Symptoms of a rear air bag leak/how low does the suspension go?

Ricky Bobby · #1 08-02-2013, 08:26 AM

Guys, been dealing with air suspension issues recently and wondering if someone could shed some light here. My front air struts were replaced in January 2012 with Arnott units, work excellently. I also replaced my compressor as it was burnt out of spec at that point (had I known about the seal fix to get the compressor working I would have went that route). I don't know if the previous owner ever replaced the rear air bags, but when my fronts were replaced, the indy shop said they tested the system and the "rears were fine".

Well fast forward a year and a half and what I think might be ride height issues turns out that my left rear corner is sagging more than the right rear. I wanted to let the X sit for 24 hours so I could check to see if it lost any more height but it is already fairly low, approx. 27 1/4 inches from rim flange to fender (20" wheels), whereas the right rear is about 3/4 inches above that.

My question is, when the front air struts were blown, they literally were basically touching fender to top of tire, until the car started and they could be pumped back up when the car is running. Correct me if I'm wrong, but even if the rear bag or bags are leaking doesn't the rear shock only allow them to "sag" a certain amount (unless calibrated to be lower than that) because of the static load on the rear suspension? So even if they were blown completely they wouldn't be riding completely on top of the tire like the fronts were?

Oh yeah, and I've had a random SELFLEVELSUSP INACT errors the past week or so, they would pop on and go away, but last night when I went to get take out, it popped on and stayed on, so I can't even pump the car up to offroad height to get a better look at the bag.

Got under the car last night and looked at the base of the bag with a flashlight, the right rear doesn't show any hairline cracks that I can see, all height sensors look fine, but the left had a few tiny small cracks, I will test with soapy water tonight to see if I have bubbles (although if the corner is lower that will tell me enough)

Basically if I have a leaking rear, I'm trying to catch it as soon as I can to avoid blowing out the compressor (again).

Thanks!

upallnight · #2 08-02-2013, 08:33 AM

If you need to replace an air bag, you should do both.

Ricky Bobby · #3 08-02-2013, 08:57 AM

Quote:

Originally Posted by upallnight

If you need to replace an air bag, you should do both.

x2 I definitely would if one is leaking (at 200 bucks the Arnott replacements are awesome)! I just want to be sure it is definitely a slow leak first, because the symptoms are unlike when my fronts were completely blown

(overnight my front would lose air completely and the fender would be touching the top of the tire they were so bad)

DTMdan · #4 08-02-2013, 08:53 AM

Bro, slam it bro.

X5SND · #5 08-02-2013, 11:43 AM

In regards to your bold section Ricky, if you're losing air in a bag, it will sag until the load equalizes...if you lose all air, it will drop until the X is resting on the bump stops (which are located atop the rear shocks). The shocks have negligible effect on preventing the X from bottoming out in the event of minimal air in a bag.

Ricky Bobby · #6 08-02-2013, 11:54 AM

Thanks S,

Will check out with soapy water later on, I suspect my left rear bag has a slow leak, and even if not, if they are original (at 10 years old), they will be replaced. 10 year old air bags are a sign of trouble waiting to happen.

X5SND · #7 08-02-2013, 01:54 PM

You probably already know is... If you're going to soap down the bag, jack the X up so you get moderate extension on the bag. This way you'll be able to soap the part that forms the rolling edge.

Ricky Bobby · #8 08-02-2013, 01:57 PM

Quote:

Originally Posted by X5SND

You probably already know is... If you're going to soap down the bag, jack the X up so you get moderate extension on the bag. This way you'll be able to soap the part that forms the rolling edge.

yes I do S but your help is always extremely appreciated!

I think of it this way, if my bag is leaking and I have to order replacements, at least I will be able to get caught up on the other things I have to do while waiting for them to come in the mail (painting calipers, replacing intake boot, fitting the HID's to the fogs, etc!) and when I won't be driving my X!

X5SND · #9 08-02-2013, 02:09 PM

I have to do that intake boot as well... Except some a-hole (me) some how managed to tighten the clamp last time when I did my Ccv before I put everything else back in place so now it's a huge PITA to access! Lol.

What color you doin the calipers??

Ricky Bobby · #10 08-02-2013, 02:40 PM

same color I like my tuxedos, black.

G2 caliper paint, bought 4 new anti-rattle clips too as they are all rusted status (and I think it is extremely tacky to the guys who paint the rattle clips on the caliper, lazy IMO).

I think the intake boot will be tougher than I think, those clamps really are a bitch to get to.