DIY smoke machine for finding vacuum leaks?

[brockstar]

Howdy,

I've been wondering about and searching the internet for a smoke machine. I have an old Audi that has to have a vacuum leak. A smoke machine sounds very appealing to source, but being cheap, I don't want to spend $800 or more buying one. I'm not so interested in the propane or card cleaner methods.

I found this write-up but not much else:
http://forum.e46fanatics.com/showthr...+smoke+machine

Thoughts, suggestions?

[garfunkle24]

Can of ether's not cutting it?

[brockstar]

Nope. Engine wont start and isnt developing enough vacuum to raise the metering plate in the fuel distributor.

That and I want a smoke machine without having to pay much for it

[Mike83]

I need a smoke test too. I think I have an engine vacuum leak and also a small leak in the EVAP system. No point in throwing parts at it, plus don't want to pay $75 or so for a shop to test it. I'll let you know if I find anything.

[Tarheelgarage]

The problem with a homebrew smoke machine would be pressure control. It needs to be no more than 2psi or there is a risk of blowing out seals.

BTW, I have the Redline Total tech machine in my shop. Makes a lot of money finding the leaks plus saves time.

You would be surprised all the leaks a car will have.

[Blacknwhitepit]

From a prior thread.

Originally Posted by Piper

Hi

I had to replace 3 rubber flex lines on my jeep that go to the exhaust vapor canister. I was getting the dreaded check engine light on for a slow emissions leak. Anyway, I found 1 bad tube, replaced it but couldn't find the other leak which the dealer was able to. The service guy said they have a "smoke test" tool. I assume this means they have some sort of compressed smoke which leaks out and you can see where the leak is? My question is, is there a back yard mechanic version of this?

I replaced the worst tube for $3.60. The shop charged me $126.00 to do the other 2. Now granted I could have done all 3 but wasn't sure if this was the problem.

Any info appreciated.

Piper

Yes,

There is a "back yard mechanic technique". I did it to find my exhaust leak and later a vacuum leak. I went to a party shop and bought a Party Smoke machine for $29.99.

This is one, but it is more expensive:

http://www.diamondlakerental.com/images/FogMachine.jpg

I put a Rubber hose on it and then reduced or increase it to the size of the orifice I was testing. In this case an exhaust. I ran the smoke through the tail pipe and voilla! smoke came out of my exhaust donut location, not the exhaust manifold (like I expected). The fog juice runs about $8 a quart and lasts a while. This fog machine is even fun to have around for holloween. And this stuff runs on the same fog stuff that the expensive machines use!
To find a vacuum leak, just make sure the car is not running and hook it into the intake manifold (I used the intake manifold vacuum connector that goes to brake booster, it is usually a pretty good size.) Blast the smoke thru and you will see it come out of the leaking hose!


For an even more backyard way(and this is for a vacuum leak) is to run the car and use an unlit propane/butane torch. When the vacuum sucks it up you will hear an audible increase in the vehicles rpms and can "pinpoint" leaks that way.

-BWP

[Truxx1956]

Yep, the Halloween smoke fog machine is what I use and it works GREAT. Cheap too (just like me)

[brockstar]

Thanks!!

One question, I understand these burn a glycol or a mineral oil solution - would there be a concern with residue if I use this in a vacuum line?

I'm picturing everything getting coated internally and anything that come out of a broken line getting oily. But I'm probably exaggerating it in my mind..

[billymade]

http://www.google.com/products?hl=en...=next&start=10

[brockstar]

doh!

Thank you sir! I tend to overlook the basics..

[rhandwor]

I have found a lot of vacuum leaks on intakes and other areas. I use a can of carb. cleaner and spray along the edges of the intake if you hit a leak the engine will smooth out.

[m302483]

Has anyone tried this on EVAP lines? I'm assuming that this work work just as well if I modify somethign to pump the fog in to the filler.

Thanks

[Mike83]

Originally Posted by m302483

Has anyone tried this on EVAP lines? I'm assuming that this work work just as well if I modify somethign to pump the fog in to the filler.

