Smoke Testing Cooling Systems

[00scrub]

I am trying to pressure test the cooling system on a Porsche GT3 engine on the bench. I am able to pressurize the system with air, but get a slow leak of ~1psi every 20mins. I'm trying to track this down and soapy water isn't doing anything.
Is it safe to use a smoke machine like you would use to find a vacuum leak in the cooling system? Will I end up with a coating of soot/mineral oil inside the cooling system?
Thanks

 

[50yr Street Mech]

I'm no expert, but if you're losing air, it's leaving. So, I wouldn't think it would suck it in if the air is escaping. Think of it as being a tire, the air is leaving, but you just can't find it with soapy water.

 

[00scrub]

I was thinking of stuffing the smoke output into the port I'm using to pressurize the system so I could fill all the cooling passages with smoke.

 

[Snagglefoot]

I don’t think you’ll find soot, but there’s a minute amount of baby oil that might be deposited. I imagine you would want the spark plugs out so if it enters the combustion chamber of would come out the spark plug hole. Not sure if it would condense the smoke too quickly to see.

Here is my Ancel smoke detector. It came with a soft rubber cone which you can stuff in the radiator opening or coolant tank. The rubber hose is attached to the inside end of the cone. In my picture I’m smoke testing an exhaust system. Also shown is the smoke coming out of the hose at 2.5 liters per minute with no back pressure. It vaporizes Johnson baby oil. No jokes please.

 

[clinebarger]

Do it regularly with my smoke machine if the system won't take a vacuum.

 

[wlk]

I am trying to pressure test the cooling system on a Porsche GT3 engine on the bench. I am able to pressurize the system with air, but get a slow leak of ~1psi every 20mins. I'm trying to track this down and soapy water isn't doing anything.
Is it safe to use a smoke machine like you would use to find a vacuum leak in the cooling system? Will I end up with a coating of soot/mineral oil inside the cooling system?
Thanks

Sounds like a good idea but are you sure it isn't just the schraeder valves? Most of the leaks I have ever had were those. Even with new ones, I have seen them leak. I'd swap them again and see if it doesn't help. Good luck tracking the leak.
Sorry, if cooling as in hvac or engine cooling system? If engine, discard the above and yes id smoke it and not worry about it

 

[KrisZ]

Of course you can use smoke to test for leaks, why would that be a problem?

 

[00scrub]

I'll check the schrader valve. I don't know why i didn't try swapping that already. I didn't see any obvious leaks with soap on it when sprayed, but it might still be getting out there.
KrisZ, I was worried about smoke leaving residue in the cooling system.

 

[KrisZ]

KrisZ, I was worried about smoke leaving residue in the cooling system.

You're way overthinking this, and unless you used an old diesel exhaust as you're smoke generator, whatever residue a normal smoke machine might leave will be harmless. The cooling passages can have sand residue from the casting process in them. I've seen it myself on the first coolant flush. You have nothing to worry about.

 

[Snagglefoot]

Out of curiosity are we talking about an AC system or a radiator cooling system.

 

[00scrub]

KrisZ, good to know it isn't much of an issue.

Snagglefoot, this is for the radiator system. I had half a mind to borrow a Helium leak tester from some HVAC folks I know though.