1985 K100 Vacuum Leak

[smith913]

Hey brickers,

I have been working on fixing my vacuum leak for some time now.  I have replaced every bit of rubber imaginable and sealed gaps where needed, but im still getting a "bad" reading on idle. 
I recently noticed a plastic cap on the throttle bodies is melted.  All i can make out on it is "6/15"
Does anyone know what this is and if it would cause a leak?

[TimTyler]

I don't have any caps on the front side of my TB's.

[bmw-rider]

just the end cap on the throttlebody

[rbm]

+1 it's a dust cover only.  The other end of the TB has O-rings on the end of the pivot shaft that connects with the TPS.  Check for leakage in that area if you haven't already.

[smith913]

Thanks for the input guys,  Ill look into replacing the dust cover at least.  the only other place with a small leak is where the manifold meets the block. 
any other ideas that would show similar symptoms as a vacuum leak?

[F14CRAZY]

How are you checking for vacuum leaks? I spray starting fluid onto areas it might occur while idling (I'm sure others will say not to do that, and with good reason, but)

[smith913]

ha yup, thats how im checking for them as well