Pressure test smic

[SamHendry]

Hi i want to identify any leaks in the smic on my s3 using a compressor. Smoke test isn't an option. Does the throttle body stay air tight? Is there a particular fitting anyone can recommend or suggestions on some type of plug/valve I can put together myself?

 

[VAG-Slag]

Why isn't smoke test an option? . . No, the throttle body does not stay air tight. However most smoke machines should come with various size bungs to plug up the TB pipe if needs be..... If not, improvise I suppose!?

 

[aragorn]

it doesnt matter that the throttle body isnt airtight, just pump up and search for leaks.

the pressure will slowly seep away, but thats not really an issue, you have plenty of time to discover leaks.

A useful trick is to shut the compressor off at the mains so the pump doesnt run, making it much easier to hear any hissing when you pressurise it.

Connect the compressor in place of the MAF, and make sure you disconnect and bung the PCV fitting so you dont pressurise the crankcase.

 

[SamHendry]

Yeah plug PVC and test. Would pressurising the complete system do any harm? My thinking is could possibly attach some type of shrader valve to a 80mm cap of some description. Smoke test would be the preferred method but no one local.

 

[A3-Lee]

Where are you based?

 

[SamHendry]

The great scottish highlands

 

[VAG-Slag]

Pressurising the whole system wont do any harm. but would confuse results as you'd get smoke coming out of all sorts of places!

Scottish highlands ey? . . You literally weren't joking when you said "no one local" then? Like literally, NO ONE! lol

 

[aragorn]

Why would you get smoke coming out of "all sorts of places"?

Its a sealed system, if smokes coming out then somethings broken.

You dont need smoke anyway, a compressor, some sort of fitting to go in the end of the intake pipe and your ears is all you need.

 

[VAG-Slag]

From personal experience, if you don't plug up the breather, you'll get smoke coming out of places like the dipstick and oil cap etc... And as said, it just confuses things!

And I beg to differ, you won't hear all leaks... That's why proper smoke fluid leaves a trace only detectable by UV light

 

[<tuffty/>]

Using high pressure from the TIP could cause a pressure build up in the crankcase which may pop seals out in extreme cases... this is why smoke testers use 1/2psi of pressure as its generally enough to find most leaks...

Its not infallible as higher boost pressures can move things enough that stuff may only leak with a degree of pressure applied... this can be the case for intercoolers and I do know of a time where a smoke test failed to pick up a faulty intercooler that would only leak around the crimped end tank when it saw actual boost pressure...

Applying pressure to the whole system will leak through into the engine and out the PCV... often have to clamp PCV pipes on cars with catch cans etc if they vent to atmosphere and often see leaks from dipsticks and seals in the head (half moon under cam chain tensioner is a classic)

<tuffty/>

 

[aragorn]

Well the point is the crankcase should be open vented anyway, you shouldnt be sealing it in such a way that pressure can build up in there when your doing a proper pressure test. Seal the fitting into the TIP and leave the pancake valve open to atmosphere. probably also worth taking the oil cap off too.

With enough pressure you'll hear leaks just fine. At 5psi the o-ring on my temp sensor doesnt leak at all. At 20psi it makes a nice audiable hiss.

If its leaking enough to discharge smoke at 1-2psi, it will be making plenty of noise at 10-20psi.

 

[SamHendry]

Pressurising the whole system wont do any harm. but would confuse results as you'd get smoke coming out of all sorts of places!

Scottish highlands ey? . . You literally weren't joking when you said "no one local" then? Like literally, NO ONE! lol

HaHa I'm deadly serious mate. I think I might be the most isolated s3 owner in the uk.

Aragon tuffty thanks for the input. I will report back with what I decided to do!