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Transmission Fluid Change


Spurlee

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All:

I changed my radiator last weekend and neglected to reattach the lower transmission cooling line :blink:

It pumped out half a quart or so before I noticed, then I ran out of time and just left the line disconnected until I can get to the car again. I got to thinking that maybe I should go ahead and change (not flush) the transmission fluid. Looking here, I found the following commentary:

Are you willing to change the fluid yourself for the cost of a case of fluid without even getting under the car?

Break into the plumbing that returns the fluid from the radiator back to the transmission. Use a length of flexible hose connected to the radiator fitting and into a 3 or 5 gallon bucket.

Fire up the engine at idle and the tranny pump will do the rest. Shut off the engine as soon as the fluid stops flowing.

This does not address your filter (screen) concern, but it will keep several hundred dollars in your pocket and you will know all the fluid has been replaced. Plus you have remained miles away from someone's flushing machine.

That's basically where I am right now...unless someone has contrary advice I think I'll just let her pump dry and refill.

Oh, what's the recommended fluid and quantity?

Thanks!

Scott

1996 El Dorado

2006 STS

2000 Corvette

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Dexron-III is spec'd. for my '98 and probably your model also. Service Manual says the dry capacity (as in after overhaul) is 15 quarts.

You really want to pay attention to the fluid level when the engine coolant (and therefore the tranny fluid) is at operating temperature. Bring the fluid level to the middle of the hash marks in the HOT section of the dipstick. If you overfill, suck some out with a turkey baster.

Jim

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I need to change my pan gasket soon, maybe I will drain the system this way. Very interesting. Are we all sure that this method won't do any damage to the clutches or babbet (or metallic) bearings? Thanks

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I would keep adding fluid as the old is being pumped out.

Why? It just seems to me that it wouldnt be good for the trans., pump ect. to be run out of fluid. I dont know for sure running dry will hurt it but I would find out before doing it.

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I need to change my pan gasket soon, maybe I will drain the system this way. Very interesting. Are we all sure that this method won't do any damage to the clutches or babbet (or metallic) bearings? Thanks

Mike,

I remember the Guru told there would be no damage if you turn the engine off as soon as it stops flowing. I am going to change my ATF this way too when I replace th ecooling lines. I never had a chance to replace ALL the volume of ATF.

The saddest thing in life is wasted talent

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Those are my words up there in the first post; I have done the procedure several times and killing the engine as soon as the fluid flow stops is what protects the tranny from being damaged (although the possibility of damage is remote because you are in Park or nuetral).

I would absolutely drain one this way if the bottom had to be opened for any reason.

In fact, I have a fitting in my tool box that goes into the top radiator plumbing for the quick disconnect type cooler line fittings.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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Thanks Jim, if you don't mind, what line did you break into? The Left bottom or top line? I think the Right lines are engne oil cooler lines, and the LEFT are tranny cooler lines, right?

My pan gasket is leaking like a sieve. The leak on my new driveway is the SHAPE of the PAN :blink: The tranny fluid was changed before I bought my car, they used the old gasket which is standard procedure I believe. I have a new gasket (not cheap) and I plan to use RTV on the bolt threads and possibly buy new washers for the tiny bolts. I think the washers are suppose to have a small bevel in them, but I might be wrong. Anyway, I have always hated dropping tranny pans its a messy job. I even have a huge catch attachment for my drain pan for that purpose, but draining the fluid this way will be more thorough.

Remember when our member blunted had his tranny fluid changed? It was done by Richters in New Jersey... They didnt know there was a side pan drain.... Guess where my tranny was drained.....Richters in NJ.....so I can be reasonably certain that the side pan wasn't drained.... :rolleyes::lol:

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Jim:

Since you've done this before and seem confident - I'll give it a try. My lower transmission hose is disconnected now, I'll run it until it stops and turn off the engine. Refill with Dextron III up to 15 Qts (!).

Seems like a very handy solution.

15 quarts - wow. I had no idea! I'll have to shop around for a good price.

Scott

1996 El Dorado

2006 STS

2000 Corvette

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Thanks Jim, if you don't mind, what line did you break into? The Left bottom or top line? I think the Right lines are engne oil cooler lines, and the LEFT are tranny cooler lines, right?

My pan gasket is leaking like a sieve. The leak on my new driveway is the SHAPE of the PAN :blink: The tranny fluid was changed before I bought my car, they used the old gasket which is standard procedure I believe. I have a new gasket (not cheap) and I plan to use RTV on the bolt threads and possibly buy new washers for the tiny bolts. I think the washers are suppose to have a small bevel in them, but I might be wrong. Anyway, I have always hated dropping tranny pans its a messy job. I even have a huge catch attachment for my drain pan for that purpose, but draining the fluid this way will be more thorough.

