I just replaced the coolant expansion tank and overflow hose in my 1989 300E. When I removed the right front wheel and well cover to thread the new overflow hose through, I realized there was no overflow tank installed. Only the mounting brackets were there.

I am planning to get a tank and install it. However, my service manual CD isn't real clear. It shows a "vacuum reservoir" and the overflow tank.

1- Are there any potential problems related to not having the tank installed, other than venting overflow antifreeze into my wheel well?

2- What function does the vacuum reservoir serve? It isn't even mentioned in the 124 Cooling System Circuit diagram.

If anyone has a digital photo of the installed assembly they could email me, I would appreciate it.

Thanks for your help.