Is this transmission cooling setup normal/acceptable

Discussion in 'Transmissions' started by BhutJolokia, Aug 31, 2020.

  1. thegawd

    thegawd OBS Enthusiast

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    Alison probably said no fricken way to an internal cooler knowing how well dodge builds everything, with the exception to the cummings trucks... which are nice but do rot as all dodge, ram and Chryslers do. My work truck is a fully deleated and fully supped up 2008 Ram 6.7 turbo Cummings. I'm a cabinet maker and haul some serious loads.

    If a cooler or a cooler line gets plugged it will puke out all the tranny fluid through the top rubber breather overflow line, an overfilled tranny will also puke out the excess fluid.

    Al
     
    Last edited: Sep 16, 2020 at 1:09 PM
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  2. Pinger

    Pinger I'm Awesome

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  3. Schurkey

    Schurkey I'm Awesome

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    Hard to know where to start.

    First off, 203 degrees on modern trans fluid is nothing to be concerned with. I wouldn't waste the mental energy to give a shit, never mind spending time, money, effort, and enthusiasm to "fix" what isn't a problem. GM doesn't turn on the electric radiator fans until 220+ degrees, so the trans fluid cooled by the radiator is going to be ~200 degrees on my wrong-wheel-drive cars.

    Second, there's three ways to "add" an auxiliary trans cooler. Before the in-radiator cooler;
    After the in-radiator cooler; and
    Instead of the in-radiator cooler.

    Which way is best depends on the circumstances. Around here, I'd want the radiator to heat the fluid before it's returned to the transmission. (I've never bothered to see if that's how the aux. coolers of my trucks are plumbed.)


    5.5 liters of fluid is nowhere near enough fluid to flush the trans with. IF (big IF) you already drained the pan and installed a fresh filter, and then refilled the pan, 5.5 additional liters MIGHT be enough to flush the converter with. Probably not.

    I just finished changing fluid on my '03 Trailblazer 4L60E two days ago. I dropped the trans-to-cooler tube at the radiator, (because it was easier than the cooler-to-trans tube) pushed it into a two-foot rubber hose leading to a BIG drain pan, and started the engine. As soon as the fluid coming out of the hose stopped gushing and began trickling, I knew the pan was nearly empty--the filter was sucking air. This does not empty the torque converter, it empties the pan.

    Remove pan, change filter, clean pan and magnet and pan gasket surface area of the case, install pan with new gasket.

    I put 8 quarts of Dex/Merc ("Dexron III compatible") down the dipstick tube (Usually I only install 5 quarts, but this is a deep pan), opened five more quarts, and started the engine. I dumped fluid down the dipstick tube as fast as I could, until the fluid coming out the rubber hose into the drain pan was bright red. Shut off engine, reconnect cooler tube, start engine and top off fluid as needed. I went through about 14 quarts (more than 13 liters) altogether, but now all the fluid in the trans is fresh except the little bit trapped in the clutch piston housings, servo, accumulators, etc.

    I could have disconnected both cooler tubes, regulated my compressed air supply down to ~30 psi, and back-flushed the cooler with compressed air--but I didn't. There was no debris in the pan other than some fuzz on the magnet, so I figured there'd be no debris in the cooler, either.
     
    Last edited: Sep 17, 2020 at 12:04 AM
  4. Pinger

    Pinger I'm Awesome

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    Thanks Schurkey, lots of useful info there.

    What about a variation on the theme.

    Drain pan (via drain plug or suction via dipstick tube), remove pan and re-fit with new filter and gasket.
    Add circa 5.5 to 6 litres via dipstick tube.
    Remove cooler line and place in drain tray, start engine, work through all gears (park to D1 and back again) and when flow from cooler line ceases, stop. This would allow displacement of old oil in pistons etc into pan where it can be picked up by pump and pushed towards cooler line and, partial flushing of TC.
    Drain (via drain plug or suction via dipstick tube) remaining oil in pan (optional).
    Add circa 7.3 litres of oil via dipstick tube, start engine and when fresh oil seen at cooler line, stop. This would flush last of old oil out of TC.
    Reconnect cooler line and top up oil to mark on dipstick.
    At a suitable point in the above, the cooler can be drained and refilled.
    Viable?
     
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  5. El Tigre

    El Tigre I'm Awesome

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    Only problem is the fluid normally travelling back to transmission is what lubricates the internal bushings of the transmission. Interrupt it's flow while forcing shifts through the valve body manually at your own risk,ad/or peril.
     
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  6. Pinger

    Pinger I'm Awesome

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    Fair point.
    So to flush the pistons etc, I'd need to do that before disconnecting the cooler lines, let that oil fall back into the pan then select park and then continue with disconnecting cooler line and let the oil that has landed in the pan be the first through to flush the TC?

