Pressure testing without a compressor

[Blue_Thunder]

Looks like the S4 could have another boost leak.

I've got my own pressure tester, but no compressor, so it means I have to either go to a garage forecourt (which are usually too noisy for you to hear small leaks) or head to somewhere like a Kwik-**** who aren't always willing to let you play with their equipment.

I've got a decent tyre compressor, but even though it claims to be able to inflate a tyre from empty in x minutes, it just doesn't seem to have enough puff to fill up the intake of an S4!

I've heard of people using their spare tyre to fill the intake. Sounds like a genius plan. If I did the initial pressurisation of the intake with that method (I assume you'd want to pump up the spare tyre to a failry high pressure first), I could then use my tyre compressor to keep it 'topped up' whilst hunting for leaks.

Can anyone think where I could get an air hose with a schrader valve on each end nice and cheap? Ideally the hose would be long enough to go from the spare wheel well to the engine bay to save faffing about.

 

[NHN]

Why not just get a 12v compressor from halfords etc, as I did to test my charge air system, it goes up to a fair pressure mate & I paid 15 euros over in italy at a diy store, which is sod all tbh & I mate my own kit with a tyre valve & plastic wheel with hole through & stuck valve in hole & sealant round, works a treat.

 

[jcb]

any decent hardware shop should sell pressure tested hose.
try your nearest calor gas shop, not cheap though.

A compressor from halfords may be cheaper!

 

[Blue_Thunder]

That's effectively what i've already got. A 12v Michelin tyre compressor. It just can't flow enough to pressurise the voluminous intake of the S4 due to the pressure which escapes out of the PCV/passed the rings.

 

[NHN]

Are you doing just a charge air system pressure test as surely & correct if I'm wrong but you should be disconnecting at the intake manifold & blocking of to see if from airbox, through turbo, turbo out to IC & then to intake mani where blocked if there's any signs of air escaping, its more than man enough for this test, obviously f I missed something then fair enough, but thats most the boost system no?

 

[Matt82]

this will be no help, but i was planning to use a 12v compressor

how did you actualyl make up a pressure tester though?

 

[Blue_Thunder]

I bought a pressure tester off a seller on eBay who sells them from time to time.

Just looked at a website 12v inflator comparison and there are two Michelin units which look identical. One inflates well faster than the other, so I might just have the naff one (trying to find which one mine is).

@NHN - You wouldn't want to block off the manifold as you are wanting to ensure pressure is held by the injector seals, one-way valves attached to the intake manifold, etc.

 

[jcb]

it shouldn't have a problem filling and pressurising unless there is a whacking great hole somehwere.
The pressure shouldn't escape faster than a compressor can fill it even a 12v thing.

you sure it is pumping?

 

[aragorn]

You should definately be blocking off the PCV connection on the corner of the Y pipe!

The guy that sells them on ebay includes a bung for just that purpose.

 

[NHN]

I bought a pressure tester off a seller on eBay who sells them from time to time.

Just looked at a website 12v inflator comparison and there are two Michelin units which look identical. One inflates well faster than the other, so I might just have the naff one (trying to find which one mine is).

@NHN - You wouldn't want to block off the manifold as you are wanting to ensure pressure is held by the injector seals, one-way valves attached to the intake manifold, etc.

Yeah see your point, depends how far along you wanted to test, but still even with my made up kit it will work a treat with a fulll test with intake mani in place, as the compressor has gauge on anyway you can see if its dropping.

it shouldn't have a problem filling and pressurising unless there is a whacking great hole somehwere.
The pressure shouldn't escape faster than a compressor can fill it even a 12v thing.

you sure it is pumping?

I'd have to agree, these pumps are rated at fair pressure, well mine is, so should be more than man enough

 

[Matt82]

this ebay seller, anyone got a link to one of his sales so i can contact him?

 

[aragorn]

http://cgi.ebay.co.uk/AUDI-S4-RS4-T...arts_Vehicles_CarParts_SM?hash=item25577d9e4e

 

[Blue_Thunder]

millie1507 was the eBay seller.

Absolutely certain my compressor was working as it did pressurise the intake a little bit. Last time I tried it I gave up after over 5 minutes of constant pumping (think it was reading <5psi). When I hooked it up to a proper compressor a few days later the car was absolutely airtight, so it must have been the compressor.

@Aragorn - the PCV breather still vents pressure from the crankcase when you do a pressure test properly.

 

[hardhitter]

You need a compressor with a big enough CFM to fill the air system so you can check for leaks. I'm pretty sure those tyre inflator type compressors are no good since they only pump a small amount of air (your only filling up a tyre, remember). Would have thought you need at least a 25 litre tank/reciever compressor with at least 1 hp.

Did the leak tester come with any requirements for a compressor ?

 

[andybnwc]

i tried a halfords one and it just didnt work just too slow

 

[NHN]

Althought it may take a while to fill up, it works for me fine.

 

[Blue_Thunder]

The intake of the S4 is far bigger than that of the 1.8T.

Not only have you effectively got twice as much pipework, but twice the volume of intercoolers and the pipe routing on the S4 is daft anyway as the pipes go the length of the block 3 times.

This is the whole reason I'm thinking that if I get a spare tyre inflated up to say 40psi, it should be fairly easy to pressurise the intake of an S4 up to 10psi. I can't imagine the S4 intake is more than 4x the volume of a tyre (although I may be wrong).

 

[NHN]

I have a 2.0 TDI mate, but yeah can see your point

Personally if the kit is easy to fit in minutes I'd take it to the local garage & use the air line there, thats gotta be plenty enough to test, unless you wanna get underneath to search for leaks or get a compressor from local store as do find some small ones in diy stores plenty big enough for this, test it & take it back saying to big or small for the job, completely law abiding & cost just a journey to/from