Cooling system pulling a vacuum AFTER cooldown?
 

'85 V12 HE.

Cooling system works great - no leaks, stays well below the N even making the 2000 foot climb up the mountain to my house in 90-degree temps. No issues there.

What's odd is I'll come home and park it and the next morning, after the car cools back down, both upper radiator hoses will be sucked in and flat. They return to normal radiator hoses when the car's warm.

I thought that maybe the line into the coolant reservoir tank inside the driver's wing was blocked, so just for fun I deliberately overfilled the system. After warming up, coolant came running out of the correct spot onto the ground, so I know it's flowing to the bottle when needed and it's also able to get out of the bottle, so therefore I'm thinking air would also be able to get in, theoretically breaking the vacuum.

This really isn't causing any sort of an operating problem, I'm just figuring that over time this is going to stress my rad hoses and shorten their life.

Any ideas?

D

sounds like your radiator hoses already need refreshed.

Some manufacturers produce hoses with metal springs fitted inside the hose to alleviate "collapse" of the hose. Maybe that would help...

YEP, a couple spring to mind.

1) The radiator cap on the header tank is NOT releasing the little valve to allow flow FROM the atmospheric tank in the LH wing.

2) That atmospheric tank supply hose is blocked, COMMON.

3) That atmospheric tank is FULL of mud, VERY COMMON. So much so that the end of that small hose is stuck in the mud, and obviously it cannot suck the mud up, so the hoses collapse.

My suggestions are:

Remove the LHF wheel, remove the rear cover panel, remove the plastic tank inside, and clean the mud and stuff out of it. Half fill it with coolant prior to refitting.

Remove the hose from that tank to the header tank spigot, just under the cap, and ensure it is NOT blocked. Do what you gotta do. It MUST be clean 100%.

Replace the pressure cap on the header tank.

Bleed the cooling system PROPERLY.

ENJOY THE CAR.