    Entire process would now be:

    Drain pan (via drain plug or suction via dipstick tube), remove pan and re-fit with new filter and gasket.
    Add circa 5.5 to 6 litres via dipstick tube.
    Start engine and work through all gears (park to D1 and back again) This would allow displacement of old oil in pistons etc into pan (where it can be picked up by pump and pushed towards cooler line and, partial flushing of TC in the next step).
    Remove cooler line and place in drain tray, start engine and when flow from cooler line ceases, stop.
    Drain (via drain plug or suction via dipstick tube) remaining oil in pan (optional).
    Add circa 7.3 litres of oil via dipstick tube, start engine and when fresh oil seen at cooler line, stop. This would flush last of old oil out of TC.
    Reconnect cooler line and top up oil to mark on dipstick.
    At a suitable point in the above, the cooler can be drained and refilled.

    Is 5.5 to 6 litres added for initial flush more than required to flush gearbox internals?
     
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  7. Schurkey

    Schurkey I'm Awesome

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    If you insist on running through the gears while doing the trans fluid change, KEEP YOUR FOOT ON THE BRAKE. If the output shaft isn't turning, and the gears aren't spinning...nothing back there needs lube.

    "I" wouldn't--and didn't--bother to flush the servos, accumulators, clutch piston housings, etc. It's just not that important. There isn't a lot of fluid trapped there. AND, you'd have to spin the output shaft high enough to engage Overdrive, in order to flush the Overdrive fluid circuit. This is unreasonable, because with the output shaft spinning at ~50 mph, you've got to have lube in the geartrain. I change the fluid in the pan, I flush fresh fluid through the converter, and maybe flush fresh fluid through the cooler(s), and call it "good enough".

    Given that most folks only change the fluid in the pan, and nowhere else including not changing the fluid in the torque converter...you're already going "above and beyond". Plenty of shops "exchange" fluid without ever dropping the damn pan--they DON'T BOTHER TO CHANGE THE FILTER or remove debris from the pan and magnet!
     
    Last edited: Sep 17, 2020 at 4:53 PM
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  8. El Tigre

    El Tigre I'm Awesome

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    If you have a drain plug,you could simply drain/refill with new fluid. Drive for a week,and repeat as many times as you like without worry as the overall condition of the fluid is only going to improve until you decide to drop the pan,replace filter,and refill for the final time. I made a device to exchange trans fluid once,and it worked well. Using two (half gallon) mason jar with two AN-06 ports in each lid. Each having a 1'2" tube running to the bottom,and the other ports connected to each other. One (tubed) port was connected to trans return line from cooler,and the second jar was filled with new fluid,and connected to hose that actually returned to trans. Clean pan,filter,fluid already installed. Start vehicle,and watch Jar #1 fill with fluid,and displace air into Jar #2 forcing new fluid back into trans. Shutting off engine prior to Jar #1 becoming totally filled. Discard fluid from Jar #1,and refill Jar #2 with fresh fluid. Each time you will see the fluid in Jar #1 become cleaner,and clearer. Until it approximates the color of the new fluid in the jar right beside it. This method probably uses more fluid,but there's no need to keep checking the level either. As the same amount of fluid coming out is continually going back it. I use/recommend Dexron VI,and amazon has it for about $25/gallon. Transmissions are not cheap,and clean fluid goes a long way to helping them last,and last...
     
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  9. Pinger

    Pinger I'm Awesome

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    That would permit simultaneous flushing of gearbox and TC? (More inclined to separating the tasks - see below).

    Points taken, but before I give up on it entirely....
    Re overdrive - if it has to be done with the output shaft spinning - then surely that is OK if the cooler circuit is still connected at that point (and TC flushing done later as separate task)? (I'm unlikely to disconnect the prop shaft for this and rear wheels spinning in the air is a risk too far for me).

    As above, separating the tasks, I've come across another method to flush the gearbox internals independently of the TC. With the pan off, a pipe is inserted into where the filter is and its lower end is placed in a reservoir of fresh fluid and the engine started and the box run through the gears and what drains from the box is caught in a large drain tray. Has the advantage of only using as much fluid as required to flush the gearbox. This is tempting with output shaft stationary and accept overdrive circuit goes undrained. If the volume of fluid purged is worth the effort that is....

    This though is probably the decider. Of the 5.5 litres that in a normal fluid change goes unchanged - what proportion is in the TC and what in the gearbox internals?

    The reason I'm being so particular about this is I don't view the fluid change as merely replacing old with new. I intend using a much better quality fluid and want it to be the predominate fluid in the system.
     
  10. Schurkey

    Schurkey I'm Awesome

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    As I have already said--what's left in the trans accumulators/servos/fluid passages/valve body/piston housing is INCONSEQUENTIAL. I bet it's less than a quart. Probably half-a-quart. I've never tried to measure what comes out of a transmission that's being disassembled. It makes a big mess, a large puddle on the work bench...but half-a-quart makes a big puddle.

    The torque converter will hold multiple quarts. Exactly how many depends on the size of the converter. A bigass 14" converter holds more than a race-ready 10" converter.

    Total fluid capacity of the trans, trans cooler, and plumbing is likely to be in the neighborhood of 12 quarts. 11 1/2 quarts of new fluid IS the predominate stuff compared to the half-quart of residual. But let's be really generous--let's say there's ten quarts of new, and two quarts of residual. The new is STILL the "predominate" fluid.

    You are over-thinking this.
     
    Last edited: Sep 18, 2020 at 11:39 AM
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