Top hose collapsed

[Dosco]

Any ideas?

When cold the top water hose is nearly flat, after opening the headertank cap it partially returns to its normal roundish form.

I do not appear to be loosing coolant and the AntiFreeze was changed about a year ago. The engine runs at around its normal 80 degrees C and I 'see no steam' from anywhere!

 

[television]

I would not worry too much, as the engine cools down it creates a vacuum.

 

[Dosco]

I would not worry too much, as the engine cools down it creates a vacuum.

Thanks Malcolm - had visions of expensive repairs, which is something I want to avoid just before my travels

 

[David Nock]

Shouldn't the expansion system allow coolant to flow back into the engine system as it cools down? Doesn't it suggest a blocked vent or faulty cap or something?

 

[Dosco]

Shouldn't the expansion system allow coolant to flow back into the engine system as it cools down? Doesn't it suggest a blocked vent or faulty cap or something?

Thanks for that, will sort out a replacement cap.

 

[David Nock]

Thanks for that, will sort out a replacement cap.

Still plenty of 'rubbery feel' to the top hose? it's not got any pending splits or similar?

 

[wireman]

Best get a new hose on, the system will become partialy evacuated on cooling and this is causing the hose to fold up when it should not do.
The pressure cap will not normaly allow air into the tank under the slight vacuum which will occur every time the car cools, if it did there would be a loss of this damp air every time it warmed up and that would take some coolant with it.
If you are in any doubt replace the cap and hose.
The hose is of insertion contruction i.e. there is a woven textile insertion layer between two layers of rubber which provides great tensile stregnth to the hose walls, when the hose ages the bond betwixt the inner and outer layers becomes weak and the hose may suddenly split under normal operating pressure.
Engine loss is one possible outcome.

 

[Dosco]

"Still plenty of 'rubbery feel' to the top hose? it's not got any pending splits or similar?"

"Best get a new hose on, the system will become partially evacuated on cooling and this is causing the hose to fold up when it should not do".

Hose looked fine, no splits or cracks visible but I did in fact order one with the pressure cap 'just in case'

 

[Ellsy Tanners]

Is your car a ml with a v6 or v8 petrol?, if so this is very comman and i would say normal, dont ask me why but ive never seen one fail because if it!!

 

[television]

Is your car a ml with a v6 or v8 petrol?, if so this is very comman and i would say normal, dont ask me why but ive never seen one fail because if it!!

My thoughts too

 

[Dosco]

Is your car a ml with a v6 or v8 petrol?, if so this is very comman and i would say normal, dont ask me why but ive never seen one fail because if it!!

It is an W210 - E240 V6 Petrol.

 

[television]

It is an W210 - E240 V6 Petrol.

Leave it Dosco, its OK

 

[Dosco]

Leave it Dosco, its OK

Thanks for that Malcolm and all the other responses.

 

[television]

Thanks for that Malcolm and all the other responses.

If the hose is supple and soft thats good, its when its hard, then it more of a problem

 

[star]

This normally happens when you check the water level with a warm engine and the coolant contarcts when cools. release the cap when cold and retighten.

 

[Dosco]

If the hose is supple and soft thats good, its when its hard, then it more of a problem

I like that descriptor Malcolm however I have never found the latter part of your post a problem myself

However an update, I had purchased a new cap (all of £10) and can report that upon checking this morning the hose does not appear to have collapsed flat, and it is still 'supple and soft'.

 

[Dosco]

This normally happens when you check the water level with a warm engine and the coolant contarcts when cools. release the cap when cold and retighten.

Yep you might just have hit upon the real cause, I might very well have done what you say, thanks for your response.