Thanks

I would be concerned that if the fog is water based that you would get condensation/water in the tank and ruin your gasoline. I wonder too since I have an EVAP leak.

[norry]

Originally Posted by rhandwor

I have found a lot of vacuum leaks on intakes and other areas. I use a can of carb. cleaner and spray along the edges of the intake if you hit a leak the engine will smooth out.

Ether's probably better than carb cleaner for this - it evaporates very quickly, so it shouldn't cause any lasting damage to rubber. Spray a l-i-t-t-l-e at a time; you don't want to have a big, explosive cloud of ether hanging around in the engine compartment.

Worked like a charm in diagnosing a bad intake manifold gasket on an old E30.

[glasses97]

I am in the process of completing my smoke machine. It is every bit a functional as the professional models. I made the body out of 2 pieces of 3 inch diameter abs sewer pipe, a coupling, cap and a clean out. I used utility box covers for the plates inside that the wick mounts too. I used 18 inches of heating wire from an old dryer element, I wound the wire into two coils (9" each) around a 3/4 inch bolt to form them. My prototype only had one wick but I was getting carbonization of the top part of the wick. I got two wicks from those outdoor torches 7/8 inch diameter by 8 inchs long. I used a propane regulator to control the pressure. I just grabed it off an old bbq at the dump. The requlate the pressure to aprox 11" water column, mine puts out about 13 in wc. If you want to have a adjustable pressure get a regulator off of a disposable propane cylinder. They are usually adjustable from 5" to 17". You want around 13" water column. I also used the orifice off of the scrap bbq and drilled it out to 3/32 of an inch to limit the flow of the smoke. I found if I had to much flow it picked up an oil mist and carried it with the smoke. I used a chunk of clear tube to make a u-tube manometer. It is a very accurate way to measure water column it also serves as a relief valve. If the regulator fails it will blow the water out of the u-tube and vent the system, saving the cars systems. A flow gauge can be obtained from omega.com for just under $100, I have not purchased one yet. If you do go with the flow gauge (rotometer) you can also purchase orifices to "calibrate it for the differents size leaks" very cheap from a pneumatic store. I will posts some pics on line in the next few days for anybody that wants to see what it looks like. The total cost without the flow gauge is under $40.
Almost forgot, my system is powered from a old computer powersupply at 5 volts and about 5 1/2 amps.

[tonydanzah]

Originally Posted by Mike83

I would be concerned that if the fog is water based that you would get condensation/water in the tank and ruin your gasoline. I wonder too since I have an EVAP leak.

doubt it, would take a long time for you to accumulate that much water.

[Papawrench]

Ur answer is that it doesn't matter because u need a scan tool to close the vent valve or it will dump right out into the air u won't actualy get the evap system tested at all

[Toolhorder]

Originally Posted by Papawrench

Ur answer is that it doesn't matter because u need a scan tool to close the vent valve or it will dump right out into the air u won't actualy get the evap system tested at all

There are ways around that. A power probe and a hose clamp tool.
I never used a smoke machine at the dealer and hardly ever used the factory tool. We had a model that had a problem with the filler tube leaking. I used to stuff rags into a rubber glove and stuff it into the top of the tube and use a vacuum tester for the bottom and see if it held or not to test them.

I'd like to see the plans of the guy above who built a prototype. I want my own.

[Joelfke]

Originally Posted by Mike83

I need a smoke test too. I think I have an engine vacuum leak and also a small leak in the EVAP system. No point in throwing parts at it, plus don't want to pay $75 or so for a shop to test it. I'll let you know if I find anything.

any chance you have a late model GM car or truck? the vent valves in those die and crack all the time. I just had to replace mine in my 04 monte carlo. Not saying to throw a vent valve at it just saying its a common failure

[Joelfke]

Originally Posted by Mike83

I would be concerned that if the fog is water based that you would get condensation/water in the tank and ruin your gasoline. I wonder too since I have an EVAP leak.

the screen in newer gas tanks / fuel pumps allow for gas to only be pulled through even if there is water in the tank. unless all you have left IS water...then it will suck the water through