'97 Coolant recovery question

When the engine is hot, excess coolant transfers to the coolant
recovery tank.
When the engine cools (overnight), the coolant does not return to the
radiator.
When I remove the radiator cap, I can tell I'm breaking a vacuum.
Is this a radiator cap problem? - Mike

It is a possibility... could also be a restriction in the hose to the
recovery tank...


> wrote in message
oups.com...
> When the engine is hot, excess coolant transfers to the coolant
> recovery tank.
> When the engine cools (overnight), the coolant does not return to the
> radiator.
> When I remove the radiator cap, I can tell I'm breaking a vacuum.
> Is this a radiator cap problem? - Mike
>

Well, beside hearing the vacuum when I release the cap, the upper
radiator hose has collapsed from the vacuum. Thinking it was weak I
replaced it (along with the radiator cap), but the symptom continues.

I removed the small line from the radiator filler neck to the recovery
tank and the vacuum remained in the radiator.

Open to suggestions - Mike