Help Boost/vac leak continued.... (starting to make progress)

[BlackMetal]

I've had my homemade leak detector ready for a few days but just got a hold of an air compressor today.

Right off the bat found an obvious leak on one of the lines where I T'd into for boost gauge. Had some little plastic vacuum port caps laying around so I removed the related lines off of the vacuum block and capped them off. So that leak is out of the equation.

Still when I pressurize the system with 20 psi it bleeds off within 10 seconds. I have the rocker shafts loosened so no valves are open. Also I have my leak tester installed right at the throttle body, so various intake and intercooler pipes are not even in the equation right now.

I'm guessing this still isn't acceptable, correct? Theoretically with the valves closed and only pressurizing to 20psi, I should literally have no bleed-off? I also hear some "whining" from inside the car while pressurizing (driver's window open) but I think I'm just hearing the boost gauge working.

Appreciate any help, happy to finally be getting somewhere with this.

I think I hear something from the rear of the intake but right now I'm working alone so I have to pump up the intake and then quickly position myself to try to feel around for leaks.

 

[Junior Samples]

Are you using any kind of smoke? do you have regulator or are ya turning on comp...shutting off then running over to get 10 sec worth of troubleshooting?

Simple smoky leak detector

 

[sykegn]

i am pretty sure there are a few vacuum lines under the dash for the heat and ac.

 

[BlackMetal]

Are you using any kind of smoke? do you have regulator or are ya turning on comp...shutting off then running over to get 10 sec worth of troubleshooting?

No I don't have any kind of smoke handy right now. And I didn't use a quick connect hose fitting on my tester, it's a tire valve, so yeah I have to inflate first then drop the hose and quickly try to diagnose. At the very least I will get a 2nd person to help me tonight, they can keep the air pumping while I feel around.

i am pretty sure there are a few vacuum lines under the dash for the heat and ac.

Yeah at this point I blocked off the entire vacuum block so any lines relating to the heating system, EVAP system, etc, are all blocked right now. And I'm still getting the same result. So it's definitely something related to the engine itself, gaskets, whatever.



Anyways I just wanted to confirm that the air still shouldn't be leaking out like that, not that I was overlooking something where the air was escaping that wasn't actually a leak.

 

[BlackMetal]

Well I was able to have someone help me just now and got pretty discouraged that I still can't feel a leak anywhere. I know I'd be better off using smoke to help locate it but don't have money to spend right now rigging up something for that. Did notice little bit of a leak from my homemade boost tester just not sealing well in the silicone hose but I don't think that's the total blame, this 20+psi of air that I'm injecting disipates within seconds, almost like what I would expect had I NOT gone through the trouble to make sure the intake valves were all closed. This isn't behaving like a puny little leak it's more like it's rushing out through a 2 inch hole. The car doesn't run badly enough to actually expect a messed up valve or anything. I really don't feel like doing the intake gasket on a guess even though at this stage of disassembly it wouldn't be that much more work to pull the intake.

This is why all along I was hoping I could locate an actual smoke machine because there's no guesswork involved when you see the smoke streaming out somewhere.

And again to summarize:
-vacuum lines are completely out of the equation
-boost tester is installed at throttle body, so there are no intercooler or intake pipes involved
-rocker arms are loose to allow intake valves to shut

So we are talking about a small area here, all I'm testing is from the opening of the throttle body, through the plenum, down through the intake runners and should be stopping at the closed intake valves. Somewhere this 20psi of air is finding a way to escape and I can't detect it.

 

[sykegn]

how about your egr valve?

 

[charlief1]

Go to the parts store and either get a stethiscope or at least a peice of hose about 3-4 feet long and stick it in your ear so you can hear the leak. Move it around the engine and see if you hear it.

 

[BlackMetal]

how about your egr valve?

EGR valve is removed and I have a plate from FullThrottle over the old EGR port and sealed with copper RTV. I made sure to check in that area for a potential leak but it appears to be sealed.

Go to the parts store and either get a stethiscope or at least a peice of hose about 3-4 feet long and stick it in your ear so you can hear the leak. Move it around the engine and see if you hear it.

Yeah I've heard of that trick before I guess I can give it a try. 12 gallon air compressor kicks on every few minutes so diagnosing by listening gets to be a pain in the ass when I can't hear anything in the garage.

 

[charlief1]

Use a longer feed to keep the noise away.

