An alternative method to flushing transmission fluid! Is it safe?

[masterzelda]

I have a 1994 Cadillac Seville STS with over 172K miles on it; and it still has the original engine, and transmission. I bought it with over 171K miles; and the engine, and transmission run fine. However; the transmission fluid is clearly broken down, and is in desperate need of changing! I cannot get a shop to do it; because they claim that the high pressure flushing method they use to change the fluid could damage the old transmission.

I have considered doing a low-pressure change myself in the same fashion that I would change the engine oil; but I know that would leave a great deal of that dirty old fluid in there! A friend who knows cars told me that if I disconnect the inlet hose from the transmission oil cooler, and let the engine idle; that the engine will flush out most of the bad fluid without applying harmful pressure to the transmission.

This would of course be a two-man job; because someone would have to watch the fluid draining process closely; and signal the other man sitting behind the wheel to turn the engine off immediately after the fluid stops draining to avoid burning out the transmission. Sounds like a pretty clever idea; but it could also turn out to be a game of Russian Roulette with my transmission! Any thoughts?

[Ranger]

That method works well and is often recommended here. No Russian roulette. You won't do any damage as long as you leave it in neutral. Put a clear vinyl hoes on the pipe and feed it into a bucket. Pour in fresh fluid as the old is being pumped out until it runs clear. I would still recommend dropping the pan and cleaning it and the magnet.

[masterzelda]

If it isn't a case of "Russian Roulette;" then I suppose I can do it as a one man job! The only issue I see would be dropping the pan. I guess I should do that before flushing the old fluid out. I will use alot more fluid that way; but if it will get more life out of the transmission, it is well worth it! Thanks for the tip!

[Talamant3z]

how can u tell if the fluid is broken down? smell?

[submariner409]

Transmission fluid is normally clear red and slightly sweet-smelling. Fluid that is noticeably brown and/or smoke or acrid -smelling should be changed.

Transmission fluid is not subject to the same contamination as motor oil, so if a transmission is not used for heavy trailer towing or constant drag racing the fluid will last for AT LEAST 100,000 miles, often a lot more.

[Ranger]

When you drop the pan, don't forget to pull the hidden drain plug under the side cover. I believe it is the bolt between the screens under the wire loom.

[masterzelda]

One more question. Should I drain as much as the old fluid as possible; and clean the pan, and change the filter before doing the flush? The fluid is very dark and grey. It smells more like ash than a sweet substance. It also does not feel very slick. I have cooked with cheap cooking oils that were better lubricants!

One more thing! The previous owner likes to race. He has two race cars he pretty much built from the chassy up; and I know he drives over 100 mph frequently on regular roadways! It is safe to say my Seville has been pushed to the limit!

[Ranger]

Yes, drain, clean the pan and screens, then flush. I wouldn't worry about being pushed to the limit.

[JimD]

Originally Posted by masterzelda

One more question. Should I drain as much as the old fluid as possible; and clean the pan, and change the filter before doing the flush?

You seem determined to make this simple procedure as difficult as possible. Cleaning the pan and the magnet will make you feel good, but the benefit to the transaxle is marginal. The filter you will have access to is little more effective than porch screen material.

Consider this approach.
Open the return line plumbing between the radiator side tank and the transaxle (should be the top fitting).

Engineer a fitting to attach six to eight feet of flexible hose into the radiator side tank.

Point the open end of the hose into a four gallon bucket placed at the LF door where you can observe the fluid flow while sitting in the driver's seat.

Fire up the engine at idle with the transaxle in PARK.

The instant the fluid flow stops, shut the engine OFF.

Optional: Now you can R & R the pan and do the interior clean up.

Install the original plumbing to the radiator side tank.

Install 11 quarts of DEXRON III or DEXRON VI; I recommend VI, but it is expensive.

Correct the fluid level as required with the engine at normal operating temperature at idle with the transaxle in PARK.

Done. And if you skip the optional bit, there is no need to have DEXRON dripping off your elbows!!

[Ranger]

On second thought, I like Jim's idea better. Pump it down first, THEN drop the pan. Much less of a mess.

[mysedan]

couple of questions here. (I am waiting on my helms to arrive...but it wont be for a few days and the work is calling me back, so maintanance needs to get done now)

How many quarts of trans fluid will I need? (95 sedan deville)

what EXACTLY is this bucket method business? I am doing this solely on my own so easier is much better.

I am only planning on doing a fluid change...not dropping the pan or anything...

where is my hose located at?

Can I just pop off the trans cooler line and pump it out that way? Also can I use just a hose clamp to attach the clear hose to the cooler line?

I floored it for the first time the other day and noticed I didnt get a nice firm crisp shift (and having been around GM trannys long enough...I expected something a LIL better than what I got....no I HAVENT inspected the fluid yet but I have a feeling it hasnt been done in some time)

I dont tend to push on the ole girl much if at all....its a big car and I have this thing about NOT liking to be pulled over or have some moron pull out in front of me with a 4,000lb car that stops lil better than a tank.

But I would like to get some of my maintanance done

thanks in advance for any help

[Ranger]

How many quarts of trans fluid will I need? (95 sedan deville)

The owners manual should tell you how many quarts the 4T60E holds. I forget.

what EXACTLY is this bucket method business?

Jim explained it in post #9. Basically you use the trans pump to pump out the old as you pour in the new.

where is my hose located at?

The trans fluid lines are in the right side radiator side tank.

Can I just pop off the trans cooler line and pump it out that way?

Yes, that's what he is talking about.

[JimD]

Originally Posted by Ranger

....Jim explained it in post #9. Basically you use the trans pump to pump out the old as you pour in the new.

No need to "pour in the new". That would be a waste of fresh fluid.

No offense intended, Larry.

Pump that sucker dry at idle in PARK then kill the engine. Fill the transaxle with one or two quarts less than the specified volume and adjust the level as necessary.

[Ranger]

None taken Jim. I just recall someone once mention that and did it til it started to run clear, but I see your point and fully agree.