Doing a complete ATF drain?

[BrianL]

Arrg. Having to re-type this all again.

Help!
I have part of the fluid drained out but I'm 'stuck' and need to be able to drive it in the morning.

The cooler lines:
One line (call it line 1) goes from the top of the transmission, near the back of it, to the left side of the cooler.
One line (call it line 2) goes from the right side of the cooler to the bottom of the transmission, near the front of it, and right above where the pan mates to it.

Working with line 2, near the cooler, I disconnected the rubber hose portion from the steel hard line portion, and put the ~6" section of rubber hose into a jug. So, from cooler and into jug. I left the hard line section open.

When I ran the engine for no more than 1 second, quite a bit of fluid came out the hard line, making a mess, but none came out the rubber hose. What happened?
Are we sure the fluid returns from the cooler into the pan?
Do I just need to plug the hard line? Did it back pump somehow?

Thanks!

 

[ConfederateTyrant]

BrianL,
Sounds like you pulled the line going TO the cooler (line 2) instead of the line coming FROM the cooler (line 1). Try line 1 and you should be fine.

I just recently did a ATF drain and cooler line flush on a 2004 Sentra. For me the line on the top of the transmission (for you that would be line 1) is where fluid pumped from the rubber portion.

When I drained it via the pan plug, nearly a gallon of fluid came out, so I put in 4 quarts, and then I had my brother-in-law hold a gallon jug with the rubber portion in there while I let the engine idle and he let me know when it got nearly full. The fluid that was pumped into the jug was warm to touch, so I believe that if it pumped straight out of the pan the fluid should be rather cool. I don't think the gallon of fluid I added would have gotten that warm in a matter of two minutes, especially since most of the pan was dry, so little warm fluid to mix with.

 

[BrianL]

Thanks for answering. On the previous page, you said:

Quote:

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It was mentioned on here that when you pump through the cooler line, it pulls fluid from the pan, to the transmission internals, to the cooler, and out the line.

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According to that, line 2 should be the return line. If line 1 were, then it would be going straight from the pan to the cooler.

So going by that, it should go into the pan, then up through the trans internals, then out the top. I pulled the line that goes into the trans pan, which if it pumps the direction you said, is the return line (from cooler). I followed the line from the transmission several times, both by sight and by hand, to make sure I had that line.

 

[ConfederateTyrant]

Line 1 will pump out the same fluid out of the transmission, but it will not pump out the fluid from the cooler. If you use line 2, it gets the transmission internals (everything line 1 would get) AND cooler.

That is my understanding about the circulation, as for how well it works on every car, I cannot say. What makes me believe that is still true is how the gallon I pumped out made the jug warm, where as if I pumped out a gallon of fresh fluid, it should have the jug rather cool, logically speaking.

Also seems that everyone else's recommendations for draining, refilling, then flushing, appear to be in the same logic that the pan fluid goes up into the internals and out the cooler line.

 

[sky jumper]

Quote:

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When I ran the engine for no more than 1 second, quite a bit of fluid came out the hard line, making a mess, but none came out the rubber hose. What happened?

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you got the wrong line. you just learned the hard way that, when in doubt, you need to aim both lines into a drain jug (milk cartons w/ quart lines marked work best). every transmission I've flushed the cooler return line is the furthest to the driver side. you cannot tell by where it re-enters the transmission. just switch to the other line, and reconnect the 1st line.

overfill by 2 quarts, and pump 2 out. repeat until the capacity (including what you drained earlier) + 1 or 2 extra quarts has been replaced.

 

[BrianL]

Quote:

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Line 1 will pump out the same fluid out of the transmission, but it will not pump out the fluid from the cooler. If you use line 2, it gets the transmission internals (everything line 1 would get) AND cooler.

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I agree completely, and understood that.

But it seems mine is pumping in reverse, unless I just need to plug the hard line. But I dont want to try that until I know what's going to happen. Dont want to make another mess. Also wondering if I lost new or old fluid.

Here's a quick drawing I made:
http://img244.imageshack.us/img244/3598/transkk2.gif

 

[BrianL]

Quote:

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you got the wrong line. you just learned the hard way that, when in doubt, you need to aim both lines into a drain jug (milk cartons w/ quart lines marked work best). every transmission I've flushed the cooler return line is the furthest to the driver side. you cannot tell by where it re-enters the transmission. just switch to the other line, and reconnect the 1st line.