Remember when our member blunted had his tranny fluid changed? It was done by Richters in New Jersey... They didnt know there was a side pan drain.... Guess where my tranny was drained.....Richters in NJ.....so I can be reasonably certain that the side pan wasn't drained.... :rolleyes::lol:

I believe all 4T80-E's are plumbed the same way, but sure as I say that someone will have one that is different. I open the top line on the LH side of the radiator, remove the adapter fitting from the radiator tank and install my 90 degree elbow in the tank, clamp on a piece of flex hose and run the hose over the fender to a bucket at the driver's door. So I am there with one hand on the key and one hand holding the hose.

For those with GM quick disconnect fittings, but careful to not lose the little clip or the small - small O ring.

Opening the bottom line allows the fluid that is in the radiator side tank to drain out via gravity and you are right back with a big mess; just in a different place.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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I believe all 4T80-E's are plumbed the same way, but sure as I say that someone will have one that is different. I open the top line on the LH side of the radiator, remove the adapter fitting from the radiator tank and install my 90 degree elbow in the tank, clamp on a piece of flex hose and run the hose over the fender to a bucket at the driver's door. So I am there with one hand on the key and one hand holding the hose.

For those with GM quick disconnect fittings, but careful to not lose the little clip or the small - small O ring.

Opening the bottom line allows the fluid that is in the radiator side tank to drain out via gravity and you are right back with a big mess; just in a different place.

Hmmmm...let me see if I can retrofit your procedure to match my situation.

It seems that the pump pushes fluid up through the tank to the top fitting. Since my LOWER line is already disconnected and the radiator side tank has already drained on my floor, I can connect a flex hose to the LOWER line and it should pump nicely to a disposal container.

Have I got it?

Scott

1996 El Dorado

2006 STS

2000 Corvette

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Thanks Jim... There is NO danger of backing out the adaptor fitting from the radiator tank? Do you think rather than removing the fitting I can get a fitting that screws into to radiator tank after the tubing is removed?

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Thanks Jim... There is NO danger of backing out the adaptor fitting from the radiator tank? Do you think rather than removing the fitting I can get a fitting that screws into to radiator tank after the tubing is removed?

I'd go that way...fitting flex hose to the adapter rather than the radiator itself safer than potentially damaging the radiator threads themselves.

My two cents.

Scott

1996 El Dorado

2006 STS

2000 Corvette

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I believe all 4T80-E's are plumbed the same way, but sure as I say that someone will have one that is different. I open the top line on the LH side of the radiator, remove the adapter fitting from the radiator tank and install my 90 degree elbow in the tank, clamp on a piece of flex hose and run the hose over the fender to a bucket at the driver's door. So I am there with one hand on the key and one hand holding the hose.

For those with GM quick disconnect fittings, but careful to not lose the little clip or the small - small O ring.

Opening the bottom line allows the fluid that is in the radiator side tank to drain out via gravity and you are right back with a big mess; just in a different place.

Hmmmm...let me see if I can retrofit your procedure to match my situation.

It seems that the pump pushes fluid up through the tank to the top fitting. Since my LOWER line is already disconnected and the radiator side tank has already drained on my floor, I can connect a flex hose to the LOWER line and it should pump nicely to a disposal container.

Have I got it?

You are 100% correct on the flow. However, if you have a quick disconnect on your plumbing, you will have to engineer the flex hose - to metal pipe interface. Should be doable.

It's starting to sound like '98 was the first year for quick disconnect tranny plumbing.

Either way, whatever it takes to make a reasonably tight seal at the top of the tank is all you need. Since the bucket end of your flex hose is open, the will be little to zero reason for a pressure leak where the flex hose is attached.

This is the adapter I fabricated for my '98.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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I too remember our guru saying that no damage would be done idling in neutral. However, I would drop the pan IN ADDITION to this proceedure so you can wipe out the pan and all the sludge off the magnet. There is a lot of sludge on that magnet after 100K.

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OK guys, I'm armed, dangerous and ready to battle with the transmission this weekend.

Since January I have almost $2,000 in maintenance items on this car (A/C, WaterPump, Alternator, Radiator, Tensioner, Idler, Hoses, Serp. Belt, Rotors/Pads, etc., etc.). And that includes only $500 in shop labor (A/C and Alternator). That's thanks to the people on this site and Rock Auto.

Onward!

Scott

Scott

1996 El Dorado

2006 STS

2000 Corvette

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