Zum Thema bruechige Plastik-Kuehler

[Erich]

habe da gerade was gefunden, das evtl. Licht in die Sache bringt.
Nach diesem Kommentar werden die Dinger bruechig, wenn man vorher nicht auf den Fluessigkeitsstand geschaut hat.
blasen = heisser als die Fluessigkeit
quote

I just put a new radiator in my '88 735i. Same problem you are seeing. Paid $370Cdn for OEM "Aluminum core with plastic tanks". Check if yours is the same ("tanks" are the two ends, running the full height of the radiator). If your is this type, you may not have to replace the whole thing (though it may be worth it if it is old, crusty or unknown condition). If you have the plastic tanks that are clamped with a "wavy" flange, you have to get a complete new one. If the tanks are clamped with tabs that are bent over to hold it in place, you should be able to hunt around and find a shop that will swap the bad tank for you.

Here's the caveat and the warning. If you have plastic tanks, you have a superior-flow system. These are more efficient at cooling your engine. However, you MUST NOT let your coolant level to ever ride below the top of your tanks. If you do, the top of the tank gets a steam build-up. This steam "cooks" the plastic, making it VERY brittle and subject to cracks, etc., leading to premature failure. This is a serious problem easily avoided simply by keeping watch of your coolant level.

Note: it is not enough to rely on your OBC warning system. By the time it tells you that your coolant level is too low it's probably too late.

I ended up replacing my whole radiator because I knew it was junk when I completely removed the drain plug and had not even a drip of fluid come out of a completely full rad!

unquote

Die Diskussionen gehen weiter. Aber mal interessant, dass die Plastikdinger besser in der Kuehlung sein sollen.