I apologize for what is likely an error in my previous post. Your 2.6 is similar in many ways to my 3.0
The overflow hose on your 2.6 may not feed into a tube coming off the cap neck as does mine. If that's so, then determining whether you have a faulty cap, neck, or overflow hose may be easier in your situation.
1991 300-SEL - Model 126
M103 - SOHC
James Madison - Oppressors can tyrannize only when they achieve a standing army, an enslaved press, and a disarmed populace.
Liberty Firearms Training - After years of trying to regulate California criminals with a never ending stream of gun control laws they have still not given up with the belief that if they make something a crime that criminals will miraculously start obeying the law.