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I wasn't in doubt.

Also I did pull the line furthest from the drivers side.
Since you're saying you can't tell by where it enters the trans, are you saying it's possible that the fluid flow direction is the from the cooler, to the trans, down through the internals, into the pan, then from the pan to the cooler? The opposite direction of what we've stated.

 

[ConfederateTyrant]

BrianL,
Just to clarify, you said you used line 2 at first, correct? And that shot fluid out of the connector instead of the rubber part, correct? If both are true, then as sky jumper said, you just pulled the wrong line.

I re-read my post, the one you quoted, and I got the line numbers switched, my apologies. According to your picture, you'll want to pull line 1. As that is the one going to the top of the transmission. When you pull that, then fluid should come out of the rubber hose.

 

[sky jumper]

Quote:

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Quote:

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you got the wrong line. you just learned the hard way that, when in doubt, you need to aim both lines into a drain jug (milk cartons w/ quart lines marked work best). every transmission I've flushed the cooler return line is the furthest to the driver side. you cannot tell by where it re-enters the transmission. just switch to the other line, and reconnect the 1st line.

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I wasn't in doubt.

Also I did pull the line furthest from the drivers side.
Since you're saying you can't tell by where it enters the trans, are you saying it's possible that the fluid flow direction is the from the cooler, to the trans, down through the internals, into the pan, then from the pan to the cooler? The opposite direction of what we've stated.

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well, you should be in doubt, because you got the wrong line.

and it's not the line furthest FROM the drivers, it's the line furthest TO the driver's side (like I said). and no I'm not saying the flow is in reverse -- I'm saying that you cannot tell which line is which by looking at the outside of a transmission.

 

[sky jumper]

oh, and do NOT plug any lines.

 

[BrianL]

Quote:

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BrianL,
Just to clarify, you said you used line 2 at first, correct? And that shot fluid out of the connector instead of the rubber part, correct? If both are true, then as sky jumper said, you just pulled the wrong line.

I re-read my post, the one you quoted, and I got the line numbers switched, my apologies. According to your picture, you'll want to pull line 1. As that is the one going to the top of the transmission. When you pull that, then fluid should come out of the rubber hose.

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That doesn't make sense then. If that's true, we had the flow direction reversed, and also, that means that the fluid will be coming from the pan, to the cooler, then into my jug. So I'll only be draining the new fluid I've added to the pan.
In other words, because of where it's coming out (the line I left open and not in jug), it's flowing in a clockwise direction if looking at that picture.

Unless, even though the line (line 2/blue) is attached at the trans at the pan, it's not pulling fluid from the pan!? And line 1/red, even though it's attached to the trans behind the pan, and at the top of the trans, it's putting fluid in the pan!?
That couldn't be, could it?

Do you follow me?

 

[ConfederateTyrant]

I follow, hopefully I am not getting too confused and making idiot remarks. On my 1995 Mercury Grand Marquis, both of the transmission lines are about 1 inch apart, and are just above the pan, and when you pump through the cooler line, it pulls from the internals. So I may be just assuming with your car.

Here is one way to check, I think.

Pump out a gallon or so of fluid from the cooler line, and then drain the pan. You state that your pan drops out about 6 quarts, so if you get out nearly 6 quarts from the pan alone, then you'll know that the fluid is going from the transmission internals to the pan then to the cooler.

But if little fluid comes out of the pan, that would show that fluid is going from the pan into the internals and then out the cooler. As the return line is not supplying fluid into the pan, so therefore the pan should be fairly drained.

If anyone else can verify or clarify better methods, please chime in.

 

[sky jumper]

confed's suggestion will work. or just look at the fluid that comes out the cooler line - if you are pumping from the pan->cooler the fluid coming out the line will be clean. from pan->internals it will be dirty (or dirtier) for at least the first couple quarts (after which the internal mixing will cause it to look cleaner).

but really - it doesn't make any sense at all for it to be pumping from the pan to the cooler. think about it...
1) you have an oil strainer at the bottom of the valve body that dips into the pan -- why would it be there if fluid was pumping in the opposite direction? its much better to filter just before the fluid enters the internals, not on the way out.
2) you'd be pumping ultra hot fluid into the pan, where it would cool before going to the cooler. not an effective way to cool.
3) I'd also think it would be difficult to maintain line pressure with an oil cooler in the circuit before the internals. it would act like a liquid shock absorber.

triple check your lines to verify that you do indeed have line #2 per your diagram and that they didn't cross over somewhere.

