[Bali]

There are so many requests for solving problems that usually start with "do a smoke test for vacuum leaks" that there's a real need to have a single thread dedicated to smoke testing. Then we can just post the link to this thread when someone needs smoke testing info. Please chime in with your tips, links, experience, etc., and I'll curate it all in this first post. I'd like to dedicate this thread to @jfoj for posting most of this information in various threads over the years. I plagiarized his posts heavily. 🙇

Smoke Testers

• Amazon.com: automotive smoke machine
• smoke test machine for sale | eBay
• Amazon.com: smoke test machine automotive
• https://forum.e46fanatics.com/showpost.php?p=18615591&postcount=144
• Smoke machine, finally
• Stinger Evap Smoke Machines OFFICIAL SITE - Affordable Professional Smoke Testing Machines For Car Smoke Tests - EvaporativeSmokeMachines.Com
• https://www.ecstuning.com/b-bav-aut...diagnostic-smoke-machine-smoker/b8800109~bav/

Tricks to Doing it Well

• start with a fully cold engine, some leaks go away with heat expansion of parts
• put the front end up on jack stands so you can get under it while looking for smoke
• remove all engine covers (top and bottom), air box, and anything else blocking good visibility all around the intake manifold (power steering reservoir, cabin microfilter tray, etc.)
• use a mechanics mirror and bright light to search for smoke
• open the oil filler cap while you pump lots of thick smoke into the intake until smoke is coming out the hole then replace it, that ensures smoke has filled the crankcase, keep pumping while you search for smoke leaks
• remove the one-way valve from the brake booster grommet, plug it well, then see if the STFTs go down

Common Leaks

1. Upper and lower intake boots
2. Upper intake boot around F connector
3. DISA main O-ring and shaft area
4. Vacuum hoses and plugs at the rear of the intake
5. Fuel pressure vent hose that connects to the F connector on the upper intake boot and under the drivers floor board where it connects to the fuel pressure regulator
6. CCV and hoses, especially the lower oil return line
7. Dipstick and dipstick guide tube
8. Oil fill cap
9. Valve cover gaskets and cracked valve covers
10. SAP vacuum line to Kombi valve on front of engine, this will not leak smoke because of the control valve under the rear of the intake
11. Power brake booster, sucking jet pump, and related hoses

Note that the brake booster usually cannot be smoke tested because of the input vacuum check valve at the booster connection.

Smoke Test Videos

BAVauto Diagnostic Smoker - P0171 and P0174 Smoke Test

How to Find Vacuum Leaks With a Cigar (Life Hack)

How to Make a Smoke Machine

BEST automotive smoke machine you can build

 

[RayPooley]

Made my own. Works great.

 

[76m2002]

I used homemade and then cheap smoke generators. Then I bought a Stinger Pro. only a few $ more than cheap machines, and much more reliable and easier to use. Well worth a few extra $ for the reliable tool.

 

[Bali]

I used homemade and then cheap smoke generators. Then I bought a Stinger Pro. only a few $ more than cheap machines, and much more reliable and easier to use. Well worth a few extra $ for the reliable tool.

Thanks! Added a link to the Stinger 2 as well as smoke testers on amazon and ebay.

 

[Spannerhead]

I used homemade and then cheap smoke generators. Then I bought a Stinger Pro. only a few $ more than cheap machines, and much more reliable and easier to use. Well worth a few extra $ for the reliable tool.

^This. I bought the cheaper Stinger model when the company offered it (they don't anymore I believe). Still one of the best tool purchases I've made:

Here's one of my smoke tests:

https://www.youtube.com/watch?v=qGcOepRgU6c



Here's a question I have that maybe you could put the info for in the top post: What diameter PVC cap should I buy to make a homemade plug for the upper intake boot? In the above test, I use a long funnel that I tape into place, but as you can see, it's not a perfect seal. Would be great to have a PVC cap or similar with a tapped fitting in the center; that way I can just use the boot's hose clamp and get a better seal.

I could just remove the MAF sensor and take it down to Home Depot to match it up, but if anyone has that info handy, it would save some hassle. Thanks!

 

[76m2002]

I just put a latex glove over the maf and insert the tubing through a hole in one of the fingers.

 

[RayPooley]

I just put a latex glove over the maf and insert the tubing through a hole in one of the fingers.

You don't want to be blowing smoke through your MAF. It will sh1t up the sensor wire. The glove thing will work just as well with the MAF removed.

 

[LL i am]

balidawg, i haven't seen whole video (just a fraction of the 1st), nor read the thread yet, but i liked your smoke machine, so simple, and looks so easy to use.

 

[LeverThis]

Here's a question I have that maybe you could put the info for in the top post: What diameter PVC cap should I buy to make a homemade plug for the upper intake boot? In the above test, I use a long funnel that I tape into place, but as you can see, it's not a perfect seal. Would be great to have a PVC cap or similar with a tapped fitting in the center; that way I can just use the boot's hose clamp and get a better seal.

