Smoking for vac leaks - how reliable?

[D60]

How reliable have you found a smoke machine to be for finding vac leaks?

I'm dealing with a vehicle right now that I swear has a vac leak based upon codes, process of elimination and the fact I'm convinced I hear a leak but I canNOT seem to chase down that stupid hiss no matter what I poke push, pull, prod, disconnect, fold, spindle or mutilate.

I smoked it heavily with my smoke machine (Proline, maybe) and NOTHING.

Have you had instances where smoking has failed you, or am I just chasing my tail?

 

[Silver]

I've got the same issue with a vehicle. I know smoke leaves the worst oil residue inside though. Maybe I'm using too much oil.

 

[DriveHard]

I thought one old-school method was to use a flammable spray - when the idle picked up from the added fuel, you found the leak?
(unlit propane torch - just the gas)

 

[Brian123]

How reliable have you found a smoke machine to be for finding vac leaks?

I'm dealing with a vehicle right now that I swear has a vac leak based upon codes, process of elimination and the fact I'm convinced I hear a leak but I canNOT seem to chase down that stupid hiss no matter what I poke push, pull, prod, disconnect, fold, spindle or mutilate.

I smoked it heavily with my smoke machine (Proline, maybe) and NOTHING.

Have you had instances where smoking has failed you, or am I just chasing my tail?

Back in the day I would just replace all of the Vacuum Lines! But maybe you have another issue!

 

[D60]

Back in the day I would just replace all of the Vacuum Lines! But maybe you have another issue!

That's actually what I want to do but have difficulty justifying it to my customer, esp if I can't PROVE to myself it's the issue.

There's a supplier that puts together all the vac hoses for $250 for the kit. There's quite a few hoses, several with tight 90's or differing diameters at each end, so bulk vac hose is not a realistic (or professional) option here.

But I'm uncomfortable going out on a limb for a $250 "part". I want evidence of where that **** leak is....although it could be several small leaks

 

[D60]

I thought one old-school method was to use a flammable spray - when the idle picked up from the added fuel, you found the leak?
(unlit propane torch - just the gas)

I've personally had zero success with that approach ever, but maybe it works for some people sometimes

 

[Brian123]

That's actually what I want to do but have difficulty justifying it to my customer, esp if I can't PROVE to myself it's the issue.

There's a supplier that puts together all the vac hoses for $250 for the kit. There's quite a few hoses, several with tight 90's or differing diameters at each end, so bulk vac hose is not a realistic (or professional) option here.

But I'm uncomfortable going out on a limb for a $250 "part". I want evidence of where that **** leak is....although it could be several small leaks

I did not realize that this is a vehicle you are doing for a customer. Is this a Volkswagon?

 

[Puhdantic]

You can search for EVAP leak/error code videos that South Main Auto has done. It seems to be helpful from the cases I've seen him use it in.

 

[clinebarger]

Year, Make, Model?
DTC's?

 

[clinebarger]

My post really didn't fit your question......Smoke testing is just another tool in the arsenal & works well most times, But doesn't always find the leak.

*Brake Booster leaks are easily overlooked because the check valve. I usually clamp the vacuum line to the Booster first thing & watch the Fuel Trims to see if they correct before ever pulling out the smoke machine.

*If a vacuum leak is on the other side of a Solenoid, You'll need to smoke the other side.

 

[Marcozi]

I thought one old-school method was to use a flammable spray - when the idle picked up from the added fuel, you found the leak?
(unlit propane torch - just the gas)

That doesn't always work.

 

[GSCJR]

If a vacuum leak is on the other side of a Solenoid, You'll need to smoke the other side.

+1

 

[JTK]

If a solenoid is failed open on the EVAP system (causing the MIL), you may not see smoke until it comes out the filler neck, air cleaner housing or canister vent to atmosphere.