# Question about leaks; what's considered "normal" leakdown?



## FlybyGLI (Jun 20, 2008)

First I would like to clarify that I am not new to air ride and am no slouch in terms of common technical knowledge. I also did a little searching as some of you may suggest, and most threads about leaks involve a bad fitting, line, or valve... 

I recently installed a V2 setup in place of my old manual setup, and so far everything is working flawlessy. I had some severe leaking issues immediately after install in the leader lines, but Jeremy at Airlift took care of that for me, I then tightened up some fittings, trimmed air lines and got it to the point where it would not leak at all during the day or when driving. I drove 20 minutes from a friends house back home and the pressure did not change at all. 

My question is; what is considered "normal" leakdown for a tank and bags while they sit overnight? I cannot imagine that any system is 100% leak proof, or holds the same pressure for long periods of time while sitting. 

Last night at 7:30PM I aired the car up to 55psi in the front, and 48 psi in the rear and allowed the tank to fill to 148psi. I live in MN where the temp is pretty unpredictable, yesterday the ambient temperature was 70 degrees with sunshine, and then dropped down to something like 45 overnight. I just went outside to check it today (exactly 24 hours later, the car was NOT driven) and the fronts were both at 48psi, the left rear was still at 48psi, and the right rear was at 41psi, while the tank was at 128. Today the ambient temperature reached 68 with clouds, but the car was still in the cool garage so it was probably more like 55. 

I took one semester of engineering in college before I switched majors, but never learned much about air pressure as it relates to temperature. I do know that car tires seem to inflate themselves when they get warm and deflate when they get cold due to ambient temperature. 

For the right rear, it seems as though I have a very slight leak, I'm assuming that trimming the air line and reconnecting it will solve the issue. As for the others, I believe that the pressure lost in the fronts was probably due to the rapid decrease in temp overnight and the constant weight from the front of the car. As for the air tank, either the check valves are slowly leaking, or it too decreased because of temperature. The left rear didn't change (I'm guessing) because there is not much weight in the back of the car. I have checked every single fitting (including those on the bags) with soapy water and not a single air bubble emerges. I have sat and stared at them for at least 15 minutes just waiting for one bubble, but nothing happens. Every threaded fitting has been sealed with both teflon tape and Rectorseal 5. I also sprayed the foam on the ends of the compressors where the filters go, and not a single air bubble. I sprayed near all the ports on the V2 and not a single bubble either... I'm at a loss. 

I have pretty much used the best of everything with this setup (minus viair check valves): 

Airlift XL fronts 
Airlift rears 
Accuair 3 gallon aluminum tank 
(2) Viair 400cc compressors 
(2) SMC 3/8" water traps 
All brass tank fittings 
Park PTC bulkheads 
Copper hardline supply to V2 
Brand new Airlift leader lines in the front with brass Alkon PTC fittings 
Airlift nylon line to bags 
Parker PTC elbows on rear bags 

For a 24 hour period of not moving and not being in the heat, are these numbers normal? What kind of leakdown does everyone else have? Could my tank be cracked or have a structural leak? 


Pic for reference (the copper hardline for the air chuck has been replaced with a brass elbow and a copper straight piece):


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## rgarjr (May 19, 2012)

Believe it or not some dudes claim that their systems are leak free even after a few weeks. I personally don't care if mine leaks a little as long as a corner isn't dumped or air tanks really low overnight.


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## FlybyGLI (Jun 20, 2008)

rgarjr said:


> Believe it or not some dudes claim that their systems are leak free even after a few weeks. I personally don't care if mine leaks a little as long as a corner isn't dumped or air tanks really low overnight.


 I've heard people claim it as well, but I just assumed they live in areas where the overnight temp is still relatively high. In my case, I'm not sure if I have leaks, or if the rapid decrease in temp makes my system pressure lower. 

I feel the same way as you, as long as it's reliable I guess small leaks are ok, but I also think that conserving as much air as possible and reducing compressor use is a good thing. 

I will say that as average temp has gotten higher, the system pressure loss has decreased. Maybe when the overnight temps here are in the 60s still, there may be no change in pressure at all?


