Coolant leak & collapsed top hose when cold?

[Mozambique]

2010, V8, 205k km. Water pump and crossover pipes changed at 160k km. Original hoses.
So, checked the coolant level last week and it was down to the base of the reservoir. No obvs sign of leaks. Topped it up, drove for 5hrs and no coolant loss.
Added UV dye, and have pressure tester to try and find leak. -9degC over night. Went out this morning and the top hose was collapsed as if under vacuum? Opened reservoir cap and no change. Coolant level now 1.5in. Above max fill line.

Thoughts anyone?

 

[txfromwi]

You opened the reservoir and the hose remained collapsed??

Your work was done 45K ago?

If the work was recent, this sounds like air bubbles from an improper evacuation and refill, but that's a long time for air bubbles to make their way out...

I would not be concerned about a bit of extra coolant in the reservoir - especially because you seem to have something going on.

 

[itsaguything]

Well, it may remain collapsed as it's cold. When it heats up it will be fine.
Good call in overfilling the reservoir. After a run, it should equalize.

But the larger point is at 45k, its getting to be time for a fluid change.

 

[Mozambique]

Yes, coolant system work done 4yrs ago.
I am not so concerned about the extra coolant per se. It's more the erratic behaviour. Yes, opened reservoir cap and the hose remained collapsed. It can't be extra coolant as the level was normal during two days of driving. Seems like a big air bubble in system giving the appearance of extra coolant, which is consistent with a leak somewhere, but doesn't explain the collapsed hose

 

[Mozambique]

Well, it may remain collapsed as it's cold. When it heats up it will be fine.
Good call in overfilling the reservoir. After a run, it should equalize.

But the larger point is at 45k, its getting to be time for a fluid change.

Didn't overfill the reservoir. I suspect air in system re. Leak. Coolant has been changed within past 4yrs

 

[txfromwi]

Leaks can be challenging to find - even with UV.

When you change out coolant next time use Rover coolant - it already contains UV dye and then you don't have the possibilities of added UV dye being incompatible with the coolant - (I only use those "universal" dye's if I am desperate.)

What's the chance that it's a head gasket and you are burning it off? Any white exhaust?

 

[Mozambique]

I used AC Delco dex-cool compatible dye.
Yes, head gasket leak has occurred to me. Checked for white smoke - none. No mayo on oil cap either.
Weather crappy at present so no chance to try and ID leak source.
Note that the fan does have a slight wobble. Does that sound normal, or water pump going (leak source?). I did briefly shine the UV lamp at the front water pump, hose area. No obvs iridescence.

 

[itsaguything]

I did marginally overfill my reservoir purposely in the hopes of filling any air pocket.... and it stays that way without issue or overflowing.

 

[jlglr4]

Once the coolant level gets that low in the reservoir, air gets into the system (might already have been in the system). I’d start with a complete bleed of the system and then start tracking coolant loss. You’ll never have a good idea of coolant loss until you bleed it out, and filling the coolant reservoir will not get the air out.

Bleeding it out should get rid of the collapsed tube. Just keep topping it up until you find the leak. If you can’t find the leak, I’d test for combustion gasses in the coolant after driving it for a while.

 

[txfromwi]

Agreed, if the reservoir really got low enough to suck in air, simply adding coolant will never burp the bubble - re-evacuate and refill as appropriate.

Hopefully your added dye is OK - personally I don't care what any additives CLAIM - I use them only when desperate, only those that claim "universal compatible", and then only when I am planning to immediately change out the fluid.
Just saying' - Rover coolant already has UV dye incorporated into it.