Disclaimer: I have never tried either of these methods, nor am I proposing either method be used, but it seemed to work good.


Who has tried either of the methods mentioned in this video? Propane vs. starting fluid? Pros or Cons?

I want to track down a vacuum leak and all I've ever used was soapy water... Not that it would create bubbles since its a vacuum leak, but I'd see the bubbles getting sucked in.

 

You don't find vacuum leaks.... Vacuum leaks find you..........

 

On this topic, I have a (theoretical & practical) question

My OBD2 reader is permanently connected and reads manifold vacuum

If I establish normal vacuum at idle baseline (which is ~22 from memory)..via Torque free APP on my phone

Do you think that a small broken or detached line would cause a measurable drop in this baseline figure ?

I havent tried this yet, but have used a vacuum gauge in the past for engine diagnosis, and they will show a more serious vacuum leak

 

One could only imagine so. I have an OBDII reader also that I can use with my phone via bluetooth, maybe I could hook mine up to see if its off from "normal vacuum".
Its an HVAC leak I believe I have, but no proof really. I just feel like my HVAC controls aren't doing what I tell them to do sometimes. Maybe I'm wrong. My heat seems to be a little lacking, and it takes a while to get nice and toasty in the cab, making me wonder what's going on.

 

Eric makes good videos. Subscribed. Also very good is South Main Auto. Subscribed.

I've used carb cleaner several times and it works well if the leak isn't too tiny. It the leak is that small, you probably wouldn't be looking for it in the first place. The down side is it is very easy to use too much and it spreads all over so it's hard to be accurate with the location for some things like an old school V8 intake. Also, don't burn down your car.

I've used propane once because I didn't have any carb clean handy, and once because I was trying to be more precise with a tricky leak. I'd say it isn't quite as sensitive at finding leaks, but it's also safer.

I also like to use about three feet of one inch coolant hose held to my ear to listen for things, but that is only for fairly large leaks on fairly quiet engines and around my house I can only do that later at night because of the road noise.

Top notch, but pricey and complicated in some cases is a smoke machine.

I run torque all the time on my Subaru, and I have a mechanical vacuum gauge in my Volare, but the leak would have to be pretty bad for that to show up a leak. I can use them to tell the weather somewhat, and I can use them to tell where I am around town by the altimeter effect, but most people don't live where there is so much vertical. But with attention you can build up a baseline over time and conditions that will help diagnose problems when they come up.

 

I would think propane would be a little more difficult to use since you'll have the mechanical fan blowing around in the engine bay, so that could blow the propane gas away from where you're trying to get it to go, hence it wont be sucked into the vacuum leak.... personally, I guess I would use either one, and be smart about using the carb cleaner!!

 

Good point. I forgot to mention when I was using propane I had a huge piece of flattened box that I slipped in there to block the wind from the fan. But that was on my classic V8. Fitting the cardboard into the jeep bay might be more difficult.