BenzWorld Senior Member
Date registered: Jan 2005
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RE: 114/115 chassis vacuum diagram
Trans vacuum modulator is mounted at the rear end of the trans,depending on what model car you have the rear cross member sometimes conceals it.It's only about 2" diameter but you can't miss it.it has a hose leading into it.If you have the series 2 air con,the vacuum leak may be on the drivers side vacuum canister,it's about midway back from the dash and closes the heater off when the air is turned on .Try fitting a vacuum pump, i use a refrigeration enginners one,to the yelloow line leding into the firewall and listen while it runs,i doubt if a leak in these lines will cause the rough running,if anything the engine will idle TOO HIGH.To find a leak,run the engine ,spray ether engine start aerosol around the intake manifold ,if the engine speed changes you have found your leak.