DIY - Vac Leak Test - Find Vacuum Leaks

[theswoleguy]

I posted this in the Golf/Jetta Forum as well bc some of them dont venture to the 1.8T side of things. So hopefully this may help some of you.

Well basically I have been having troubles with the dub... Back n forth to dealers, various people checking it out, all in all erratic idles, and occasional lean codes. Well we all know most likely a vac leak. So i finally got tired of it and figured out a way to go about and attempt to solve my problems. I tried everything i knew n heard of about vac leaks from fogging with a flammable substance to just oldschool grab n wiggle. Well this is what i came up with. For a more permant solution go to HD or Lowes and get 2.5 Conduit pipe and find a PVC pipe cap that will slide in and pipe glue it together) Also i recommend not pressurizing the MAF like i did just go around it, remove it and go on the TIP.

I have since changed the below requirements to a PVC pipe and plug cap for a more suitable solution. I have made three sizes, 1.8t, TT/VR6 and one for my Truck

Materials:
1 Drill
2 Drill Bits (1 as pilot hole, 2nd size of Air Fitting)
1 dogfood or soup can (clean and roughly the size of the MAF)
1 Transition coupler (Most of us have intakes so there you go)
1 Air hose fitting
1 Nut to thread on Air hose fitting
2 rubber washers
3" Thread tape
1 Air compressor / Bike pump
X feet of Air line to reach from pump to MAF

Directions

1. Take the can and drill a hole in it on the bottom. Now take and smooth the rough edges flat, wash the can to dispose of any left over shavings (becareful can might be sharp)

2.Now place rubber washer on air fitting, thread tape the fitting and screw it into the bottom of the can. Take the nut and the other rubber. Place the rubber washer on the inside of the can on the Air Fitting Threads. Now tighten down.

3. Now place the transition coupler over the can, tighten hose clamp. Now take the can w/ coupler and attach to the MAF or if you removed the MAF (recommended) Place it in the TIP and Tighten clamp.

4. Most Aircompressors have two guages. One for the Tank pressure and the other for line pressure.

5.Turn the line pressure down to zero if the tank is already full. If its empty turn it all the way down and go ahead and start charging the compressor.

6.Now attach air hose to the can with the fitting. By now your tank should have some air in it. Turn it to about 10-15psi (Most AC gauges go about 15lbs as their lowest reading, so by now hopefully you have a Boost Gauge in car) go check your gauge. At about 10-15lbs you should hear your leaks i heard mine at 10.

7. Find/Found Vac Leaks Decompress, fix problem, Refill fix other problems if you have more then one leak, decompress and fill again till no leaks are found... PLEASE make sure you decompress before you attempt to fix a line or you could poke your eye out kid... This is what i came up with.

Well i hope this helps atleast a little. At 20lbs the PCV tends to blow oil into the intake and the oil cap tends to leak air also so try not to go that high... Im sure there is a way to cap the PCV side so not to recirc some oil (As if the car was running) back into the intake runner. As it does for emmision purposes. My car idles awesome again, starts great now, runs great, boost excellant, and pulls 19" of vac at idle and 21 on decel now.

Also as always: I nor VWVortex take any responsibilities for injuries to yourself, dub, or bystands wondering why the **** your giving your car a *******.

Modified by theswoleguy at 9:33 AM 11-22-2006

[djpj06]

great set up. looks a lot like the vag tool. the vag tool comes with a plug that you install into the intake boot in place of the pvc....so no gurgling

[GiacGti]

its nice to see people do productive things.

[TurboZen]

Quote, originally posted by djpj06 »

great set up. looks a lot like the vag tool. the vag tool comes with a plug that you install into the intake boot in place of the pvc....so no gurgling

can use a hose clamp as well to stop it from leaking. good pics.

[Boostin20v]

Added to FAQ's in the DYI section

[JacksSmirkingRevenge]

May I suggest adding Chris' as well.

pressure testing your intake

[beachball6]

wanna take a road trip to tx? ill let you do further testing on my car.

