Feckin Pressure Testing

[Dr H]

Tested my car for leaks again today and I can't get it to pressurise above about 6psi I'm using Grahams pressure tester connected to an electric tyre pump. I've blocked off the cranckase ventilation pipe and the hose just before it goes into the big metal pressure pipe along the side on the valve cover.

When you stop the pump it immediately starts to loose pressure and has lost it all in about 3 seconds. But as the pressre is so low you can't hear it escaping. Do I need to block anyting else? Surely the pressure should get higher than this as I can get it up to 1.5 bar on the boost guage before it then starts to loose pressure.

Any suggestions gratefully received.

[Glen Chamberlain]

I have used my own pressure tester on the MAF pipe like Grahams with not much success really! I found the best way is to pressuer only the BOOSTED pipes like the turbo does! Not really that easy but i did it with a reducer on the air line @ work. I took the pipe from the Turbo and blocked it with an air pressure switch from a coach. Blocked the Throttle body pipe with an oil can or areosol can then pressureised the system through the ISCV pipe with a 1/2 drive 8mm scocket as a reducer to slide some piping over. This i found to be the most reliable method of testing the big pipes but you cant test the turbo to ic pipe connection cos its already disconected!

With my original dump valve it didnt leak when tested this way but with the new (OE) one on it did? (slightly) Just put it down to the DV needing the same boost pressure on the vac pipe to keep the valve on its seat?

[Graham]

The small amount of sepage through the valves might be just enough to counteract the small displacement tyre compressor, mine held pressure for quite a while, and i found it easiest to run it off a garage comrpessor with a pressure reducing valve through the 1/2"bsp fitting. If you know someone with a garage, get them to test it, or borrow their air.
Graham

[Graham]

Also i think this week i will make a bung for the rubber section before it goes in to the manifold, this should eliminate all escape paths for the air, leaving only leaks to blow.
Graham

[Dr H]

Originally posted by Graham
The small amount of sepage through the valves might be just enough to counteract the small displacement tyre compressor, mine held pressure for quite a while, and i found it easiest to run it off a garage comrpessor with a pressure reducing valve through the 1/2"bsp fitting. If you know someone with a garage, get them to test it, or borrow their air.
Graham

By valves do you mean tbv and wgfv? I blocked off the pipe before it reaches the manifold thefore the engine valves don't come into it.

Leigh

[audiman]

pressurise the hoses after the turbo. ie the hose from turbo to the intercooler.

[S2central.net]

Leigh - you also need to disconnect and bung the hose from WGFV to WG. Leakage past the WG is normal, but it hurts my head to understand why that is so. WGFV is also normally leaky in the 'closed' position...

Try pressurising just the 8mm hose into your wastegate and see how much pressure it holds - gives me a sore head as Mihnea says its normal !

Cheers,

Paul

[Dr H]

Cheers chaps - when it stops raining I'll give it a go!