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## mannythechamp (Oct 21, 2009)

I've been having similar problems too.. not to long ago i had to buy new leader lines because the check valves on them went bad and were letting air back out through the compressor. :banghead: 

good luck hope to see some unique troubleshooting as i too spend time spraying away bottles of soapy water and starring lol :thumbup:


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## jonpwn (Aug 13, 2010)

air does expand when it gets warmer, and contracts when it gets cooler. a 20+ degree change is significant enough to cause a few psi difference, given that the tank remains the same shape. Exact same thing that happens to tires. although 20psi sounds a little bit too much. I would check everything, your air chuck, water traps, drain c*ck, etc. I know my parker water trap requires a lot of effort to close the drain valve completely. 

I'm not sure if you should use both teflon tape and pipe sealant. But since I have no factual information about this, I'll leave it for someone else to chime in. 

It seems as though three bags are leaking and one isn't. If the temperature changes all around the car, then all four corners should proportionally change in temperature. I'm not sure how v2 works as I am using manual management, so again i'll leave that for someone else to help you with. 

btw i don't know what the soapy water solution looks like after being sprayed out of a bottle. I would imagine it's bubbly to begin with because that's how windex looks like when you spray it out lol. I've been using a small brush and a bottle of water + a little bit of soap.


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## mannythechamp (Oct 21, 2009)

jonpwn said:


> It seems as though three bags are leaking and one isn't. If the temperature changes all around the car, then all four corners should proportionally change in temperature. I'm not sure how v2 works as I am using manual management, so again i'll leave that for someone else to help you with.
> 
> btw i don't know what the soapy water solution looks like after being sprayed out of a bottle. I would imagine it's bubbly to begin with because that's how windex looks like when you spray it out lol. I've been using a small brush and a bottle of water + a little bit of soap.


 i agree all 4 corners should see a similar drop and i don't feel like ambient air temp will drop 20 psi either, and v2 can give or take be 3% off which guestimates to about 0-3 psi off so for instance if i air out and leave my tank at 147 and i wake up at 144 i don't consider it a leak no if i find it at 12 then its leak time 

i have never tried the brush technique lol should give that a try and yes it goes on foamy and then i hope to see a bubble form out of it :thumbup:


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## FlybyGLI (Jun 20, 2008)

mannythechamp said:


> I've been having similar problems too.. not to long ago i had to buy new leader lines because the check valves on them went bad and were letting air back out through the compressor. :banghead:
> 
> good luck hope to see some unique troubleshooting as i too spend time spraying away bottles of soapy water and starring lol :thumbup:


 I plan on repeating the air-up and let-sit process a few more times before I make any more changes in the system or adjust air lines. I wish it would warm up here and we could get a night that is 60+ degrees, that way I would know if the drastic temp drop is the culprit. I definitely plan on ditching the Viair check valves regardless. 



jonpwn said:


> air does expand when it gets warmer, and contracts when it gets cooler. a 20+ degree change is significant enough to cause a few psi difference, given that the tank remains the same shape. Exact same thing that happens to tires. although 20psi sounds a little bit too much. I would check everything, your air chuck, water traps, drain c*ck, etc. I know my parker water trap requires a lot of effort to close the drain valve completely.


 I will check the valves on the water traps in the morning. I already checked the drain valve, but perhaps I will check it again in the morning as well. And I agree, 20psi in the tank seems like a lot, although it is just a 3 gallon tank. 



jonpwn said:


> I'm not sure if you should use both teflon tape and pipe sealant. But since I have no factual information about this, I'll leave it for someone else to chime in.


 I have heard of people using one or the other, and I have heard of people using both. I figured overkill is better than not having enough sealing. 



jonpwn said:


> It seems as though three bags are leaking and one isn't. If the temperature changes all around the car, then all four corners should proportionally change in temperature. I'm not sure how v2 works as I am using manual management, so again i'll leave that for someone else to help you with.


 The V2 has electronic valves which I would assume stay shut pretty securely. Worst case scenario is that a piece of teflon or sealant has lodged itself in one or all of the valves keeping it slightly open when the manifold is inactive, causing pressure to leak somewhere, but that would mean that the valve for the tank would have to be open too, allowing air to leak back into the tank, and out through a fitting. I have checked all the ports on the V2 and nothing is leaking. I'm gonna say the manifold is working properly. 



jonpwn said:


> btw i don't know what the soapy water solution looks like after being sprayed out of a bottle. I would imagine it's bubbly to begin with because that's how windex looks like when you spray it out lol. I've been using a small brush and a bottle of water + a little bit of soap.


