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Color Comparison: Automatic Transmission vs. Power Steering Fluid

4K views 49 replies 10 participants last post by  1997ThunderbirdLXV6 
#1 ·
Both fluids should be Mercon V. Power steering I changed soon after purchasing the car in late March; transmission I don't know when (if?) it was changed.

Note the difference in color.

My question: do non-Motorcraft fluids which meet or exceed Ford/Motorcraft specifications have the same color as the original Motorcraft fluid? Or do the specifications not include the color?

The transmission fluid is simply a more pale shade of red/orange (could that be the color of Mercon prior to Mercon V?).
It does not smell, and if you look at a drop hanging from the dipstick, it's entirely translucent (not milky, dark or opaque).

One way or another I want to replace the transmission fluid as soon as I find a place where I can do that. Just wondering if the color could be a clue as to what fluid is in there currently.
 
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Discussion starter · #18 ·
A thought...hear me out:

In a perfect world, I'd drain my transmission pan and torque converter and cooler lines. But I don't really have the space to do that right now. So why not do the same I did with my power steering?

With the steering, I simply siphoned out the reservoir, replaced the same amount of fluid with fresh Mercon V, and repeated this process after each drive until the quart of fluid was used up. The result is fluid that becomes gradually cleaner.

I could do the same with the transmission: siphon out through the dipstick tube (maybe what? 1-2 quarts per application?), replace with fresh fluid, and repeat.

Has anyone done this? How much can you get out of the pan with this method?
 
Discussion starter · #32 ·
@supergordo, @Kenz, I'm increasingly betting that this may be the original Mercon fluid. The original owner (23 years and about 29,000 miles) was very good to the car, but technically a transmission fluid change isn't until 30,000 miles (I realize you should consider mileage and time, but they may not have); the second owner (1,5 years and about 10,000 miles) only did oil changes.

Meanwhile, this siphoning exercise did help me make up my mind about how to proceed:

I will do the pan drop, filter change and torque converter drain. But before the pan drop, I will siphon out the fluid to minimize the mess.
I realize a lot of people recommend disconnecting a cooler line and then using the engine to pump the fluid from the pan out, but I just don't like that idea honestly. I'm not saying there's anything wrong about it; but personally I find the siphoning so much easier and cleaner, with essentially the same result.

I may not get all the fluid out. If I don't disconnect the cooler lines, I imagine that most of the fluid in the lines and in the radiator will remain. That being a fairly small amount (maybe 1-2 quarts?), I can live with it.
 
Discussion starter · #34 ·
You don't have to disconnect the cooler lines.
Well, I just re-read that old TSB...


...and now I'm wondering about that. The TSB states that any residual fluid in the lines can cause shudder, and to drain all fluid completely. Maybe they just wanted to make sure dealerships weren't cutting corners back then.

Questions:

Once the pan is lowered, if I simply disconnect the upper radiator line, will the fluid in the lines and radiator drain down to the pan (gravity plus air entering the line and radiator from the top)?

And a more general question: how exactly does fresh fluid get into the torque converter (and air out of it) after draining it? From what I'm seeing, the torque converter is an enclosed fixture with just one opening in the aft middle. But that opening is where the transmission shaft goes in. Sorry if this is a dumb question; just trying to understand the overall workings of it.
 
Discussion starter · #35 ·
When I read anywhere "deep pan", is that just in reference to the small, slightly deeper area in the middle (marked red in the picture) as opposed to an entirely flat pan? Or does "deep" refer to a pan which is deeper as a whole?
 
Discussion starter · #41 ·
But you do have to rig up a fitting and hose for the radiator, and run the car for 30 seconds.
And after 30 seconds it'll start pumping air?

I'm actually surprised that it would be so quick. Isn't the routing of the fluid this: pan > torque converter > cooler? In that case you'd think it would take much longer.
Or does it pump directly from the pan to the cooler?
 
Discussion starter · #43 ·
30 seconds should be safe. You don't want it pumping air.

Al
That's why I keep thinking...wouldn't it be best if I get a friend: one of us monitors the color of the fluid coming out of the cooler line; the other pours fresh fluid into the dipstick tube? This way there's no risk of the transmission to pump air and/or run dry. And once the color at the cooler line turns to bright red, you stop the engine.
 
Discussion starter · #45 ·
In the transmission fluid change instructions on crownvic.net, there's the following paragraph:

"Disconnect the battery, unplug the PCM from the harness, or remove the PCM "KAM" fuse while the converter is draining to re-set the adaptive shift strategies in the PCM for the transmission. This is VERY IMPORTANT !"

I haven't read any such thing on TCCoA. Any thoughts?


For the cooler lines, I see at the radiator there's one at the top and one at the bottom. Which one is fluid going to the radiator, and which one is the return line to the transmission?
 
Discussion starter · #50 ·
So to bring this thread to a close, as always, thanks to everyone for your expeditious answers and solid advice.

Today I went ahead and did a "limited" transmission service. Specifically I did not drop the pan and change the filter. I do not have any stands/ramps currently and no place to store them if I bought a pair. My drive one wheel up a curb technique worked great for an oil change, but it doesn't provide enough space to access the transmission. Yup, this is a budget operation. Given the car's mileage (43,000) and state of the fluid (no dullness or visible solid matter in the fluid whatsoever), I'm actually not terribly concerned about the filter, though it'll still be on my to-do list for another time (then also including the installation of a supplemental cooler).


So what did I do?

- First I siphoned the fluid from the pan. This produced 3.5 quarts. I refilled immediately with fresh fluid.

- Then I disconnected one of the cooler lines and connected it to a transparent tube, prepared with several empty containers to catch fluid. Meanwhile my friend was set up at the dipstick tube with a funnel plus ready to pour quarts of fresh fluid.
I started the engine and collected the old fluid while my friend poured fresh. I monitored for changes in fluid color. The old fluid's orange-brown turned to red after 8-9 quarts or so.

- Finally I reconnected the cooler line, checked and adjusted the fluid level cold, drove the car, checked fluid level hot, etc. Ultimately a grand total of 13.5 quarts fresh fluid went in.


I realize this may not be the full service most of you recommended (pan drop, T/C drain, etc.). But given my limited possibilities right now (you can only do so much downtown on the side of the street), I think this was a good compromise. I'm glad (most of) the old fluid is out.

For anyone wanting to do this, know that the person pouring the fresh fluid has to be very quick to keep up with the old fluid coming out. Another observation: removing the fan is very easy, and it makes the cooler lines much more accessible.


Initial observations from a quick drive: I would say slightly smoother; this includes smoother engagement when shifting between R and D. Absolutely no torque converter shudder; and I did go to the (slight uphill) stretches where I used to be able to reproduce the shudder.
This may be unrelated, but the couple of times I started the engine after the fluid change, it started more quickly than what I'm used to.
 
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