Ever have a hard to find vacuum leak?

[GIJOE]

I've always used a bottle of propane or mapp gas that plumbers use for sweating pipe. Just crack the valve (don't light the torch) and trace the vacuum line with the tip of the torch. When the engine idle changes, you found your leak.

Joe

 

[donais]

gijoe thats how i used to do, its what they tought us in college....

 

[PineRidge]

I've always used a bottle of propane or mapp gas that plumbers use for sweating pipe. Just crack the valve (don't light the torch) and trace the vacuum line with the tip of the torch. When the engine idle changes, you found your leak.

Joe

I'm going to have to try your method GIJOE because my way isn't working at all, nosirrebob. Thought I had it when the PVC valve wouldn't rattle and the hose connected to it collapsed flat with vacuum when the engine was running. The short hose connected to it was soft and made me think for a minute that the job was done.

If I ever get another vacuum leak in my lifetime it will be too soon.

 

[SPIKER]

pineridge: good to see ya posting here again. it is one of the most nerve racking things finding vac leaks. my truck (also a ford) has one someplace too only a few years older than that pic. otherwise it runs like champ

propane an or starting fluid works best that i've found as long as all the factory air box stuff is attached, (I used small rag and or cotton balls coated it the stuff to keep it close to the line and work way around)
mark

 

[PineRidge]

Hey Spiker how ya doing? Had to put the van back together since we're taking it on a jont pulling an enclosed trailer the 3rs and 4th of this month.

Once we return guess I'll have to take it back apart and get back in the "find the leak" mode once again.

This Ford van has less than 100k miles and really is a sweet driving van. Just has that blasted nagging vacuum leak.

 

[skipmarcy]

I'm going to have to try your method GIJOE because my way isn't working at all, nosirrebob. Thought I had it when the PVC valve wouldn't rattle and the hose connected to it collapsed flat with vacuum when the engine was running. The short hose connected to it was soft and made me think for a minute that the job was done.

If I ever get another vacuum leak in my lifetime it will be too soon.

The propane works about the best, and to make it easier to use I have a little rig I bought years ago for about $10 that is a valve with about 18" of hose and a long aluminum tip. I think it was a KD tool. It even has a hanger on it to hang the bottle of LP from the hood latch. You crack the valve just ever so slightly and can direct the nozzle most anywhere, even bend it around stuff. I also had an expensive electronic detector that was good for vacuum leaks as well as bearing noises etc., had about 8 or 10 led's that lit up the closer to the noise you got.

 

[PineRidge]

The propane works about the best, and to make it easier to use I have a little rig I bought years ago for about $10 that is a valve with about 18" of hose and a long aluminum tip. I think it was a KD tool. It even has a hanger on it to hang the bottle of LP from the hood latch. You crack the valve just ever so slightly and can direct the nozzle most anywhere, even bend it around stuff. I also had an expensive electronic detector that was good for vacuum leaks as well as bearing noises etc., had about 8 or 10 led's that lit up the closer to the noise you got.

Did a Google search of "propane vacuum leak detector" and came up with this

I'm assuming this is similar to what you describe.

 

[Ranch_Hand_Supp]

The VacuTec machine has been on the market for awhile.

Here is a link from ASA.

Tech To Tech


Ronald
Ranch Hand Supply

 

[PILOON]

I've always used a bottle of propane or mapp gas that plumbers use for sweating pipe. Just crack the valve (don't light the torch) and trace the vacuum line with the tip of the torch. When the engine idle changes, you found your leak.

Joe

One mechanic I know simply uses a $10. plumber's torch with the tube cut off at about 2 inches over which he slipped on about a 3 ft length of rubber vacume line hose which he terminated with perhaps 10 inches of metal brake line bent for accessing difficult spots.

With the engine running at idle believe you me when propane is sucked in at the leak site you know you have found your leak!
The engine revs up to let you know the leak has been discovered! (and I do not mean just 100 RPM).
It is just as if someone hit the accelerator peddle!

Best example of the KISS method I have seen for a long time!

 

[AlanB]

Mike, I would look real hard at those hard plastic vacuum lines that go into the rubbery joints especially where they go through the wiring looms into the dash area.

I have some now on my 96 Ford that need changing.

I would go with the propane and tubing for what you are doing.

We just spent about a month hunting for "a" leak on one of our distillation units. Turned out to be a slew of small problems, took me forever to sort them out.

Found most under pressure but the pressure relief cracks at .5 PSI (go find the gauge for that)

Not sure I would do it on a vehicle, the propane works well, but what I finally did on the still was a radiator pressure testor plumbed in too the system to pressurize and leak detect solution.

On your van, you may also try putting a quicky home made cardboard or similar snorkel on the air intake to get your air pickup away and minimize false positives. Then flood (fire risk) the area with propane in quadrants to narrow down your search area. Or disconnect and plug to narrow it to a particular area. Either way, it is time consuming and aggravating.

What indication are you having that it is definetely a vacuum leak? Sometimes other things can appear to be that and not actually be the case.