Rear End Dropped - Air Suspension?

[leximus]

I have a 91 LS400 automatic with air suspension (also with the Height control switch near the shifter). I've searched the forums but can't get a true answer. The other day I was on the highway doing about 81 or so. The car's suspension kicks into low at this point. When I got off the highway and got home, I noticed the rear end was lower than the front end.

Today I went out with the family and the car's rear end completely dropped. It is still drivable, however, I'm unsure what the problem is. Someone told me it may be the "air" pump, or hoses or is it the struts? Also, someone told me that I could "override" the air suspension struts and fit it with regular struts. Is this true?

I'm looking for help in determining what is wrong and is it safe to drive as this is my only means of transportation.

Thanks in advance for your help.

[SKperformance]

If only one corner is down then it would likely be a strut or possible a line before a separating valve.

If the whole rear end is down it is more likely a line.

If your compressor was gone then the whole car would be down.

[leximus]

If the whole rear end is down it is more likely a line.

Is it called the "air line"? Is this possible to fix myself, the line, that is? What type of parts would I need to purchase in addition to?

I truly appreciate your help.

Thanks,

Leximus

[W201 sweden]

Hello Leximus!

I hope I don't sound rude or offending, but judging by your previous post, I'd say you ought to leave this to a professional! B)

Suspension, steering and brakes are too important to handle for the less experienced person - in my opinion.

Perhaps you can still participate during the repair, and pick up some more info for the future? :)

best regards,

Alexander from Sweden

[SKperformance]

It all depends where the leak is on how hard it is to fix it.

[W201 sweden]

Yes, SKperformance - that's exactly why a pro/skilled technician should check it out. Neither you or I can diagnose and "repair"

HIS car with 100% accuracy without actually BEING there? ;)

There are so many better "starters" for DIY, so why start messing with such important stuff? B)

By the way, SKperformance; Nice pics of your car! B)

/Alexander from Sweden

[leximus]

The whole car is sitting low now. Where is the compressor located? Additionally, anyone know where I can find a repair manual in PDF format or order a repair manual so I can at least research this issue a little deeper?

[jainla]

You can try this:

http://us.lexusownersclub.com/forums/index...showtopic=30802

also techinfo.toyota.com lets you subscribe for $10 for 24 hours. I agree with the other posters that the Air suspension is a complex piece of machinery that may not really a DIY fixer depending on how handy you are with these kind of things. .

A dealer or independent will probably be able to at least tell you what's broken, then you can decide if you want to attempt the repair yourself or let them do it. They can probably pressure-test the system to see what's leaking. I believe there is a cross-feed valve somewhere in or near the trunk that might explain the rear drop problem; but the whole car is much more serious. The compressor is in the engine bay somewhere; the repair manual will have a more complete diagram of the system.

Does it raise up when you start it or stay down? If it's not going up the compressor is either shot or the leak is too large for it to overcome....If you have a leaking line or strut the compressor will work overtime trying to keep the system pressurized and eventually burn out. Do a search for Air suspension and see if other people have reported similar problems....this is a popular topic of debate around here. :chairshot:

I would get the car to a dealer or a good independent for diagnosis sooner rather than later.

If you decide to repair the system you can buy aftermarket air springs, search these forums for Arnott industries they seem to be the only aftermarket supplier. I have also heard of people getting good prices on the OEM springs from Carson Toyota here in LA, but even the best price you'll find is about $300 per strut.

The retail price from most dealers is probably $1000 per strut (ouch) so your second option is to purchase an aftermarket spring/shock combo that fits where the airsprings would go. Again many people on these forums have all gone through this so a good search will yield some options and suggestions.

Good Luck!

[leximus]

Thanks for the info. I called my mechanic to see if he would be able to at least look at the lines to see if there was a leak. He looked into the computer under 91's and said it only brought back 94's (and on) with air ride/air suspension. I told him I had the height control also, but he said that the earliest brought back was a 94. Am I communicating wrong information to him? I need to get this fixed right away and thought it was the air suspension that had a leak because all fours are lowered literally to about 6-8 inches off the ground. Not the best ride at all.

I need help....

[leximus]

I know when you hit the Height button and set it to High and you zoom past 80mph that the Height Indicator in the dash changes to Normal, or if set to Normal it hits Lo. Is there a height sensor that is related to the air suspension? Could this be the issue? As you already know my suspension is dropped as low as it can go and I was on the freeway this AM (yes, this is my only means of transportation) on my way to work and I hit 83mph to see if my Height Indicator (which was set to High) would change to Normal and it didn't.

