Which Air Spring?

[RF Overlord]

I suppose I need to apply some soap to the bags, and see if I can detect any leaks, but I'm pretty sure air bags don't leak intermittently.

No, but the solenoids might.

Could I have an intermittent purge valve? Could my dryer desiccant be used up, causing moisture problems?

The vent valve is part of the compressor...it *could* be leaking, but only if the solenoids were commanded open at the same time, unless both the solenoids AND the vent valve are bad..

Moisture will cause corrosion of the internal workings of the compressor or cause a line blockage in freezing weather, but would not cause an intermittent leak in June.

[Wires]

No, but the solenoids might.

The vent valve is part of the compressor...it *could* be leaking, but only if the solenoids were commanded open at the same time, unless both the solenoids AND the vent valve are bad..

Moisture will cause corrosion of the internal workings of the compressor or cause a line blockage in freezing weather, but would not cause an intermittent leak in June.

Intermittent solenoid is my thought as well. I suppose my knowledge of the system's operation is deficient. The car isn't listing. That indicates to me that both of the air spring solenoids are open, so whatever is leaking, air spring or valve is affecting both bags equally.

However, I can't believe that both solenoids are open when the car is parked.

Incidentally, it is a bit cooler today, so I got the car out for a brief drive. The level hadn't dropped enough to trigger the pump to add any air. This is after 5 and a half days. Previously, it would be setting on the stops after only 2-2.5 days.

[juno]

I went with Arnott's just FYI.

[vegasmarauder]

I went back through the paperwork I collected over the years. According the "as built" factory printount (could get those from the dealer years ago) on a 300B built February 2003 the rear air bags carried the part number XW73-5A891-AA. This decodes as a 1999 Crown Vic air spring, first engineering version. Can't tell if its a HPP spring or not. I also found a printout of a very old MM.net post that said someone had contacted Arnott and they only sell the heavier bags for CV/MGM/TC/MM. These were reffered to as "Limo bags" because of the extra weight of the Lincoln limos. That was the listing for the MM.

I have used the Arnott bags and kits for several years in a few MMs and I have not noticed a difference in the ride or handling from original. I know Arnott re-uses the tops and bottoms sent in as cores so I'm not sure the Black/cream color difference holds the same on the replacement bags.

By the way, the "as built" printouts is a multi page document that lists every part number of every componet used on a particular car during factory assembly, such as wiring harnesses, springs, trans (MM carried a 2002 MGM part number), steering, trim, speedometers, etc. It is what the parts guy is supposed to check if there is a confusion when looking up a part. In the event the factory had to deviate from a standard part because of availibility, etc.

Hope I added some info and not more confusion.

EDIT: Did some research with with my parts friend. In the Ford parts system, the as built air bag number crosses over after a few changes to the AA suffix number listed above. As near as I can tell the PA number is for the Town Car and may be a softer spring.

[Wires]

Thanks for the info. My problem now is that I'm no longer certain I need springs.

I can't find any leaks. Lately the car has done better. It wasn't low enough Saturday to run the compresor, and after I put it back in the garage on Saturday, it still hasn't lowered significantly. (Today is Wednesday)

I suppose I should start another thread about the operation of the system, as that's my question, now.

I know there is a purge solenoid in the compressor, and that the line goes to a "T," then to both bags, where there is also a solenoid. I don't know if these bag solenoids can vent to atmosphere, or if they just close or open the bag to the common line.

The car doesn't lean, so any leak is affecting both sides. I didn't detect any leaks,and the rubber looks to be in good condition. If a solenoid were bad, how/why are both sides affected equally? Are both bag solenoids open even when the car is parked? I seriously doubt a bag or bag solenoid could leak the same on both sides. Somehow, the pressure is equalizing.

I'm not expert on searching, but I can't find a simple explanation to how the system works. (other than the compressor pumps both bags or vents depending on the sensor position) I need further details to figure out what's wrong. The intermittent nature of the problem isn't helping.

[fastblackmerc]

Thanks for the info. My problem now is that I'm no longer certain I need springs.

I can't find any leaks. Lately the car has done better. It wasn't low enough Saturday to run the compresor, and after I put it back in the garage on Saturday, it still hasn't lowered significantly. (Today is Wednesday)

I suppose I should start another thread about the operation of the system, as that's my question, now.

I know there is a purge solenoid in the compressor, and that the line goes to a "T," then to both bags, where there is also a solenoid. I don't know if these bag solenoids can vent to atmosphere, or if they just close or open the bag to the common line.

The car doesn't lean, so any leak is affecting both sides. I didn't detect any leaks,and the rubber looks to be in good condition. If a solenoid were bad, how/why are both sides affected equally? Are both bag solenoids open even when the car is parked? I seriously doubt a bag or bag solenoid could leak the same on both sides. Somehow, the pressure is equalizing.

I'm not expert on searching, but I can't find a simple explanation to how the system works. (other than the compressor pumps both bags or vents depending on the sensor position) I need further details to figure out what's wrong. The intermittent nature of the problem isn't helping.

I believe there is info in the Shop Manual. I'll check when I get home.

[RF Overlord]

I can't find a simple explanation to how the system works.

Best information I've seen is here.

[lifespeed]

I have used the Arnott bags and kits for several years in a few MMs and I have not noticed a difference in the ride or handling from original. I know Arnott re-uses the tops and bottoms sent in as cores so I'm not sure the Black/cream color difference holds the same on the replacement bags.

The Arnott air springs I bought had an aluminum bottom piston, I don't remember what the top was made of. They clearly were not re-used from core OEM air springs.

[lifespeed]

Thanks for the info. My problem now is that I'm no longer certain I need springs.

I can't find any leaks. Lately the car has done better. It wasn't low enough Saturday to run the compresor, and after I put it back in the garage on Saturday, it still hasn't lowered significantly. (Today is Wednesday).

Changing temperature?

[vegasmarauder]

To follow up on a previous post I made. Edited the original post too.

EDIT: Did some research with with my parts friend. In the Ford parts system, the as built air bag number crosses over after a few changes to the AA suffix number listed above. As near as I can tell the PA number is for the Town Car and may be a softer spring.

Also, I would lean towards a problem with the ride sensor not functioning correctly. If the compressor and bags are functioning the next componet prone to failure is the ride height sensor on the back axle. Its out in the weather all the time. We had one that seemed to have a dead spot in the sensor.

[lifespeed]

EDIT: Did some research with with my parts friend. In the Ford parts system, the as built air bag number crosses over after a few changes to the AA suffix number listed above. As near as I can tell the PA number is for the Town Car and may be a softer spring.

The Marauder uses Town Car air springs which are 102 lbs/in vs 89 lbs/inch for CV/GM. The town car is longer and heavier.

[Wires]

I thank everyone for the info and for the help.

I don't think the sensor is my problem because every time the car is low (sunk) I turn the ignition on, close the door, and it pumps up to the proper height and stops.

My confusion is the fact that the rate of lowering changes. Someone said it could be temperature related. Right now I don't suspect the springs, but that's only because I don't seem to know anything right now, except for:

1. It doesn't lean. Both sides are affected normally.
2. It behaves differently, possibly due to temperature.

I believe the system is only on for 1 hour after parking. So, if it gets warm, and the air in the bags heats up, how would it vent to cause the car to sink when it gets cooler? Also, are both spring valves ever open even when parked? How do both bags remain equal despite any leak that may exist?