Last week, I took my 91 awd to the garage because of the way it was driving (jerk, thump like tire flat, etc.) I was told that the problem was in the 4 wheel drive part (spider?) and a decision was made to remove it making it only 2wd. I paid them over 300.00 only to drive it a few miles with a slight transmission slip, then parked it. The next time I got in it, it would not move at all!

As I'm sure you can tell, I'm a female that doesn't know a lot about this kind of stuff so be gentle with me.

 

welcome 48fan,


do you know which part they removed or disconnnected?

All Wheel Drive computer under driver seat?

can you take a digital pic and post?

was this a Ford dealer garage?

 

sounds like you played SANTA to the guys kids....

 

I'm not sure about the parts but will try and find out.

There is something under the seat so I suppose that's it.

It was not a ford dealer.

I have a digital camera. What do I need to take picture of?

 

That's what I've been thinking too! Worst part about it is my kids went without because it!

 

the part they removed or disconnected so that we can identify

 

Okay. I'll get back to ya.

Thanks!

 

The reciept I got from them states....

VEHICLE INSPECTION. 3 NOISE REAR END
REMOVE PT. DRIVE SHAFT & AXELS

 

Gee, if that's what I think it is, those mechanics were terribly ignorant of the way the car works, and may have caused major damage to the transfer case. It looks like they removed the front drive shafts, which is what you would do to turn it into 2wd in other types of 4wd vehicles. The Aerostar is a full time AWD, and can not be made into 2wd. The quickest solution to the problems you were seeing would have been to remove the 4wd control module under the driver's seat. The car remains in full time AWD mode, but without the front/rear lockup capabilites. That's what it was doing incorrectly, which caused the clunky conditions you experienced.

You need to have those jokers re-install the parts that they took out (which, I might ad, they overcharged for). Otherwise, your van will go nowhere.

As for the cause of the incorrect lock-ups of your transfer case, there may be many, including excessively worn front tires, or oil leakages on some of the sensors used by the AWD system. But I think it is safe to run the vehicle without the lock-up by disconnecting the control module.

 

I called the garage and told them what you said only to get an argument back. He said that the "front differential"? was bad? I asked if he even unhooked the thing under seat and his smartass remark was, "no, we did not". Says that nothing they done caused this and I needed to get the transmission looked at.

 

While it is possible that the transmission may be overdue for a service, I don't think that old fluid is going to cause this. This guy is jerking you around. My van has a clunking in hard turns, the problem is the speed sensors. If I unhook the module under the drivers seat, the clunking goes away. If the differential was bad, the clunking would not go away. Take it to someone else who does free diagnostics. There are transmission shops that do, and they are generally considered to be more reputable in my eyes.

Here is the lowdown on how the AWD system in these vans works. There is a transfer case that intercepts the driveline as it heads to the rear wheels. It takes some of the power from that driveshaft and runs it through a viscous clutch, which is basically a bunch of thin discs that sort of mesh together without actually touching. They are suspended in a thick grease about the consistency of honey. As the discs connected to the driveshaft spin, it causes the other set of discs to want to spin also, this is connected to a shaft that runs to the front wheels and makes them spin. There is some sort of mechanism, which I do not fully understand, in this, that is controlled by the ABS computer. The computer reads the wheel speeds, and watches for discrepancies in their motion. If one of the wheels is spinning significantly faster than the others, it knows that wheell is slipping. Since the vehicle is still dominantly RWD, the rear wheels will almost always start slipping first. When this happens, it locks up some stuff, and transfers more power to the from wheels in an attempt to control the slipping. When in this AWD lockup mode, the front wheels loose much of their freedom to spin independandtly. So tension will build up between the front and rear wheels when you turn sharply, and this can be felt as a clunking or hard shuddering. This can easily be duplicated in most 4WD trucks by turning on 4WD and turning sharply on dry pavement. The quickest fix is to unplug AWD module under the seat, no computer means no AWD lockup. There is still roughly a 30% torque transfer to the fronts, but since the viscous clutches can still turn freely, the tension never builds up. My complete transmission service including new fluid in the tranny, transfer case, minor repairs and service on the transfer case, new filter, new modulator, new gaskets on both the tranny and the transfer case, and basic diagnostics cost me $285 USD.

 

That van has been my pride and joy ever since I've had it. It has lots of miles on it but will still outrun anything out there! In fact, I've got the speeding ticket from my last trip (biloxi to missouri and back) to show for it.

It was only in town when I was going slow that I ever had any of that trouble. I just wanted to get it looked at and fixed cause I was planning a trip for xmas to my daughter's in Florida and didn't want to mess anything up.

Needless to say, I never made it to my daughter's and my van's messed up!
I'd give anything to have found you guys earlier! This makes me sick!

Thank you for helping me!

 

48fan,

I hope you got all the parts that those mechanics removed. You will need them to get your van to go again. That they did not know about the AWD control module indicates that they do not understand how this system works. Since the van won't move without those parts, you will have to either have someone come to your home to re-install them, or have it towed to a competent mechanic. You can make this proposition to the guys who did the work originally: If after they re-install the parts, and the van moves again, then it proves they screwed up. If the van starts clunking again, you can remove that module to see if it goes away. Then they should pay for their mistakes.

Khanty worte:

>but since the viscous clutches can still turn freely

You are describing a viscous coupling, but that's not how the AWD system in the Aerostar works. It is a wet clutch pack that is engaged by an electromagnet when the control module detects sufficient speed differences between the front and rear wheels; it does not rely on viscous fluids. The speed sensors are in the transfer case and rear differential. It's not just the rear wheels that can lose traction, so the control module just locks both ends together. In a turn, all wheels will turn at different rates, so a locked differential causes severe binding. The effect is usually the worst at low speeds, since that's when you're most likely to make the sharpest turns, making the wheels spin at the most different speeds. That, plus tires that are not evenly worn, makes the control module think that some form of slippage is occurring, thus engaging the clutch.

If you remove the front drive parts, the can may run as the TC clutch is engaged, but it can't run like that for very long before burning up. This may have happened, if you actually drove it like that very far.

 

Well, it has been a month now and NOTHING has changed! The jerks say they threw the parts away and seem to think they have done nothing wrong.

Could someone give me sort of an idea as to about how much the parts I need would cost me? I'm sure that I'll end up having to sell it but I want to find out my options first.

Thanks, guys!

 

Hi everyone:

I just read the guideline and it specifically does not allow any legal discussion in the forum. Otherwise, FTE may get into trouble. As it turned out, I was the first one who violated that rule in this thread, so I'm going to delete all legal discussions in this thread, starting with mine. Please don't be offended.