Changing transmission fluid?

[brade07]

I've read how-to's on changing the fluid in the CD4E, and some say to unscrew the drain plug to drain it and others say take of the bottom hose going to the cooler. I wanted to know if ours transmissions actually have a drain plug, and also if they do, do i drain all the fluid out?

[BrantlyJ]

use the drain plug on the bottom of the tranny. It will drain about 4 qts.

[brade07]

Alrite just wasnt for sure
Thanks

[unisys12]

The how-to's that refer to removing one of the hoses at the cooler are probably pointing you in the direction of how to do a system flush. That is the only difference. They all basically have you unhook the lines at the cooler. Put the cooler input into a clean empty bucket and the cooler output into a bucket of clean fresh fluid. Most of the one's I have read say to only put 4 quarts of fluid in at a time. You then turn your car on and let it idle. The tranny's pump will pump the fluid for you. Stop the engine just before the fluid runs out of the input bucket. We don't want any air in the tranny!! Repeat until the the fluid begins to come out into the empty bucket.

Also, when doing this, it would be a real waste if you didn't flush your cooler too! Lots of debris can accumulate in the cooler. You can by cans of stuff that will do this at some places, like NAPA (I've seen them last year). You attach whatever you are going to flush the cooler with to the "output" of the cooler and force it through the cooler and out of the input. This flushes the cooler in a reverse flow fashion, which will clean the cooler much better than if you flushed in it's normal flow direction.

I hope all that made sense.

[BrantlyJ]

Originally posted by: unisys12
The how-to's that refer to removing one of the hoses at the cooler are probably pointing you in the direction of how to do a system flush. That is the only difference. They all basically have you unhook the lines at the cooler. Put the cooler input into a clean empty bucket and the cooler output into a bucket of clean fresh fluid. Most of the one's I have read say to only put 4 quarts of fluid in at a time. You then turn your car on and let it idle. The tranny's pump will pump the fluid for you. Stop the engine just before the fluid runs out of the input bucket. We don't want any air in the tranny!! Repeat until the the fluid begins to come out into the empty bucket.

Also, when doing this, it would be a real waste if you didn't flush your cooler too! Lots of debris can accumulate in the cooler. You can by cans of stuff that will do this at some places, like NAPA (I've seen them last year). You attach whatever you are going to flush the cooler with to the "output" of the cooler and force it through the cooler and out of the input. This flushes the cooler in a reverse flow fashion, which will clean the cooler much better than if you flushed in it's normal flow direction.

I hope all that made sense.

actually this is incorrect info. The tranny will not draw fluid from the bucket. The pick-up is more than likely in the oil pan.

[unisys12]

Originally posted by: BrantlyJ

Originally posted by: unisys12
The how-to's that refer to removing one of the hoses at the cooler are probably pointing you in the direction of how to do a system flush. That is the only difference. They all basically have you unhook the lines at the cooler. Put the cooler input into a clean empty bucket and the cooler output into a bucket of clean fresh fluid. Most of the one's I have read say to only put 4 quarts of fluid in at a time. You then turn your car on and let it idle. The tranny's pump will pump the fluid for you. Stop the engine just before the fluid runs out of the input bucket. We don't want any air in the tranny!! Repeat until the the fluid begins to come out into the empty bucket.

Also, when doing this, it would be a real waste if you didn't flush your cooler too! Lots of debris can accumulate in the cooler. You can by cans of stuff that will do this at some places, like NAPA (I've seen them last year). You attach whatever you are going to flush the cooler with to the "output" of the cooler and force it through the cooler and out of the input. This flushes the cooler in a reverse flow fashion, which will clean the cooler much better than if you flushed in it's normal flow direction.

I hope all that made sense.

actually this is incorrect info. The tranny will not draw fluid from the bucket. The pick-up is more than likely in the oil pan.

Ok... "Maybe" you are right, in that it wont draw fluid from the bucket. But since there is no pick-up in the "oil pan", your theory is not going to work either. How do you think shops connect a power flush machine to an ATX to perform a flush? I'll give you a hint, they don't remove the valve body cover ("oil pan"). Also, given the number of people out there that have done this; not only with their ATX, but power steering system as well, it's a darn shame.... since they were all wrong too.

:biggrin:

[BrantlyJ]

well I must have the only ATX that that doesn't draw fluid from the cooler line. because I did a flush 10,000 miles ago and not one drop was drawn into the tranny from the cooler outlet line.

I don't have the schematic of the pump circuit but with my extensive knowledge of hydraulic systems I can take a very educated guess that the cooler circuit is last in line. And that the fluid is "pushed" from inlet to outlet. If it was first in line I could see how it would draw fluid from the outlet of the cooler but in my entire career of designing hydraulic circuits I have never see a cooler on the suction side of a pump.

Again I haven't experienced a power flush tranny fluid machine but I would guess to say that as the old fluid is pumped out of the inlet line that new fluid is pumped into the cooler outlet by a pump in the flushing machine.

If your method works I would love to see a video of it in action.

[unisys12]

Well, I think that most people that know me, or of me, know that I am not one to back down when I am wrong. But I will when I am right. Weird, yeah I know!

So I'll tell ya what. Here is a pic of the CD4E Fluid Schematic and we will find out, one way or the other. If I am wrong, then I will admit to that. If I am right, then I will not post again.


http://atxprobes.com/oilcd4e.jpg

So from this, we know that the pressure going into the cooler is regulated to 110psi Max. Ok, that really doesn't mean anything. Or does it?

Since the pressure, feeding the cooler, is regulated at 110 psi Max and the Main Regulator controls the pressure to the TCC Regulator, then can we say that the two are sorta connected?

Also, the cooler flow seems to be controlled by the same circuit, so...

Would this mean that the fluid pressure coming into the cooler is regulated at the same rate coming into the cooler as it is coming out?

Why do I ask this??

I seems to me that the filter/sump portion, which is really what is in question here, is controlled by the same circuit.

Now! If the sump for the CD4E is located in the case of the tranny, on the opposite side of the filter, then shouldn't it pull at the same pressure as it is pushing?

HOnestly, I find this to be one of the more interesting debts that I have had in a long time. So please, do not think that I am trying to be an a$$ or something. I'm not. :biggrin:

[BrantlyJ]

That's an interesting pic you threw up there.

I'm very surprized to see that the filter is on the suction side of the pump. But from what I hear the filter is no more than a strainer anyways so not a big deal.

What we want to note here is the inlet to the pump is indicated by a symbol that represents a tank, or sump in this case. In hydraulic terms that picture represents a holdign area for fluid. So that would indicate that the pump will draw fluid from the sump. It is not fed from another circuit. The question here is where is the inlet for the pump. I haven't seen the inside of our tranny but a good guess would be near the lowest point in the case.

According to the pic, the cooler is fed from the Torque converter. This would make sense because the TC probably generates the most heat. If you look at the output of the cooler line it says it goes to "rear lube". I would guess it's feeding some bearing and the output just pukes into the case. This is probably also why the coolor output line will not draw fluid out of a bucket. It would need to be imersed in the sump for that to happen.

Line pressures are irrelevant to this discussion because as you can see from the legend that each color represents a different circuit.

haha, interesting twist from going how to change your fluid to an in depth look at the pump circuits. :beer:

[unisys12]

Yeah, I see your point. I think I am going to do some research on the Pump and get back with you on that one. I will give it to you though... you are probably right. :banghead:

P.S. That pic is from the A-Teams website. No, not The A-Team, but the A-TEAM (https://http://atxprobes.com/cd4e.html)