 

[WSLN 6]

You could also idle the car and take one of the vacuum hoses off and dip it into a small container of ATF. Just a 1/2 second should do the trick. Look for white smoke.....

 

[turbo nasty]

If you are hearing it in the car then I bet the HVac 3 way check valve is shot and your psi'ing the hvac head unit inside.
3 check valves...
1. one by fuel vapo canister
2. hvac 3 way at back of engine by firewall( engine, hvac, vac canister/cruise)
3. one pre egr
Check them out as they go out2 of mine were shot.
If you have a alum vac block on top of the TB spray that sucker with soap bubbles and see if its leaking. All of mine had no sealant onthe threads and everyone was blowing air . I resealed them with permatex # 2.

I also had to pull the intake and replace the gasket as 3 ports were seeping. it was just old . Also my egr stem was leaking around the stem.

FWIW I tried propane, carbcleaner, brake clean, etc etc at idle and spray and sprayed and the idle never would change even though I had alot o leaks. Only way I found these items was doing what you are

 

[1KWIKSIX]

Instant smoke

I found a real nice easy to use set up that produces instant smoke and it worked out great for me when I was chasing down leaks.

Zero Draft Air Leakage Detector....used by HVAC industry by people who check for drafts in your home for energy conservation.

Try www.zerodraft.com

Good Luck !


dave

 

[BlackMetal]

If you are hearing it in the car then I bet the HVac 3 way check valve is shot and your psi'ing the hvac head unit inside.
3 check valves...

I also had to pull the intake and replace the gasket as 3 ports were seeping. it was just old . Also my egr stem was leaking around the stem.

I've had the vacuum hose for the HVAC capped off for a long time now as I thought that was a good chance that's where the leak would be. So that line is out of the question as far as the testing I'm doing right now. I went ahead and blocked off the entire vacuum block so none of the lines are even involved right now.

Sorry for the poor photo but this is what I came across today. Using soap since I don't have smoke handy.

Should I just try tightening the intake bolts or is this a serious enough leak to replace the gasket. Didn't see any other intake leaks except right here. And yeah that vacuum block was bubbling even though I put a blank gasket under it to completely block it off.

 

[charlief1]

Told ya it sounded like an intake gasket. I'd take it off and replace it jsut to be sure. The intake may not have been torqued right by the last person working on it.

 

[BlackMetal]

Yeah I will probably take care of it tomorrow, already have so many parts out of the way I might as well deal with it right now.

 

[yullose]

The only part of the intake tract that isn't mechanically sealed with a gasket is the valve guides. The valve seals are to minimize oil to the guides, not intended to be a vacuum tight seal. That will certainly leak down if pressurized... and I sure wouldn't lose too much sleep over it.

 

[BlackMetal]

The only part of the intake tract that isn't mechanically sealed with a gasket is the valve guides. The valve seals are to minimize oil to the guides, not intended to be a vacuum tight seal. That will certainly leak down if pressurized... and I sure wouldn't lose too much sleep over it.

Thanks for the input, that's what I've been wanting to here all along -- whether or not I should have absolutely ZERO air loss, or if the pressure bleeding off was normal (aside from the leaks I did find). Knowing that the intake is not 100% sealed is good info.

Intake was bolted back on yesterday evening. Still need to hook up all the wiring and hoses that I undid.

Doing a few other things to the car now so still can't run it, but hopefully soon I'll be able to fire it up and I better see that damn vacuum gauge at a better reading.

 

[yullose]

Don't forget that ignition timing and fueling will affect vacuum too...

If you changed chips, timing, or lost chip settings over the winter with a dead battery, that might change vac readings too. Even a bad injector will change idle quality and vacuum readings.

 

[Speed_Dreamin']

BlackMetal -

Wondering what your symptoms were before starting this exercise and if fixing the leaks you found helped out? I have been fighting a serious boost spike issue for some time now, have tried multiple things to fix the problem without success. I'm thinking the only logical remaining explanation is a leak in the air intake system. Wondering if you had simliar symptoms.

My car idles smooth, boost comes on quick, I don't have vacuum on my boost gauge, so I don't know what the vac. is at idle. I do hear a tick at idle, don't know if it's an exhaust leak, vacuum leak, injector tick, lifter, valve spring, etc.

 

[Pronto]

Glad this thread came back around. Anyone try a bee smoker? I was watching a show a while ago and saw one and thought that might just work for a leak detector.