Why does upper radiator hose collapse?

[16valex]

Just happened to notice the wife's 97-528I upper radiator hose collapsed this morning, the engine was cold, so I went to remove the cap on the expansion tank and it slowly popped back out.

Here is what I'm thinking
Bad radiator cap.
Clogged expansion tank return hose.
Clogged thermostat housing relieve passage.

I'll run to the dealer to get a cap today and see how this go. Any other ideas are welcome. Thanks for reading.

[bimmerfiver]

At the least I would replace the cap and the upper hose which was collapsed.

Was the level of coolant okay when you opened the cap?

Cap and upper hose, then keep an eye on it.

[Jason5driver]

Possibly something clogged in your thermostat housing?

[16valex]

At the least I would replace the cap and the upper hose which was collapsed.

Was the level of coolant okay when you opened the cap?

Cap and upper hose, then keep an eye on it.

Okay, new cap and upper hose is replaced then a quick cold bleed procedure went for ride, all is fine at the moment. But in order to see if the cap is the culprit I have to wait for the engine to cool down completely, be back in a few hours.

BTW Bimmerfiver, the cooling level was fine, thanks for the reply.

[16valex]

Possibly something clogged in your thermostat housing?

It's possible, but hope not, I really don't want to go there today, just put in a new cap so let's see.

[Dualnames]

When was the last time you replaced it if ever? I have had mine explode once. Not pretty. I know that has nothing to do with it collapsing, just saying .

[bimmerfiver]

Brother it is amazing what you can find. An Albany club for this:

http://www.albanyscenarioclub.org/main/node/132

And Facebook for this:

www.facebook.com/pages/HAN-SOLO-Hoth.../31106998026

Han: Deck Officer! Deck Officer!
Deck Officer: Yes Captain Solo.
Han: Has Captain Skywalker reported in yet?
Deck Officer: No, not yet---but he may have reported in on the east entrance.
Han: May have reported in? Why don't you go check? My friend is out there and it's getting cold.
Deck Officer: Yes Sir.

Later...Han must leave and face the deadly weather on Planet Hoth to search for his friend, Luke. The Deck Officer tells him how cold it is---

Han: (Hoth Battle Gear): "That's right and my friend's out in it."
Deck Officer: "Your Tauntaun will freeze before you reach the first marker."
Han: Then I'll see you in Hell!

[16valex]

Good news, it's been over four hours since the engine was shut off and so far no collapsing of upper hose, I can't believe a cap can cause such problem. You guys better buy OEM or end up like me, that cap in there only a year old.

Brother it is amazing what you can find. An Albany club for this:

Bimmerfiver, sound like you want to join the club.

When was the last time you replaced it if ever? I have had mine explode once. Not pretty. I know that has nothing to do with it collapsing, just saying .

I replaced it once around 140K, car now has 173K miles. But I hear you brother.

[cnn]

The Radiator Cap in gasoline engine has 2 features:

1. It helps hold pressure until a set point when it allows pressurized air to come out. Usually set at 2 bars or so.

2. When engine cools down, it must allow air to re-enter the cooling system to return to "zero" pressure state.

Look at the tiny flap inside the radiator cap and you will see.

When feature #2 fails, you get collapsed hose.

This is an entertaining thread to read through:
http://www.thecj2apage.com/forums/co...topic2879.html