Vacuum leak in dash of 116
 

Wanted/needed:
- Tricks of the trade in search of a cockpit-underdash vacuum leak.
- Most likely candidate(s) as to the problem

1980 450SEL 150k miles.

Just started hearing a faint high pitch noise after shutdown. It disappears in a matter of 15-30 seconds. Depressing the push buttons of the a/c panel does affect the noise. It all makes sense to me as a vacuum leak as the vacuum tank gets pulled down to zero due to the leak.

Looking for high pressure leaks is easy, spray soapy water..... Vacuum leaks, ugh. Short of putting a constant vacuum on the mainline from the engine compartment and then clamping off lines until I get silence (and a stethoscope helps too). Any other tricks of the trade that can help would be appreciated

I am on my knees praying to the god of busted knuckles that it's not the diaphrams wayyyyy up under the dash.

Thanks.

I believe a vacuum lead connects to the Economy gauge on the dash, if you have one of those, is it working?

later

Moraine,

Thanks for sharing the experience. You've reminded me that on nasty/tough jobs, it is wise to replace like and similiar parts while one is in there.

How tough was removing the dash? Any does and don'ts?