 

[BrianL]

I had already checked several times, as mentioned above, to make sure I had line #2. I've checked half a dozen times now. The line that had fluid squirting out was coming from the bottom of the pan.

I went and bought some fuel line and hooked some to each hard line. So nothing was attached to the cooler at all. I ran the engine and sure enough fluid came sputtering then shooting out only the line I had previously had unhooked, which is line 2, which connects to the bottom of the transmission.

It only took probably 10 seconds to pump out 2 qts. Nothing came out of the other line.
The fluid looks fairly clear, though it has so much air mixed in it right now, so I'm sure it'll get cleaner, so I'm assuming that's part of the 3 quarts I added last night after draining the pan. FYI, only 3 qts came out of the pan. 6 qts is just what someone had said on a Frontier board.

So now I know how it's flowing, but I'm baffled as to how to do a flush. I thought about sticking the other line in new fluid sucking it in that way, but I read it wouldn't have enough suction to do that. Not sure how hard that would be to do by myself either.

 

[BrianL]

I took some photos.

Where fluid comes out the trans, front of trans, right above the pan:
http://img82.imageshack.us/img82/9715/lowerfrontout1sr6.jpg
http://img82.imageshack.us/img82/8296/lowerfrontout2cf7.jpg

Where it goes back in, rear or trans, near the top:
http://img155.imageshack.us/img155/5945/upperrearinzn3.jpg

Fluid I pumped out:
http://img82.imageshack.us/img82/9158/fluidpumpedre5.jpg
http://img167.imageshack.us/img167/1466/fluidpumped3sf6.jpg
http://img140.imageshack.us/img140/6986/fluidpumped2sy3.jpg
http://img291.imageshack.us/img291/7938/fluidpumped4wy7.jpg

New fluid:
http://img297.imageshack.us/img297/6086/fluidnewsu3.jpg


The fluid I pumped out is darker than new, but I'm guessing it's darkened from being mixed with the surface of the pan, and what came out of the transmission internals and into the pan when I ran the engine, which is about 20 seconds total now. The truck/fluid has 44K miles on it.

 

[sky jumper]

I still question this notion of "reverse" flow. it really doesn't make sense, and the fluid you pumped is definately darker.

ok - how does the fluid you pumped out compare to what you originally drained?? (do you still have it? or is it contaminated in a drain pan?) was that the original ATF w/ 47k miles on it? it is certainly possible that the original fluid is only slightly darkened, and would be consistent with your photos of the pumped fluid (and therefore the pumped fluid may not be coming from the pan). even more possible if the transmission has been serviced previously. (60k factory fluid in my nissan maxima was still red).

keep in mind - just because the line appears from the outside to go right to the pan doesn't mean it actually does - there could be all sorts of fluid chambers and such inside that you just can't see. and line #1 (the return line) could be lubricating something else before going back to the pan.

but if the ATF you first drained was obviously much darker than what you just pumped out (by obvious, I mean brown/burnt/nasty - otherwise there's not enough difference to make such a subjective call) then you might have a puzzle on your hands. it could be possible that your cooler is on some sort of parallel fluid path (i.e. not inline with the rest of the transmission internals) - you'd have to consult an FSM for your vehicle to confirm. you can download one from phatg20.com.

in any case, you'd still have to switch the other line to flush out the cooler itself (that is, unless you started the vehicle after the original drain/fill). good luck.

 

[unDummy]

Hottest ATF is at the torque converter. ATF exists the TC, via valve body plumbing, to the cooler. Notice how the hot ATF exit is closest the TC and VB(front of transmission). The cooler return line typically is a dump to the pan. But, OEM engineers sometimes screw up(inadequate lubrication or cooling in transmission). So, we take the cool ATF from the cooler and send that to the rear of the transmission to aid in lubrication(bearings, bushings, planetaries, output shaft). Typically wasted ATF exits the TC, goes to cooling(via whatever plumbing or VB controls)and exits cooler into the pan. Newer transmissions now use that wasted ATF to aid cooling and lubrication to certain 'hot' or 'dry' spots begging for more ATF. Anyone remember the Hondacura ATF jet recall???
Common performance mods to certain transmissions that waste ATF back to the pan is to increase ATF flow to known 'hot' or 'dry' areas of the transmission. This helps lube and cool, but without a bigger pump, might actually reduce the available flow for the TC and the cooler. I see that the Nissan JATCO has a win/win situation(actually more common in newer transmissions). Still maintain adequate flow through the cooler, without increasing pre-work ATF flow through the transmission. The post-work ATF leaving the cooler now has to work again prior to finding the pan. Double taxation anyone? Basically use the ATF flow capacity more efficiently vs. using a bigger pump and larger ATF flow circuits. Bigger pumps cost HP/MPG and require bigger sumps.

