Ever have a hard to find vacuum leak?

PineRidge · Jun 28, 2008

Vacuum leaks on cars, trucks, and the like can be a real PITA to find, even with the use of spray carb cleaner, which is also flammable presenting problems in itself.

Anyone here ever try to make a simple smoke generator to flood the vacuum lines and fittings as an easy way to find the leak, however small that it may be?

I'm thinking on some type of large metal can with a screw-on lid with long tubing attached so it can be connected to the manifold. Maybe even a mason jar.

Drop in a Superior smoke candle and quickly screw on the lid, which should flood the vacuum lines with smoke. Whadda all think, could it work?

I have seen commercial smoke generators that sell for thousands of dollars so this might be the poor man's advantage.

billbill1 · Jun 29, 2008

Mike to answer your thread title question, yes-many vacuum leaks that are hard to find. But sorry, I don't know if your idea will work. Please keep us posted on your results.

Renze · Jun 29, 2008

In Holland, there is a redneck rockband called Jovink, these guys are totally insane.

They used to drive around in a Limo, and for special effects, they used a windscreen sprayer pump to inject diesel fuel into the exhaust. The effect was huge clouds of white smoke, which might be perfect for what you're trying to do.. (the infamous limo, when retired, was used as projectile in a "car darts" game on one of their festivals.)

But will you use an endoscope to watch inside the vacuum tube where the smoke will come in ????

I think when pressurised, the vacuum hoses wont leak anymore...

Skyco · Jun 29, 2008

Renze said:
I think when pressurised, the vacuum hoses wont leak anymore...

That is a possible problem- some leaks can be one-way, they might leak under vacuum and not pressure or vice versa.

PineRidge · Jun 29, 2008

Renze said:
In Holland, there is a redneck rockband called Jovink, these guys are totally insane.

They used to drive around in a Limo, and for special effects, they used a windscreen sprayer pump to inject diesel fuel into the exhaust. The effect was huge clouds of white smoke, which might be perfect for what you're trying to do.. (the infamous limo, when retired, was used as projectile in a "car darts" game on one of their festivals.)

But will you use an endoscope to watch inside the vacuum tube where the smoke will come in ????

I think when pressurised, the vacuum hoses wont leak anymore...

Renze never thought of heating diesel to make smoke, that might not be a bad idea at all.

Figured if clear tubing was used between the smoke generator and the engine manifold one would be able to see the smoke entering the system.

Here's a really good article on vacuum leaks and using smoke to find them tech to tech

I still have a can of carb cleaner left so I'll see how this thing plays out today. If the carb cleaner gig doesn't do the job then smoke will follow. Maybe clouds of it.

ToadHill · Jun 29, 2008

It will work, when I worked in a repair shop we used to spray light oil on vacuum lines and attachment points and look for the smoke coming out the exhaust.

RonMar · Jun 29, 2008

I would think you would want to apply a little pressure. And for that matter, you could probably do away with the smoke all together. What are the main entrances and exits to the engine? The intake and the exhaust... Other than that, the system should be sealed. So you make up a plug to seal the intake, and another to seal up the exhaust. I have made ones up using PVC end caps that fit in the intake hose and are secured with a hose clamp. You can get expanding rubber plugs in the plumbing department of many hardware stores that will expand to fit the exhaust pipe.

Into the plug in the intake, since it is probably the easiest to get to, you drill and thread a hose fitting for an air hose. Using a regulator apply say 10-15 PSI to the now sealed system. Any more pressure than that could be hazardous, but 15 PSI should be plenty.

Using some kids bubble mix in a spray bottle(or make your own 50/50 mix dish soap and water with a little sugar), spray it on all the hoses and fitings. The escaping air at any leak point should make bubbles.

I have done this several times checking turbocharger and intercooler plumbing integrity. It only takes a few minutes to set up and is a pretty difinitive test for leakage.

Good luck

3RRL · Jun 29, 2008

Ron,
What is the little bit of sugar in soap mixture for?
To make the medicine go down?

RonMar · Jun 29, 2008

It makes the fluid a little sticky so formed bubbles persist and grow with air input. My wife just corrected me on my memory of the mix. The actual recipe for homemade bubble mix is 1/2 cup water, 6 tea spoons liquid dishsoap and 5 tea spoons of sugar...