Boost leak testing

I've been trying to do a boost leak test this morning, I read through the tech articles but I can't seem to get the system to hold any pressure? i.e my boost gauge never moves.

Am i missing something, I've got the boost leak tester in the intake piping after taking the pod and afm off and when I try to pressurize the system it just doesn't seem to hold any pressure?

Any help would be appreciated

 

How big is the air compressor your using?

 

Big enough I would assume, its a Titan 900 MC-11.

What pressure should i set the regulator to?

 

When I was doing mine I found my compressor connectoin wasn't pushing the valve in on the tester. So I removed the stem from it, set the regulator on the Compressor to 5psi and taped the handle on.

I had that many small leaks that it wasn't registering pressure tester gauge but as I worked them out, the pressure slowly came up and by the end of it, I could remove the tape on the handle and it would hold and slowly bleed down.

 

Well that seems like the same thing thats happening to me, except i know i'm getting pressure into the system. so i guess it's time to hunt for leaks...

 

This is where a smoke tester is good

A normal boost leak tester is very limited in its capabilities, handy for the toolbox but a bit lacking when it comes to the serious stuff.

If you have boost leaks all over the place, the air leaks quicker than you can put it in so no hissing noise is created and you have NO idea where the leaks are located. The smoke tester sends up little white smoke signals everywhere it can escape, making it easy to systematically rectify the leaks one by one.

If you have a tiny leak, the normal tester will not even identify you have a leak but the smoke tester will wave a little white flag.

I don't even get my BLT out of the toolbox anymore, I just shoot straight to the local workshop and use the smoke tester. The time saved more than outweighs the charge for their time.

If it wasn't for the ridiculous price they charge for smoke tester units I would've had one sitting in my garage years ago

 

Also forgot to add, I used a squirt bottle with a little bit of dishwashing liquid in it. Where I suspected a leak was, I'd spray that area and watch for bubbles.

 

I'm digging this thread up again, as I'm still having trouble trying to figure this out.

I've plugged a boost leak tester (home made one as per tech article) into the intake piping where the pod normally is, hooked the compressor up, set the reg on the compressor to about 25psi(?).

I've also plugged a boost gauge into the vac line where i normally have my in car boost gauge connected to and jammed the accel pedal open.

Now here is where my problem is,

When I try to pressurize the system the boost gauge doesn't even budge, not even to 1 psi, from all I've read on the internet about boost leak testing this means that I have a really bad boost leak, The car doesn't drive that bad though, I suspect I might have some boost leaks, but i would think it was THAT bad.

Anyone got any ideas on what I might be doing wrong or what the problem could be?

Also how long should i be trying to pressurize the system for? how long should it take before something registers on the gauge?

Thanks for any help in advance!

p.s pic of what I've got hooked up if it helps, sorry for bad quality just took it with my phone.

 

Too much pressure.....

about 7psi is the recommended pressure for boost leak testing. Too much pressure can damage seals.

When you have boost leaks, the idea is to apply constant pressure to the system enabling you to locate the leaks (listen for hissing). Once you eliminate all leaks, your system will hold pressure for about 30 seconds before slowly bleeding off pressure.

 

The system isnt holding any pressure at all though, thats why i turned the pressure up a bit to see if it would make any difference, I'm not acctually 'pressurizing' the system to 25psi because of the massive leak i have somewhere, so I dont think it would blow any seals till the system was acctually pressurized. Correct me if I'm wrong

I think I'm doing everything right, I just must have a big boost leak somewhere... or lots of small ones?... SO far i have found two vac leaks (vac hoses non existant on nipples!) on the carbon canister and a few leaks around the stainless intake pipes, and its STILL not holding any pressure in the system! I have a feeling this car is going to be a different beast once i get to the bottom of all of these!

 

Im in the same boat. Testing and testing trying to find any leaks. I had a bunch up near the balance tube, to the idle unit, to the clutch booster. The old hoses that were taken off and put back on are very brittle and crack.

Leaks freekin everywhere.

 

Check your dipstick tube. If your PCV valves are stuck then you'll pressurize the crank case and blow out the dipstick.

Also I'm not 100% on valve overlap on the VG as to whether any of the cylinders have both intake and exhaust valves open slightly when off, seeing this will just push air out the exhaust and well, good luck trying to pressurize the atmosphere with an air compressor.

 

PCV`s are brand new

I do not understand what you mean with good luck trying to pressurize the atmosphere? The intake atmosphere? An area about the same about 1 or 2 car tyres. No problem. The intake system.

And yes, air will slowly leak out the exhaust, but very slowly. Slower than that of a prominent leak.

 

Slow process.....

25psi will not harm anything while you have massive boost leaks, but as you eliminate each leak the system will start to pressurise.

Start by checking for any loose or missing hoses, it's awfully hard to hear a leak if you have a 1cm hose disconnected. It would be like pissing up George Street

Once you ensure no hoses are disconnected, you should be able to hear the leaks (yes, you can hear 7psi escaping). Unless the system will hold pressure (as described earlier) you still have leaks, so keep searching.

Sooner or later you will eliminate ALL the boost leaks. If you don't have the patience to complete a boost leak test then I suggest you sell the zed, because long term ownership of a zed needs a copious supply of..... TIME, PATIENCE & MONEY

 

Before the zed I rebuilt an '85 930 porsche Turbo. Long story short due the way we built the engine, we had significant amounts of overlap on the valves. So when the motor was off, cylinder 3's valves were both open, and hence a pressure test of the intake required the exhaust to be plugged. So when I said atmosphere...i was just using humour, cause you can't pressurise the intake in those circumstances. Anyway, obviously not enough overlap in a stock cam'd VGTT so ignore my comments.

 

Yes well I think thats my problem, a vac hose somewhere is missing or off. I found 3 so far, after spending probably 5 hours searching, its a hard task when you can't even pressurise the system, so your trying to keep the compressor pumping air into the system (i zip tied it onto the intake pipeing lol) then try listening for leaks, its VERY hard to work out what is just air running though the intake pipes (like it should) or what is air escaping!

I would imagine its a lot easier to find the leaks when you can pressureize the system then stop the compressor and just listen for any air escaping, but at this stage I can't pressureize is.

p.s Telling me to sell the zed is a little un-called for i think... At least I'm trying, I was just trying to get some help from more experienced people or to see if what I was doing was wrong... :lame:

 

I didn't tell you to sell the zed....

I was offering the advice, that if the frustration of looking for a boost leak is going to test your patience then maybe a zed is not for you. These cars can be an absolute PITA and it's not as if you can just pay someone to fix them, because in the majority of cases "we" know more about them than most workshops I don't think there'd be a single "long time member" on this forum that hasn't been tempted to reach for the box of matches on more than one occasion

The only time that maintaining a zed is not frustrating is when you've finally replaced or rebuilt everything under the bonnet :bash:

 

I'll put my hand up for that.

*and no...i did not burn my own car*

Don't be discouraged mate, the lure of a zed a low cost-high performance car is tempting, but at the end of the day, it's an enthusiast car. Either those who enjoy doing the troubleshooting and work on their own, or who is happy to pay someone to do it. If it ever gets too much just chill abit shoot a querie out to the forum and baby steps. At the end of the day, it's the same as any engine, just more tightly packed in with a whole lot of weird and wonderful (often unnecessary) bits hanging off it. Collectively you have the resources to attempt any piece of work on the zed if you have the time and patience.