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1998 Deville Base, 1999 Deville D'Elegance
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Discussion Starter #1
Although I am still searching to buy a 97-99 Deville D'Elegance, and I have test driven 5 so far, I am also concurrently researching information about these cars in advance of my purchase. I have used the "search" extensively on this site but still have a couple of questions I'd like to try and answer (with your help!):

Q1. I am having a tough time finding the transmission fill tube in the engine bay to check the transmission fluid. Can anyone tell me where this is located? I will also need to know this to drain (mityvac suction) and refill the transmission after I make my purchase. What kind of fluid is recommended?

I would like to improve the handling and eliminate some of the float in the suspension. So a few questions:

Q2. Is it possible to upgrade the springs - convert a D'Elegance with FE1 suspension to the springs from the Concours FE2/FE3 and use passive shocks from a company like Arnott? Also, are the anti-sway bars larger on the Concours version and can be installed on D'Elegance?

Q3. Which shocks give the most controlled ride (vs. the most plush ride)? It looks like people have used Strutmasters, Arnott, Gabriel (Autozone), Sears, Monroe but despite having read all the threads in the suspension section, I still have no idea which is best for handling/performance.

Thanks in advance,

Andrew
 

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99STS,2004 Jeep Liberty Renegade,98 Deville RIP
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Andrew, I cannot speak for the last two questions but for the first, on the 4T80E transmission, there is no fill tube as such, only a cap with a little dipstick on it, such as what you would have on a PS unit. In order to check the fluid level, the engine has to be hot and engine running. The transmission is a dry sump unit so it will not have any fluid showing when the engine is off. It is located under the Airbox and deep down on top of the Transmission itself. There is a weath of info about 'flushin' or whatever it is you plan on doing with your Mityvac Extractor. Since you are looking for a Deville in those years, here is a couple of other known issues to deal with, the Driver side seat heater will probably not work, and the rear knuckle bushings will probably be worn out causing a thunking noise at the rear, if you are planing on replacing suspension look at this first, it may save you some headache later.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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You cannot do the transmission fluid with a Mityvac or whatever. Don't even attempt it. If you're bound and determined to fool with the transmission, have a dealer do the job, including a refill with the new DEXRON-VI synthetic fluid - it's 100% backward-compatible with old DEXRON-III. Caddyshack is correct on the dry sump transmission 4T80E - you cannot check it with the engine off or fluid cool. Fill, hot, to halfway up the dipstick hashmark, engine running in P. There will be NO fluid on the dipstick with the engine off.

Maintain the recommended engine oil at halfway up the hashmarks also - the top mark is overfilled. Right out of the Factory Service manual.

Handling ???? Forget the D'Elegance and get a DTS. Cheaper in the long run than changing suspension parts that may or may not get you to heaven.....
 

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1998 Deville Base, 1999 Deville D'Elegance
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107 Posts
Discussion Starter #4
Caddyshack100 - Thanks very much for the useful information. Now I know where to check the transmission fluid (and how to do it). I had read about those pesky bearings - perhaps I should have new ones installed pro-actively when I do the suspension work - excellent suggestion.

Submariner409 - I appreciate your response but not sure I understand why only a dealer can change the transmission fluid? I have the right tool for the job - it is a vacuum extractor (this is a device with a large reservoir and a hand pump connected to a long tube and is used to literally suck the transmission fluid directly out of the transmission through the fill tube (without dropping the pan). I have used this tool on many other cars with great success. I would never "flush" the system at a Quick Lube as that is terrible for the transmission. However, I am strongly believe that regular changes of the transmission fluid is critical for long transmission life . . . Also, I will be purchasing a 97-99 vintage Deville and to the best of my knowledge, the DTS was not available those years.

So does anyone know if there were differences in the spring rates across the Deville model line from 97-99?

Thanks!

Andrew
 

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99STS,2004 Jeep Liberty Renegade,98 Deville RIP
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Andrew, two points,'first off, Sub is right on the mark, I did not realize what you were planning on doing and with what. The 4T80E is not a regular transmission per se, because you have to have it running to "evacuate" the fluid, the more you take out the less will be in the tranny and will in short order cause a burnt out Oil pump because you would be starving it of fluid. He was only trying to save you the expense of a burnt out Tranny. If you do a search on changing the fluid there are other ways to do it and will not cause any damage, nobody here wants to stop someone from doing the job themselves, hey we all got to learn but in this case, the lesson may be too expensive.

Secondly, its not the bearings that cause problems, although they do go, but rather the rubber bushings in the rear knuckles, the steel part is ok but the rubber wears out, to fix you have to replace the whole shooting match, at 1100 each side, I think someone has come up with a fix but I have not read up on it, keep up the search, you are on the right track.
 

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1998 Deville Base, 1999 Deville D'Elegance
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107 Posts
Discussion Starter #6
Thanks again, sounds like I need to do some more research before I plunge into the transmission fluid change . . . I'll also do some more research on the rubber bushings on the rear knuckles. I seem to recall reading a thread talking about the rear knuckles and I thought it was referencing issues with the bearings going bad. I'll do more investigation to learn more about the bushing problem - this is the first I've seen it mentioned although I'm sure it's been discussed plenty of times. I truly appreciate all the insights.

Andrew
 

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1998 Deville Base, 1999 Deville D'Elegance
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107 Posts
Discussion Starter #7
Okay, just figured I would post an update to this thread. I've done additional research and now realize that the fill cap on the transmission will not provide me with sufficient access to use the suction method to extract the transmission fluid (thanks Caddyshack100 and Submariner409). Having done my research, I am planning later today to attach a metal fitting and flexible hose to the transmission cooler return line (top connection on radiator) and run the engine with transmission in Park to pump out the old fluid. Then I am planning to refill with Dexron VI. Thanks again for all the help.

Andrew
 

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1998 Deville Base, 1999 Deville D'Elegance
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Discussion Starter #8
Just wanted to post a quick follow up to this thread for anyone who needs details on how to change the transmission fluid without dropping the pan.

To do this, I obtained a 6 foot length of hose and about 6" of metal tubing with a flanged end and lock nut in the correct size/shape to exactly fit the upper transmission line fitting on the radiator (driver's side top). I fit the hose onto the metal tube with flange and clamped it on. With the engine off, I disconnected the transmission cooler return line (upper radiator connection) and replaced with my makeshift drain line. I had a partner (my wife) start the engine while leaving the transmission in Park and allowed the transmission to pump the fluid out into a container (takes just a few minutes). I was able to pump out about 11 quarts this way. As soon as the flow of fluid started to sputter I had my wife immediately shut down the engine. I then reconnected the transmission return line and refilled the transmission with the new Dexron VI fluid.

So far, everything seems to be running well with the new synthetic fluid. I plan to repeat this process in a few months to finish the conversion to the new fluid since I didn't get all of the old stuff out the first time through.

Andrew
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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His exact procedure has been documented and used in here many times. JimD has also posted explicit instructions on how to do this, and it works. Simply replace the approximate amount pumped out, warm it up, check again, and go for a 20 minute drive.

IF the "old" fluid is still red or red/orange and sweet-smelling there is no need to go through the exchange process twice - DEXRON-VI is 100% compatible with -III, so you're just wasting money on a double-dilution process.

Remember that the 4T80E is a dry sump unit: there will be NO fluid on the stick with the engine OFF/cold. You must check and fill with the engine hot, idling in P (after shifting through all gears and R).
 
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