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Username Post: Made a homemade Smoke Machine for Vacuum leaks        (Topic#223962)
74elco for73SS 
Senior Member
Posts: 575
74elco for73SS
Loc: so cal
Reg: 04-30-04
08-17-09 06:58 PM - Post#1755878    

If anyone is interested in perfecting this, I found a way to create a cheap smoke machine like auto shops use to pump smoke into your intake to find vacuum leaks. Find the smoke, find the vacuum leak.

Instead of paying around $1000, you can build one for around $35 or so.

Begin with this:

Then buy this: AC Delco # 60G Diesel Glow plug. 8.99 at autozone.

Then, get some 3/8 copper tubing from home depot for @ $10:

Drill a 3/8 hole at the bottom of the can and then thread in the glow plug.

Drill out the spray nozzle at the top of the spray can with a 3/8 drill bit. Run a section of copper tube down to the bottom. Once you get it close, bend the copper tube to where the bottom of it is offset to the outer edges of the inside of the can, so that when you later screw the removeable cap on it wont ram the copper tube directly into the glow plug.

Remove the cap with copper tube, take a hammer and smash the last 1/4" to 1/2" of the brass tube to make it virtually air tight. Now, take a very small drill bit, like about the thickness of a paper clip wire. Drill one hole just above the crimped end, so that when you blow air into the copper tube it will be bubbling up thru the baby oil.

Get baby oil! unscented is best, or just get straight mineral oil in the laxative section at your grocery store.

Remove the schrader valve from the valve on the side of the top of the aerosol can. Remove the spring and the schrader valve. now reverse it so and screw it in so the pipe is sticking outwards. Its not the same threads but close enough.

Thats pretty much it. I also used some plumbers putty to seal up the copper tube since I didn't get a perfect fit.

Create a heavy gauge power wire and ground wire with alligator clips at the end to hook up to a battery. Wire up the positive and negative, making sure the positive goes at the end of the glow plug, the negative you can put anywhere on the can just strip the paint off if you do that.

Now add mineral oil to some where like 1/2 way up the glow plug tip or even less than that. Definately don't completely submerge the glow tip or it wont glow too well.

Now I found that this glow plug is a self limiting current kind, so it can take a beating and not instantly blow out and kill itself. I find that if i heat the plug for about 10 seconds, then shake the can a little to splash some oil.

So the copper tube is the air input. Blowing just with your mouth produces about the right pressure to create some pretty good smoke.

I bought some 1/4 clear fish tank vinyl tubing, ten feet long from home depot in the plumbing section and a copper end as my smoke output hose. Plug this onto the output (old schrader valve). Power up the plug, and prepare for the can to get hot. That's usually when I let off the power to the plug.

Plug this into a vacuum port on your intake, like the supply hose to the brake booster or the hose to the vacuum advance.

You'll have to block off the carb top. I found a big permatex hand cleaner "bottle" fits perfectly over the top of the carburetor.

Look for the smoke , and you found your leak!

Oh yea, forgot about the air source:

You can regulate an air spray nozzle down to 1 or 2 psi, fit a rubber hose over the end of the copper tube coming out of the top of the spray can, and fit your barbed air nozzle into the rubber hose.

I've read of other people using a cheap 12 volt emergency air compressor like you get for $10 at kmart. cut off the end of the output hose and just attach this setup to your copper hose. these things dont put out much cfm, but you'll have to experiment and may need a air regulator inline anyway.

Edited by 74elco for73SS on 08-17-09 07:03 PM. Reason for edit: No reason given.

Valued Contributor
Posts: 2714

Reg: 04-15-05
08-17-09 07:27 PM - Post#1755910    
    In response to 74elco for73SS

UNLIT propane works best for me, and thousands of others, and, no loss if vision and view with smoke all over the place.

For those engines that don't have vacuum leaks in the inlet system, one can flow the UNLIT propane down the carb inlet as the engine is running in the rpm range the issue is in, and check it for lean/rick running. Smoke won't let you do that.

Just my opinion.

Edited by IgnitionMan on 08-17-09 07:29 PM. Reason for edit: No reason given.

74elco for73SS 
Senior Member
Posts: 575
74elco for73SS
Loc: so cal
Reg: 04-30-04
08-17-09 07:55 PM - Post#1755931    
    In response to IgnitionMan

i agree, but i worked at a shop before that had an expensive smoke machine. For a flat rater, it by far was faster to pump an intake up with smoke and search for the leak that way, then spraying carb cleaner or using a propane wand. Each tool has its best uses and is better or worse than the next tool depending on the situation. All i know is i dont have $1000 to kill on a smoke machine!

74elco for73SS 
Senior Member
Posts: 575
74elco for73SS
Loc: so cal
Reg: 04-30-04
08-17-09 08:56 PM - Post#1755967    
    In response to 74elco for73SS

Take a look at some of these videos to see some uses of smoke:

Very Senior Member
Posts: 2315
Age: 28
Loc: N 42┬░ 53.290' W71┬░ 34.1...
Reg: 10-23-03
08-18-09 06:13 PM - Post#1756529    
    In response to 74elco for73SS

There are a hundred uses for smoke machines from exhaust leaks, intake leaks, evap leaks, a/c leaks, cooling system leaks etc etc.

One problems in the proffesional world is they dont want you to use shop air when smoking a fuel system or evap system because the air in the shop line would have enough oxygen that an explosion may happen. No one has heard of that happening or seen it for sure, but there are a bunch of warnings in the manual that we have it hooked to nitrogen. But very kool for a cheap alternative!
1982 Chevy K20 Converted from C20.
2002 Yamaha XVS1100CL VStar
2002 S10 2WD

Forum Newbie
Posts: 2

Reg: 12-18-09
12-18-09 04:46 PM - Post#1826463    
    In response to N8sToolz

Here is a much better solution

74elco for73SS 
Senior Member
Posts: 575
74elco for73SS
Loc: so cal
Reg: 04-30-04
12-18-09 07:43 PM - Post#1826563    
    In response to glasses97

Thanks for that- thats awsome. How full of mineral oil do you fill that with? Yours seems to put out more volume of smoke than my setup, which is what you want.

Thanks for signing up here and contributing! Once people hunt a vacuum leak down with smoke they'll never enjoy doing it any other way!

Forum Newbie
Posts: 2

Reg: 12-18-09
12-19-09 02:52 PM - Post#1826986    
    In response to 74elco for73SS

The max fill level would be to just under the wick mounting plate ( about 4 inches of oil)

Forum Newbie
Posts: 1

Reg: 07-28-12
07-28-12 08:02 AM - Post#2252957    
    In response to 74elco for73SS

This looks like a great idea can you send a picture of what it looks like finished ? My addy is Thanks a million .

Forum Newbie
Posts: 1

Reg: 04-29-14
04-29-14 11:09 AM - Post#2448705    
    In response to glasses97

seems you link does not link to the post, is there another way your smoke bucket can be seen? Thanks for you thoughts and posts!

Frequent Contributor
Posts: 2113

Reg: 08-06-08
04-29-14 05:12 PM - Post#2448791    
    In response to N8sToolz

good for turbo plumbing leaks too...

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