1998 Mark VIII Air Ride Trouble


LVC Member
Jul 20, 2019
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Queen Creek, Arizona
Morning gents,

One step forward, two back.

I was planning a trip; it had been a while since the last brake inspection, so, I turned the air ride off at the switch, jacked up the car, rear to front, did my thing, lowered the car and turned the air ride back on. Since then, after 24 hours, the front bags are dropping. They do immediately pump-up once the car is started but drop again after sitting for another day. No work was performed on the suspension, and the rear bags are not affected at all. Any help will be appreciated.
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Got to start looking for leaks
Most common are the bags but if your lucky it may be the bad Solenoid or solenoid o rings
Thanks. I agree that is the obvious, I was just hoping under the circumstances that maybe it could be something attributable to the raising of the car which I know sounds strange. These cars are quirky.

After I posted this yesterday, I went out and disconnected the battery and waited about 10 minutes. Turned the AR switch off, started the car, shut it off, turned the switch on, started the car, front bags filled, and I took it for an hour drive. AR functioned properly at freeway speed and at full stops. Came home, checked after 6 hours it was fine, just checked it before sitting here and the suspension was still up and level.

As I said, quirky. I appreciate your input, thanks again.
Well, not as simple as I thought.

Front of car continually drops at about 48 hours; back is fine. I did allow the bags to fill, turned the AR switch off, drove the car for 40/50 miles, came home, parked with the switch remaining off, and the car never dropped after 6 plus days. I cannot find any leaks. Unfortunately, my mechanic had retired, the shop doesn't want to take a look and I don't have a SS II scanner. The front ride sensors are still available; is the next step possibly there?

The easy thing to do would be go to coils but I'm a purist. I'll sell the car first and let someone else convert it if they choose.

Just frustrated, any/all help would be appreciated, greatly so. Just seems odd that it went from fine to not so with one mere lifting to check the brakes.
Your front air shocks are cracked around the edges where the car would normally sit at parked height. Two days isn't bad, but it will get worse with time. When you turned the switch on and let it air up again, it usually will go above where the parking height is.

What you done was turned the switch off (with door open) before it had a chance to vent down to park height. This means it's above the cracks and will hold air longer. The more it drops and aggravates the cracks, the quicker it'll start dropping.

You can either buy some new ones for around $175 each, or turn the switch on as soon as you see it coming down. Turn it off before closing your door. Letting the door close causes it to vent down.

New ones by Westar and Arnott usually last a few years, maybe a little longer.

I'm also still on air and will never convert. I bought one of the last pairs of Motorcraft Gen 2 air shocks before they were discontinued and they're still good, but in another 10 years, I'll be where you are now. I have Westar air springs in the rear and haven't had any issues with them.

Good luck with it!

Ther other thing it could be, is on the top of your air shocks, there is a rubber bushing where it mounts. Those have been known to leak, but rare. You can take the shock tower cover off and spray soapy water and look for bubbles. It's likely only a problem with one of them, and not both.

When one leaks, the other one cannot hold the weight of the front end by itself, which causes it to drop. I'm still on the side of one of them having cracks. When the air bladder is vented down to the fold where the cracks are, then it will leak quicker.

When it gets cold out, expect it to drop a bit quicker. It's almost impossible to look at the bag in the car and see the cracks. Even if you had it laying in your lap, you'd still have a hard time seeing them.

I'm not recommending this, but some have put slime in the bladder and let it go to the bottom where the cracks are. Once it's down there, tilt it enough so that it soaks into the cracks and turn it while tilting. "THEY SAY" that the slime will remain at the bottom of the bladder and never come back into the system. I've never done it but many have in the past and I guess had good results.

Below is a pic of a leaking bag. This was mine back in 2012. Over the years of going up and down, the rubber started attaching itself to the bottom. This resulted in the bladder being thinner. Then the cracks started leaking when right at that fold. Only one leaked but the whole front would drop when my garage reached the mid 40's. Only one alone can't hold the weight. Hopefully you'll find what's wrong pretty soon.

Thanks for this Terry, I am very grateful.

The thing has me scratching my head...and I haven't pulled the wheels again for better access.


I have been led to believe that if the switch is turned off and the car is driven (with switch off), letting it sit (this sat for almost 1 week with switch off) if the car doesn't drop it isn't the bag itself, it is else. Is this not as tried and true a method as I have assumed.

What I don't remember is the car ever venting after I got in it to move it to the garage and the front was higher than ride height. It didn't vent until later...once lowered, with the switch on again, shouldn't it have returned to operating as designed?

Forgive the thinking out loud. Again, thanks much.

If you let it air up, and you get out of the car to turn the switch off, the car will only vent down when the door is shut. It doesn't always vent immediately, but it can... It could be within 5 seconds, or minutes later. The air ride is active for 45 minutes after the car is shut off.

You could shut the car off, go inside and eat dinner within 30 minutes. The air ride could air up again while you're inside eating, and you would never know.

So, this is what I would do if I were you.

1. Air it up while it is sitting on level surface, garage floor would be perfect. Once it's done, get out and shut the door. Make sure you see it vent down. Once it vents, turn the air switch off. Take note of the time.

2. Measure from the floor to the bottom of the fender opening, dead center above the tire. Measure both sides. Write them down and when the car does start sagging in the front, take measurements again. Whichever side is lowest is the culprit.

3. Final test: Turn the switch on and get inside the car, then shut the door. Let it air all the way up and then get out, leave the door open. Cut the switch off and measure again. See if the first measurements are the same as the 2nd set. If it's setting a little higher, let it sit there and see how long it takes to sag in the front, if it even does.

If you have to drive it, go ahead, but when it starts sagging, measure again to see which side is lowest.
Okay guys, the saga continues.

I checked with shop sources and no takers. Also, couldn't find a Rotunda SS II to borrow...but I did find one to purchase; these are quite nice (and I could kick myself in the hinder parts for not buying one years ago.

Here is what I have for codes:

* 35 - EVO actuator.
* 99 - Unable to detect raising or lowering.

Any takers? Thanks in advance.
With the 99 I would say do the sound test on each of the 3 ride hight sensors
Ignore the 35 for now
Okay. We have had a few days of bad weather (for Arizona this time of year), but I just ran the tests again.

I made sure there were no codes in memory; I ran all the tests pertaining to the sensors and everything checked audibly, including at the compressor. I finished with these, and the only code (no code) was "15".

I went back through, all tests (211-227), no codes other than "15". Ran this process an additional time, and again no other codes. The "35 and 99" from the prior test do not exist.

This maybe a dumb question: but by 'its' absence is there a possibility that the module has an issue? The way this all started has 'electronics' written all over it...but that is a sense not a defendable conclusion. On older Harley's, we called them gremlins.

Again, any help is greatly appreciated.

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