atg614

Yes I will check that out. thanks

johnkk

Get a propane torch and turn on the gas but don't light! Let the engine idle and direct the flow around the whole intake and vacuum line circuits. When the idle speed increases, you've identified the vicinity of the leak.

tester123

Saw this trick being mentioned in many forums and repair advices online and can't speak for others but I didn't have any success with it whatsoever. I opened the propane valve completely and even put it directly to air intake -still no increase in rpms!

What did work is with engine off, slowly pressurize (no more than 10 psi) with compressed air each of vacuum / intake sections (i.e. breather hoses etc.) and listen for "hiss"; found a leak by camshaft adjuster gasket and half-moon seals on both sides.

Another method IMO is far more effective is to build a simple smoke machine from a glow plug in a sealed metal can (you can use cheap metal water bottles for example) filled above the plug with pure mineral oil, couple hose fittings from home depot, one for compressed air input and another for smoke output. You can buy hoses of different sizes from auto parts store. Connect the glow-plug to a 12v battery charger (external) and when smoke is being generated, slowly introduce compressed air. The output smoke can be then connected via another hose to section/area(s) in question and you will definitely see the smoke come out if there is a leak.

Just be careful, the metal bottle will get very hot

I built this all under $25 with most parts from home depot and in less than 1 hour. (see my rudimentary pic)

Just sharing my thoughts...

atg614

Where on a 2002 Audi A6 2.7 are the breather hoses located?

What are they anyway? Is it the intake?

There are so many hoses, I get lost.

atg614

This is what I replaced recently, is this the breather hose your talking about? If it is where do I place air pressure or smoke?

johnkk

The propane won't work in the intake because at idle the butterfly is closed. The propane works fine for vacuum leaks at assorted hoses and connections after the intake butterfly.

tester123

Thank you, I learned something today. When I was troubleshooting possible vacuum leaks, I tried that trick and was not successful hence, the concoction of smoke through glow plug. But, I'll keep in mind what you mentioned here.

Prospeeder

I found alot these newer cars do not react the same when trying to use a fuel source to find the air leak. I use brake cleaner, and watch the scan tool on live data at short term fuel trim. As soon as i spray where the leak is, it will go from Adding tons of fuel (lean condition) to subtracting fuel (rich condition you created) There usually is no change in how the engine runs, thats how seamless the management systems in these are.

icks90

Would all the little hoses at the back of the engine around the egr valves, sai and such like also affect the idle / vac leak issues?
You know, all the little pipes that are almost impossible to get to........