Vacuum leak testing the RIGHT way!

[ponkotsu]

I've suspected I had a vacuum leak, but couldn't find it. I first tried using carb cleaner, but no luck. Then I tried using propane, and nothing. So I decided to test my test. I injected propane directly into a vacuum line, and literally could not hear any change in the engine at all. I had to spray carb cleaner directly into the vacuum supply to make the engine speed change. Pumping propane directly into a vacuum line had no effect at all. Seems that the carb cleaner test doesn't work so well on modern engines. I've read other reports about that being a highly unreliable method. Apparently the engines are constantly updating engine speed so it's really hard to make these methods work. You need to use more sophisticated techniques like monitoring the O2 sensor outpout, etc, which really sounds like too much trouble.

So, I made a DIY smoke tester. Really simple. An empty paint can with a glow plug screwed into the side, and an in and out barb fitting. Fill with mineral oil to just below the level of the glow plug. Connect glow plug to the battery charger and give it a little shake once in a while. Connected it to my air compressor with as little pressure as possible. (2-5psi).

The smoke tester took one trip to the hardware store and about 20 minutes of time to build. It works tons better than spraying with carb cleaner or propane. Sure enough, my IAC was leaking like an NSA intern. I had sprayed carb cleaner and propane all around that area and nothing happened. I also found a couple of minor leaks but the main culprit was the IAC. That would certainly explain my hunting idle. I'll order the part and hopefully that fixes it.

The IAC leak was actually so bad I didn't even need smoke. I could hear it hissing clear as day.

 

[Tbars4]

..a video of fhis in use would be awesome..

 

[colintrax]

Mind posting some pictures? I got a leak to find.
Btw hose water has worked good for me

 

[ponkotsu]

Here's a video of the smoke exiting my IAC. The blue is RTV silicone. I made a feeble attempt to seal it up. It was leaking so bad it made it hard to find other leaks.



I'll upload pictures of my device later. It's super simple and cost about $20.

 

[colintrax]

Awesome! Thanks

 

[Tbars4]

...I fixed the video for ya so it can be watched from your thread..

 

[ponkotsu]

Pictures of the paint can smoker. I'd suggest having an extinguisher handy when doing this. And use oil with a high flash point. I used mineral oil.

 

[colintrax]

I donno much about glow plugs, any I should/shouldn't use? Would a rc car (nitro) plug work just as good?

 

[ponkotsu]

I donno much about glow plugs, any I should/shouldn't use? Would a rc car (nitro) plug work just as good?

Not sure an RC plug would make enough smoke. That just happened to be the only glow plug that Advance Auto had in stock. It has a lot of surface area and gets red hot so makes lots of smoke.

 

[colintrax]

Ah ok, didn't think about that. Yeah an rc plug prob won't work. Pretty small