[Smokey the Bandit]

egh, I need to pressure test my setup once its all back together, but damn, just got rid of all the intake piping, and slap'd a k&n right on the turbo.... looks like its goin back on. good write up though

[transient_analysis]

people keep calling this type of test a "vac test", but when in reality it's a "pressure test"

Does anyone know how to actually do a "vac test"? Is there anything that would be found by a vac test that wouldn't be found by a pressure test?

Funny true story (and related)..

A trucker chick (yes.. chick) stoped at friends lumberyard early one morning to drop off a load of wood. After scaring off the yard guys with her foul odors, she went to her cab, pulled a can of cat food from the floor and preceded to eat the thing with a plastic spoon..

That's one way to clean the inside of a can for this project

[theswoleguy]

Quote, originally posted by transient_analysis »

people keep calling this type of test a "vac test", but when in reality it's a "pressure test" Does anyone know how to actually do a "vac test"? Is there anything that would be found by a vac test that wouldn't be found by a pressure test? Funny true story (and related).. A trucker chick (yes.. chick) stoped at friends lumberyard early one morning to drop off a load of wood. After scaring off the yard guys with her foul odors, she went to her cab, pulled a can of cat food from the floor and preceded to eat the thing with a plastic spoon.. That's one way to clean the inside of a can for this project

im sure if you have a vac leak this pressure test will find it, doin the same thing just with boost, some vac leaks seal under decel, and off set by boost, thus is why its usually really noticable at idle where its more ambient pressure and the hole(s) opens up. O yea and quiet disgusting. lol i say just wash it out lol


Modified by theswoleguy at 8:29 PM 7-3-2006

[krzys84]

im going to have to do this soon.

[briang]

Ingenious! This post should be a sticky.

[rep ny]

Quote, originally posted by JacksSmirkingRevenge »

May I suggest adding Chris' as well. pressure testing your intake

i used this method and it works great also

[MightyDSM]

Quote, originally posted by rep ny »

i used this method and it works great also

Great write up
Just to add some info, when I did the boost leak test on my DSM some time ago, I used a piece of pvc pipe and put a valve from a tire on top and sealed it with JB Weld. I like the idea with can too, would never think of it

A question thou, are you sure it's a good thing to pump it up to 15 psi?

[GTI MK4]

great write up i will try that out but on another note i was wondering if you could send me a list of your upgrades i like the idea that your still useing a ko3 and geting that much whp and im sick of being wasted by sti's and evo's it seems like every new sports car has more then 250 hp even the new cobalt ss so 200 whp just aint going to cut it any more so if you have a chance hit me back i could use another 60 horses and i would like to have a set up that has been tried and tested

thanks

[theswoleguy]

stis and evos will still be hard to press on, i crept on a newer body sti about two weeks ago, license plate V8Killa. There still fast. I will be going big turbo this was just buyin time.

**My turbo is well ragged out well beyond past its efficiency.

With that disclaimer ill tell you all you want to know

[the brit]

This thread was recommended to me by a VW Tech Looks like i'll be trying this is a few days.

[ColoradoSoul03]

The way to cap the PCV system so you don't blow air into the crankcase is to pull the little black check valve out of the TIP and plug it with something, just leave the valve aside. This is the only place (unless you have leaking rings, valve guides, etc.) that pressure will go into the crankcase.

[stevemannn]

you do realize this is from 2006
and its in the faq right?

[1.8Tjettta01]

U should make these dog cans and ship them lol....

make some money off of them!

sounds good

[ockey53]

watched, great write up!

[yasuep]

Thanks for the great DIY. I managed to copy the idea with some junk I had lying about. Put about 3~5 psi on the intake. Immediately heard a large leak, and started to search. Oddly, it was the cam shaft plug (rubber) in the end of the cam cover that was missing. The air was rushing out from the hole. Would a missing cam cover plug cause several CEL, such as 17705 or 17545 ? I also experienced the occassional difficulty in getting the SAI readiness to set.