I could just remove the MAF sensor and take it down to Home Depot to match it up, but if anyone has that info handy, it would save some hassle. Thanks!

Wouldn't it be better to take the intake boot with you to Home Depot, so to speak? Since that is what the pvc adapter will plug into to run the smoke test.

Edit: Maybe it doesn't really matter. I've thought about this as well. If a pvc pipe itself happens to fit in the intake boot, then that could also work if cut very short (like 2 inches) and then the corresponding end cap fitted over the end.

 

[Spannerhead]

Wouldn't it be better to take the intake boot with you to Home Depot, so to speak? Since that is what the pvc adapter will plug into to run the smoke test.

Edit: Maybe it doesn't really matter. I've thought about this as well. If a pvc pipe itself happens to fit in the intake boot, then that could also work if cut very short (like 2 inches) and then the corresponding end cap fitted over the end.

Maybe. It's just more convenient to take the MAF sensor than to remove the intake boot. I guess I could just measure the darn thing. :idea:

 

[Bali]

I just put a latex glove over the maf and insert the tubing through a hole in one of the fingers.

Yeah, this is what most people do. Because a latex glove can easily stretch and fit over various sized ports and the finger is perfect for connecting the smoke machine hose.

 

[Bali]

balidawg, i haven't seen whole video (just a fraction of the 1st), nor read the thread yet, but i liked your smoke machine, so simple, and looks so easy to use.

Thanks, but I cannot take credit for the simple smoke machine. I think it was jfoj’s post where I first saw it. Pretty much all the information here was taken from a bunch of threads I found when searching this forum for “smoke test”, so really a team effort.

 

[wfx32]

https://blog.bavauto.com/21598/bmw-fault-code-p0171-and-p0174-lean-bank-1-lean-bank-2/
https://www.ecstuning.com/b-bav-aut...diagnostic-smoke-machine-smoker/b8800109~bav/
https://www.youtube.com/watch?v=dfAkpEExnQc

i was thinking about this bavauto unit a few months ago. also some folks are recommending a theatrical fog machine.

 

[beechbmw]

Maybe. It's just more convenient to take the MAF sensor than to remove the intake boot. I guess I could just measure the darn thing. :idea:

I found that a 3" diameter piece of PVC pipe fits nicely into the intake boot with the MAF sensor removed. I then used the nitrile glove connection version over the other end of the piece of pipe sticking out of the intake boot where the MAF was to hook up to the Harbor Freight transfer pump version of a smoke machine.

I suppose that a 3" cap could be bought and glued onto the short piece of 3" diameter pipe and then drilled and tapped/threaded to install the appropriate barbed fitting for a hose to connect to a smoke machine. Just a thought.

 

[beechbmw]

BaliDawg:

I'm not familiar with the appropriate e46Fanatics etiquette for this suggestion, but here is a recent post from a forum member thread that has been selling smoke machines, first listing under his signature:

https://forum.e46fanatics.com/showpost.php?p=18615591&postcount=144


I'll leave it with you as to whether you want to put it in your compendium in your first post.

 

[Spannerhead]

https://blog.bavauto.com/21598/bmw-fault-code-p0171-and-p0174-lean-bank-1-lean-bank-2/
https://www.ecstuning.com/b-bav-aut...diagnostic-smoke-machine-smoker/b8800109~bav/

i was thinking about this bavauto unit a few months ago. also some folks are recommending a theatrical fog machine.

Way too expensive. Just get the Stinger unit for less than half the price.

I suppose that a 3" cap could be bought and glued onto the short piece of 3" diameter pipe and then drilled and tapped/threaded to install the appropriate barbed fitting for a hose to connect to a smoke machine. Just a thought.

Yeah that was the idea. Thanks for the input; 3" is a good place to start.

 

[beechbmw]

Wouldn't it be better to take the intake boot with you to Home Depot, so to speak? Since that is what the pvc adapter will plug into to run the smoke test.

Edit: Maybe it doesn't really matter. I've thought about this as well. If a pvc pipe itself happens to fit in the intake boot, then that could also work if cut very short (like 2 inches) and then the corresponding end cap fitted over the end.

I found that 3" diameter PVC pipe worked just fine for me.

 

[Bali]

https://blog.bavauto.com/21598/bmw-fault-code-p0171-and-p0174-lean-bank-1-lean-bank-2/
https://www.ecstuning.com/b-bav-aut...diagnostic-smoke-machine-smoker/b8800109~bav/

i was thinking about this bavauto unit a few months ago. also some folks are recommending a theatrical fog machine.

Good links, added. :thumbup:

Not sure about a theatrical fog machine. See if you can find some examples or discussion on that.

 

[DaHammer]

When all else fails, there is always Scotty's method.

https://www.youtube.com/watch?v=zMok2y05jNE

 

[Spannerhead]

I'm all for cheap-and-dirty DIYs (the cigar method, etc), but E46s being what they are, there's practically NO chance you'll only have to do just one smoke test. Might as well pay a little more for a robust, reusable tool.