Additionally, for my future reference and anyone else's, what does the Sport Mode set to On do to the car and can this be played with while the Height button is not set to Normal?

Thanks again for all your help!

Leximus

[dfkd]

Invariably you have a leak.

If any sensor was in err the system would flash normal.

There is a height sensor at each wheel that the system uses to know when each wheel is at the correct height (there is always a different amount of weight on each wheel).

The Sport Mode instructs the system to stiffen the shocks to reduce pitch and roll in cornering and braking and it also sets the system to reduce the steering power assist. Effect is the same at any height.

Airsus was available from the beginning (1990) contrary to what your mechanic thinks he knows.

[leximus]

Is the leak a fairly easy job for a mechanic? What would the fix entail...lines/valves? You don't think my compressor is shot do you? Would you think my airsus struts are still in good condition because one day they were all fine and the next, they're down low. How about pricing? I know this could vary, but average?

Also, the only time my Normal height mode flashes, that I know of, is if I turn the switch off in the tool kit box in the trunk. I've never experienced it otherwise.

[dfkd]

Well from your symptoms (assuming that it's the rear end that is still lower than the front as per the first post), it's the line that goes from the front to the back of the car because if it was one rear shock (air bag), then one side of the back would be lower than the other, logically, as each wheel is managed independently.

If the front is still up then your compressor should be fine.

So in this case it would seem that it would be a bad line/valve that is leaking. Fixing it then, would entail finding a replacement line/valve and installing it. I'd also say you start with the lines because they are cheaper then getting the shocks.

I think most of your cost would be in diagnostics.

I've done a full transplant and repair (diagnostics, line replacement and shock replacement), and i've also done complete conversions with my father back in Trinidad (we worked on Toyota Crowns...same system). We did leak searched the classic way (soapy water) and it worked everytime. Just takes time and effort.

The leak could even be something as simple as an o-ring. There are 2 of those on each screw-in connection.

About the prices, I have no idea what it would cost here because in Trinidad we imported the stuff ourselves directly from Japan.

[leximus]

I may have miscommunicated previously. Now the entire suspension is low. Would that be the compressor or possibly still a leak in the system?

[dfkd]

Damn...this just got a lot harder to diag.

It could also be the pump then.

You just need to get it checked out dude. And by someone who knows what they're doing.

Perhaps the dealer could figure out what's wrong and, if you're the type, you could do the repair yourself.

[jainla]

Air ride has been available since the start of the LS run....the 90-94 systems should be very simliar (because they are all MKI cars); I expect most of the components are in the same place so the schematics etc. should be valid.

Did your mechanic check out the http://techinfo.lexus.com/ site? Where was he looking?

On the 01 cars there is a height sensor on both the front and rear suspensions...it seems to be underneath the car at midline (near the differential on the rear and steering rack on the front).

You may also want to check the fuses, perhaps the one that runs the compressor or the airsus system has blown?

[leximus]

I'm convinced it's either a leak or the pump. Why would all four airbags just collapse at one time? I had called my mechanic to get some prices for new airbags. He was quoted 1k a piece. I don't think I'll be throwing that money into my car. Probably better off obtaining aftermarket struts to convert if the airbags are shot, if that's the final say.

If not, Hopefully it's just the leak or the compressor/pump. Those two options would definitely be cheaper than installing new airbags or even converting.

[dfkd]

There are cheaper airbags than that...

http://www.arnottindustries.com/parts_Lexu...400__yid46.html

There you can get them for about 400 each.

I agree with what you said thoug...they wouldnt all go at the exact same time so i guess you just need to find the real problem.

The pump should be easy to diag cause with the car down like this, it should be running full time to try to raise it if there's a leak in a line.

If you go to it and it's not running you can start by changing that.

Arnott sells the pump for $300.

Good luck.

[wandawoods]

I'm convinced it's either a leak or the pump. Why would all four airbags just collapse at one time? I had called my mechanic to get some prices for new airbags. He was quoted 1k a piece. I don't think I'll be throwing that money into my car. Probably better off obtaining aftermarket struts to convert if the airbags are shot, if that's the final say.

If not, Hopefully it's just the leak or the compressor/pump. Those two options would definitely be cheaper than installing new airbags or even converting.

air sus woes for 1st gen LS were well discussed in the past in this forum. if you were to convert, here is a good tutorial:

http://www.lextreme.com/ascon.html

$650 for set of 4 "strut master" conversion kit plus about 3~4 hours labor. the rear pair are pins in the butt, you must remove rear seats in order to remove old air struts. do expect a "stiffer" ride after conversion, though!