 The mixture I made comes out as just a soapy water with minimal bubbles (unless I shake the bottle). I may try a less concentrated solution and dabbing it on with towel or maybe your brush method. I may also borrow a tool from work that is designed to detect air leaks in A/C systems. It alerts you with a loud beep any time the tip encounters fluctuations in air near the sensor tip. But I doubt my leaks are severe enough to trip the sensor.


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## FlybyGLI (Jun 20, 2008)

mannythechamp said:


> i agree all 4 corners should see a similar drop and i don't feel like ambient air temp will drop 20 psi either, and v2 can give or take be 3% off which guestimates to about 0-3 psi off so for instance if i air out and leave my tank at 147 and i wake up at 144 i don't consider it a leak no if i find it at 12 then its leak time
> 
> i have never tried the brush technique lol should give that a try and yes it goes on foamy and then i hope to see a bubble form out of it :thumbup:


 I agree as well about all 4 corners losing pressure equally, and it seems that they are except for one bag, which does not make sense to me, it should be the other way around. 

Given the V2 variance, do you think that a smaller tank size might have anything to do with it? As far as the quantity of air being let out or "shrunk", a 3 gallon tank would technically have less than a 5 gallon. So maybe my 20psi leak isn't that bad? 

The total pressure lost between 3 bags was 20psi and my total pressure lost in the tank was also 20 psi. I'm assuming this is just coincidence because the manifold is not leaking, and air can't leak into the tank just as the tank cant leak into the bags (otherwise the numbers would have been much different). 

I plan on getting the system to the point where it doesn't lose more than a few psi overnight, but I won't be able to accurately diagnose anything until it warms up here  

It's the most frustrating part about having air ride.


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## boradie sucht (Aug 12, 2012)

mine has never been completely leak free, but it also doesnt leak to much whee it becomes an issue.


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## mannythechamp (Oct 21, 2009)

FlybyGLI said:


> I agree as well about all 4 corners losing pressure equally, and it seems that they are except for one bag, which does not make sense to me, it should be the other way around.
> 
> Given the V2 variance, do you think that a smaller tank size might have anything to do with it? As far as the quantity of air being let out or "shrunk", a 3 gallon tank would technically have less than a 5 gallon. So maybe my 20psi leak isn't that bad?


 i still think you have a small leak the springs up with either vibrations or some form of movement or occasionally the problem is finding that leak when its leaking, 
good luck with your findings 

but i have lost a few pounds over night due to temp change i feel like the same amount should be lost in your because its pressure drop not volume of air lost.. ? so regardless of 3 or 5 or 7 i think t should be no more than maybe top 10 pounds like topsssss ! someone will correct me if im wrong good luck 

opcorn:


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## jonpwn (Aug 13, 2010)

my system was leak free for a few weeks then all of a sudden it started leaking again after I had drained the tank and water traps. What had happened was as i opened the drain c*ck, the entire fitting backed out of the tank just enough to cause a leak. Before that it was 100% sealed.


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## MechEngg (Jan 13, 2009)

My tank system is completely leak free, i left it for 2 weeks last summer and it didn't drop a single psi (i wasn't completely full). My right rear bag however isn't leak free and it sucks if i leave it aired up overnight  

However there is something that will cause pressure loss on a totally leak free system; having a safety/bleed valve right at your max pressure. If you have say 175psi bleed valve and 175psi in your tank, then the sun hits your car the air in the tank will expand when it gets hotter and it will stay at 175 because some pressure will bleed off. Then when your car cools down to the same temperature you started with, you will have less pressure than when you started. This is a function of the max temp of the day, pressure in the tank and the current ambient temp 
Pcurrent = Pmax x (Tcurrentambient/Tmax) assuming that your start point is at Pmax=Psafetyvalve 
with the pressure in absolute and the temp in kelvin.


