Need Advice - Checking for Vacuum Leaks with Propane

[Tidybuoy]

I've read and heard that you can spray propane (un-lit) around the engine and detect vacuum leaks as the engine will rev when it sucks in propane. I guess this could also be done with other things like carb cleaner.

So, I bought a propane torch and tried this but I was afraid to turn the propane on too high and worried I might start a fire.

Can anyone tell me how you do this? I really want to check my air box for leaks. I've already replaced all hoses and injector seals but I have surging.

Thanks in advance for any advice.

[Ronnie's.930]

When I use propane to check for leaks, I slip a long section of hose over the end of the spout and put the hose in the area that I want to check (propane bottle in one hand and the hose in the other). I turn on the propane just enough so that I can see the gas trickling out of the end of the hose.

You won't start a fire unless you get the gas in the vicinity of an open flame or spark.

[redstrosekNic]

^+1

[Tidybuoy]

Thanks! I think adding the hose is a good idea.

[reachme]

I never had much success at this. A hose sounds good but it's difficult to get it really close into all the places you need to check, and close is very important if the gas is turned way down low. With fans blowing air around and the clear gas denser than air I missed the assurance that carb cleaner sprayed in a spot gave, and Carb cleaner on a cold engine was safe enough and worked better for me. Good luck

[jdbunda]

+1 on carb cleaner, that is what I have always used.

[tirwin]

Any particular reason you don't want to try the easy and safe way of using pressurized air? Tony (boyt911sc) has a post or two on how to do it and I have a link to it in my CIS for Dummies thread.

[jeffs9146]

I would recomend the vacuume test method!

When I was chasing vacuume leaks on my 83 3.0L I hooked up a small shop vac to the intake cone and put the hose on the blow side of the vacuume! Of course I cleaned the vacuume first! Then turn on the vacuume and spray soapy water over everything and watch the bubbles grow before your eyes!!

[Cajundaddy]

Originally Posted by jeffs9146

I would recomend the vacuume test method!

When I was chasing vacuume leaks on my 83 3.0L I hooked up a small shop vac to the intake cone and put the hose on the blow side of the vacuume! Of course I cleaned the vacuume first! Then turn on the vacuume and spray soapy water over everything and watch the bubbles grow before your eyes!!

^^^ Much safer than propane.

A simple coil arc can cause a propane flash fire that will cook you good.

[I'mThatGuy]

I personally like the smoke machine method and you can rent one at alot of parts stores these days (what you would do is plug pcv line, and make a dead head adapter: intake sleeve and a glue in pvc cap works well and pressurize the intake with the smoke) I've never had an intake leak, boost pipe leak or evap leak I couldnt find with the smoke machine method, but if you use the above method with the blower side of a shopvac I always mix up a spray bottle of dawn detergent and water to look for bubbles around gaskets, and for cracks in hoses, when I am shade treeing it somewhere....