am aware that head gasket failure can cause sudden increases in pressure that the cooling system pressure cap can't react to quickly enough and the weakest links in the system (overflow tanks / hoses) may be the victims.

Is that what your mechanic is saying happened?

545 Guy

Just a quick note, BMW say there is not a problem other than the expantion tank failing !!!
Good news then.... lets wait and see...

Still a lovely machine...

pukka

The only way an expansion tank could fail like that is either its structual integrity got too weak over time or if there was too much coolant in it.

S62FAN

The expansion tanks in older BMW's should be preventively replaced after 60K miles especially in the V-8 models. Check out any E-38 or E-39 forum, there are tons of posts about them failing along with the radiators, exploding plastic fans etc.. Why BMW uses such lousy quality cooling parts is beyond me.