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## helloterence (May 15, 2010)

MechEngg said:


> My tank system is completely leak free, i left it for 2 weeks last summer and it didn't drop a single psi (i wasn't completely full). My right rear bag however isn't leak free and it sucks if i leave it aired up overnight
> 
> However there is something that will cause pressure loss on a totally leak free system; having a safety/bleed valve right at your max pressure. If you have say 175psi bleed valve and 175psi in your tank, then the sun hits your car the air in the tank will expand when it gets hotter and it will stay at 175 because some pressure will bleed off. Then when your car cools down to the same temperature you started with, you will have less pressure than when you started. This is a function of the max temp of the day, pressure in the tank and the current ambient temp
> Pcurrent = Pmax x (Tcurrentambient/Tmax) assuming that your start point is at Pmax=Psafetyvalve
> with the pressure in absolute and the temp in kelvin.


 New to air suspension here. 

I hope to have a leak free system once I get my tank situation figured out. Been having some bad luck getting tanks with small leaks in the bungs (just got my 4th replacement tank from BR today). I keep my car at ride height throughout the night and don't notice any change. e-Level will make very minor adjustments when I start the car up but from what I understand, that's normal. 

By the way, thank you MechEngg for suggesting putting a check valve in between the tank and the manifold. I will be having that done tomorrow along with the VIAIR check valve replaced and new tank installed. Fingers crossed that everything goes as planned and no more stressing! :thumbup:


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## jun_1.8T (Oct 31, 2003)

To the OP...im sorry to hi-jack your thread but i wanna share my experience too.

I recently installed my air ride. Everything was perfect except for the driver's rear bag. It would read all the time about 10-15psi less than the other if I leave it for more than 8hrs. I was gonna take it this weekend but i noticed something from monday. It seems to be holding the pressure now and is always almost the same as the other rear bag. Its been really warm up here for the past few days. 

You think its just got something to do with the outside temp? All my other bags and management is leak-proof.


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## choey (Feb 11, 2007)

I always lose a few psi in my bags over night and its mostly because of the temp changes I believe. 

I have noticed that my air tank has been going up from say 143 to 150 through out the day as it gets warmer here.


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## FlybyGLI (Jun 20, 2008)

helloterence said:


> New to air suspension here.
> 
> I hope to have a leak free system once I get my tank situation figured out. Been having some bad luck getting tanks with small leaks in the bungs (just got my 4th replacement tank from BR today). I keep my car at ride height throughout the night and don't notice any change. e-Level will make very minor adjustments when I start the car up but from what I understand, that's normal.
> 
> By the way, thank you MechEngg for suggesting putting a check valve in between the tank and the manifold. I will be having that done tomorrow along with the VIAIR check valve replaced and new tank installed. Fingers crossed that everything goes as planned and no more stressing! :thumbup:


 Sorry to hear about the defective tanks. I'm just hoping that's not my issue. I waited 4 weeks to get the one that I have in the first place. And I may try the check valve before the manifold too. 



jun_1.8T said:


> To the OP...im sorry to hi-jack your thread but i wanna share my experience too.
> 
> I recently installed my air ride. Everything was perfect except for the driver's rear bag. It would read all the time about 10-15psi less than the other if I leave it for more than 8hrs. I was gonna take it this weekend but i noticed something from monday. It seems to be holding the pressure now and is always almost the same as the other rear bag. Its been really warm up here for the past few days.
> 
> You think its just got something to do with the outside temp? All my other bags and management is leak-proof.


 
No worries, sounds like you are having similar issues. I definitely think its temperature related. 

A little update on mine. I drove it to Old Chicago last night, about 2 miles from home. I returned home at about 9:45PM and the temp was 40 degrees. I left the fronts at 55psi again and the rears at 47psi. I went outside this morning at 9:45AM, so exactly 12 hours later, and the fronts were at 53, and left rear was at 46psi while the right rear was at 45psi. The tank was at 128psi but unfortunately I do not remember what I left it at, I know that I didn't fill it. So it seems that over 12 hours there really isn't any issues given the cold weather. It's going to be miserable weather here for the next 4 days, so I aired it up again and I will check on it tomorrow.


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## MechEngg (Jan 13, 2009)

^^That is definitely temperature related.


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## leftygibsonplyr (Feb 16, 2006)

I dont lose pressure in the bags (or if i do, i sure don't notice it when i get in). I lose maybe 5-10psi in the tank overnight though...I think thats kinda "normal" though with temp changes and such...especially when its maybe 60 during the day and 40's at night. :thumbup:


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