And a reminder for everyone, the ATF pickup is in the pan. Disconnect the cooler pressure plumbing will only create the pressured leak that will let you exchange the ATF. But, an open cooler hose will NEVER suck up ATF. I don't know where the rumour started saying other end will suck up new ATF. It doesn't! Suction is only in the pan at the ATF pickup. If you cut your garden hose in half, you have pressure at the water supply half of the garden hose, but there is NO vacuum at the handle or broken off half of the hose.

With a drain plug, a real good effective method is to just drain/refill once or twice a year and not to bother with cooler lines. They are simple. So, if you don't understand cooler line disconect, use the drainplug.

If you want to do a complete flush, you should start by doing a drain/refill on the pan. Then disconnect a pressure line, either before or after the cooler. Run engine until line burps. Top off, rerun, top off, rerun, until you use about 3 gallons of ATF. Some recommend quart or 1/2 gallon increments.
What I do, since vehicle is stationary, is drain and refill, overfill pan by ~1 gallon, disconnect cooler line & dump ~2 gallons, reconnect line, and final top off for an instant thorough ~3 gallon flush.

 

[ConfederateTyrant]

BrianL,
According to your pictures, the fluid you drained is much darker than the new fluid. Looks as if you are a little too worried about the flow, don't be. As you can see the consensus is still that you are getting fluid straight out of internals and not the "reverse" flow as you mention.

I would still suggests pumping out 1-2 quarts and then draining the pan. You should only get a quart or so from the pan, if you do then you know that the flow is going in the manner that we have described.

 

[BrianL]

Yes I realize the drain plug only method is preferred, but I've gone too long IMO and want to get it all flushed now. Also I'm selling the truck soon to someone I know, so I want to say it's been done, and not have them have to do several more partial changes in the very near future.

So are you agreeing that the line near the pan, that's pumping fluid to the cooler, is coming straight from the pan?

If so, even with your 1st method (disconnecting pressure line), I'll only be pumping out what I just put in, right? Or are you just saying to, similar to doing partial changes every so many miles, condense that into an hour, by using more fluid than needed? Which since it's always being mixed, this still wouldn't exchange all of the fluid, but perhaps that's my only choice.

I don't quite understand your 2nd method, or what it's doing with the fluid exchange.
What I do, since vehicle is stationary, is drain and refill, overfill pan by ~1 gallon, disconnect cooler line & dump ~2 gallons, reconnect line, and final top off for an instant thorough ~3 gallon flush.

 

[BrianL]

Quote:

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BrianL,
According to your pictures, the fluid you drained is much darker than the new fluid. Looks as if you are a little too worried about the flow, don't be. As you can see the consensus is still that you are getting fluid straight out of internals and not the "reverse" flow as you mention.

I would still suggests pumping out 1-2 quarts and then draining the pan. You should only get a quart or so from the pan, if you do then you know that the flow is going in the manner that we have described.

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It is a little darker than new, but again, I think it would be mixed a little when I ran the engine.?
I'm not disagreeing with you, but if what you're saying is true, that I'm not pulling new fluid, then the fact is that that connection just above the pan, as shown in the pic, is not picking up from the pan. Does anyone know this? Maybe unDummy was trying to say that in that long post, but my brain gave out.
I am 100% sure though that the fluid I'm pumping is coming from that connection down immediately above the pan mating surface.

As far as your 2nd paragraph, if I pumped 2 quarts, and then only got 1 quart from the pan drain, that would show that I'm pumping from the pan, as I have described. Or is that what you meant? Not sure what you meant by 'we', you/me or you/others.

BTW, to answer your post above that, I can't compare to the first 3 quarts I originally got from the pan, because it drained into a pan that had residual dirty motor oil in it.