EP

[brookrock]

nice job

[interceptorvfr]

You guys please help i did this yesterday and when i started the car it was smoking like crazy (oil) after driving for a while it has slowed down alot but still smells like oil burning and slightly smoking.....please help.....i only went to 12psi on the comp....04 jetta gli

[zeusenergy]

Quote, originally posted by interceptorvfr »

You guys please help i did this yesterday and when i started the car it was smoking like crazy (oil) after driving for a while it has slowed down alot but still smells like oil burning and slightly smoking.....please help.....i only went to 12psi on the comp....04 jetta gli

You pressurized the PCV system and oiled the inside of your intake manifold as a result. The black round piece near your DV (PRV or UFO or hockeypuck) will let air into the PCV lines, then from there it will go into the block, head, and of course the PCV valve itself and into the intake manifold. The oil will clear out- but you can retest with the hose pinched or just cap it off.
And this thread is older than my grandmother's pet dinosaur.

[interceptorvfr]

But how long will this take to clear out i mean i drove it like 45 miles and its still smoking.... and the worst part is that i didnt even find a vac leak and my car still runs like garbage

[zeusenergy]

Well figure all the crap inside the hoses and the hockeypuck went into the intake valves and coated the manifold.... and prolly got all over the O2 sensors too.

[interceptorvfr]

awesome thats perfect haha well i guess i will just take the exhaust off and clean it out...what do you think about spraying carb cleaner or starter fluid into manifold

[zeusenergy]

Don't bother with either. If it still smokes after 100 miles more you might need hoses, a new PCV and/or PRV. Or just do a catch can and save half that money.

[theswoleguy]

Quote, originally posted by zeusenergy »

Don't bother with either. If it still smokes after 100 miles more you might need hoses, a new PCV and/or PRV. Or just do a catch can and save half that money.

x2 usually smokes for a few minutes and clears, after i figured out what it was i just started plugging it, but i also have a CC

Quote, originally posted by zeusenergy »

And this thread is older than my grandmother's pet dinosaur.

and wow almost 3 years.

[Nevaeh_Speed]

A+ diy

[aadosx]

Ok well I just tried this and have some questions.

First of all, it took me a few trips to some hardware stores to get the stuff.. there wasn't a nut that fit on the air compressor fitting in the hardware isle.. I ended up having to find some weird hose fittings.

Also while doing it.. the thing did pop off once and scared the sh*t out of me! It flew right past my face too.. man I'm lucky.

Anyways, I've found a few leaks so far: where the brake booster connects to the side of the intake manifold; a cap I have on an intake manifold port, under the intake mani, that some old PCV stuff was originally connected to; the FPR line is leaking at the FPR; and also a small hose branching off of the TIP was leaking.

Now that I have all of those fixed though.. I am still hearing a lot of noise coming from behind the engine, near the turbo... but I cannot find/feel a leak to save my life! Is it possible that it's just air running through all of those lines back there?

Another thing: Whenever I would pressurize my system, i would hear a gulping noise (gulp gulp gulp gulp) coming from in the engine. WTF is that??

Thanks!
John

P.S. Two of my leaks were due to some vacuum system caps that I bought from auto-zone or the like that had just dry rotted. These things are less than a year old.. why do they rot out so fast? I don't want to have to replace them constantly just to not have leaks.. any suggestions?

[theswoleguy]

the gulping is air going into the PCV system, its ok, will cause some smoking. the other area you hear check with soapy water around the tip theres a hose that plugs on that leaks sometimes too

[aadosx]

Hrmm well I plugged the port on the TIP that the PCV system connects too.. I thought that was supposed to prevent that from happening? I didn't have an unusual amount of smoke either.

[Ld7w_VR]

Not the first time seeing this DIY but now I am making one of these to find this dam vacume leak. Great idea