My goal in this writeup is to describe a safe method of changing 42rle fluid w/o a risk of running it dry and to define a process that is safe and completely repeatable. Running the transmission dry is the #1 risk of trying to change the transmission fluid at home.
In this how to guide (https://wranglertjforum.com/threads...c-transmission-on-your-jeep-wrangler-tj.5848/), the risk of running it dry is not addressed, so this is why I am posting another guide.
The most important point about fluid exchange is how to add the fluid while the oil pump in the 42RLE is pumping the oil out. The problem starts with the oil pump working really fast - in my 42RLE the oil pump pushed 1.5 in minute or less, and the process of topping the fluid through the deepstick being very slow.
My solution to this problem is to use a combination of deepstick fluid exchange plus infusion can that will compensate for the oil pump pumping the fluid out fast.
How my infusion can looks :
I took these:
- a gas can ( https://www.amazon.com/dp/B087RSN3Q4/?tag=wranglerorg-20). I bought these for 20 bucks once for hurricane Harvey, so I had spares in my garage.
- 2 pieces of 5/8 inch garden hose from the junk that i had in my garage (i think it originally was https://www.homedepot.com/p/Teknor-...ERCH=REC-_-pipsem-_-100134485-_-100661317-_-N). Had it as junk in my garage.
- 3/4 inch bard ball valve (https://www.homedepot.com/p/Apollo-...-Ball-Valve-with-Tee-Handle-EPXV34T/305469340). 12 bucks, bought from home depot.
- 1/2 in. x 2 ft. White PEX Pipe - https://www.homedepot.com/p/Apollo-1-2-in-x-2-ft-White-PEX-Pipe-APPW212/301541216. (2 bucks).
- ATF+4 from Mopar, like https://www.amazon.com/dp/B07VFJYQJ3/?tag=wranglerorg-20 and https://www.amazon.com/gp/product/B00BV4D182/?tag=wranglerorg-20
The can itself - I have a cut a hole in it's bottom, so can fill it and the air can enter when the fluid is draining. Then I removed the flow limiter (the one that needs pressure to let gas to flow out). Basically fluid can flow through the yellow pipe freely. I have added a screw in it's bottom so that i can hang it easily from the top of the trunk.
The valve enables me to control when i want the fluid to flow out of the can.
The white PEX pipe allows sticking this thing into deepstick, and sitting it inside and not moving around.
I used this pump - https://www.amazon.com/gp/product/B00XAKQ0YC/?tag=wranglerorg-20,
I used this bucket:
I used this drain hose (the heavy nut at the transparent hose is just to add weight to keep it inside the bucket)
The process itself:
- Deepstick stage: I sucked out of transmission 3 quarts of ATF+4 and poured in new fluid. You can suck out precisely 3 quarts through the deepstick. The point in doing it is to reduce the amount of fluid that will need to flushed by almost completely replacing what you have in the pan area. I think it has 4 and something quarts there. Take a look at the fluid and see how dirty it is. Take a small sample (i used a small water bottle), so that you can compare with the fluid that will come out of the transmission at the end of the process.
- Pour 1 large can (1.3 gallon == 5.2 quarts) of Mopar ATF+4 and 2 small cans of quart each into the bucket. Then measure this level by putting a small piece of tape on the side of the bucket. It is ugly but simple. The idea is that during flush, the fluid coming out of the transmission will pour into the bucket and you will shut down the engine when the fluid in the bucket reaches this tape.
- Hang the infusion can from the top of the trunk and make sure that the valve is closed.
- Pump (using the manual pump) the fluid from the bucket into the infusion can.
- connect the drain hose to the pipe on the radiator on the drivers side (take into account that if you have older 3 speed, you need to connect the hose on the passenger side).
- Put the empty bucket with tape marking near the driver seat (near the driver door), so you can see it while having your hand on the ignition key.
- Put the drain hose into the bucket (a heavy nut helps keep it inside the bucket)
- Open the valve on the infusion can so the fluid starts to flow into the deepstick
- Start the ignition (do it like maximum 20 seconds after opening the valve, as you do not want to risk overfilling), and watch all the junk fluid starting to flow out of the transmission into the bucket.
- Shut down the engine when the fluid in the bucket reaches the tape.
- Infusion will still be pouring fluid into the deepstick when you shut down the engine as it pours fluid slower than the transmission pump to the bucket, but not much slower. It will finish quickly, wait to see that the can is completely empty. When it's empty, you can close the valve.
- Remove the infusion can and put back the deepstick.
- When you remove the drain hose from the radiator, gather the small quantity of fluid that will leak when you disconnect the hose (I used a small water bottle). Keep it for comparison.
- connect the transmission return hose to the radiator
- clean the mess and you are done.
And the end the fluid inside the drain hose will look like this. You will see how the color of the fluid changes throughout the flush, reaching pure clean ATF+4 at the end.
Remember I said that I took a small sample from the 3 quarts that I sucked out using the pump through the deepstick?
So this is the comparison. You can see that first sample of fluid coming out of 42RLE on the left is dark and the new fluid on the right looks very different. The sample on the right (from the hose disconnect stage), looks pretty much identical to the clean, new ATF+4 , so seems like it worked.
To summarize:
- This enables you to change the fluid in 42RLE w/o any risk of running dry, if you limit yourself to the quantities that i have listed. if you try to flush beyond the 7.2 quart, i am not sure that you will avoid the risk of running dry.
- Total fluid replaced was 10.2 quarts (3 in deepstick stage and 7.2 in the flush stage).
- you can repeat this process easily, and flush additional 7.2 following the same steps if you have extra money and want to make sure that all old ATF+4 is out. Although i believe that that steps that I have performed (with total of 10.2 quarts replaced) are more than enough, as you can see empirically.
- I did not have a chance to drive it a lot after fluid change, so will follow up whether it drives anyhow differently.
In this how to guide (https://wranglertjforum.com/threads...c-transmission-on-your-jeep-wrangler-tj.5848/), the risk of running it dry is not addressed, so this is why I am posting another guide.
The most important point about fluid exchange is how to add the fluid while the oil pump in the 42RLE is pumping the oil out. The problem starts with the oil pump working really fast - in my 42RLE the oil pump pushed 1.5 in minute or less, and the process of topping the fluid through the deepstick being very slow.
My solution to this problem is to use a combination of deepstick fluid exchange plus infusion can that will compensate for the oil pump pumping the fluid out fast.
How my infusion can looks :
I took these:
- a gas can ( https://www.amazon.com/dp/B087RSN3Q4/?tag=wranglerorg-20). I bought these for 20 bucks once for hurricane Harvey, so I had spares in my garage.
- 2 pieces of 5/8 inch garden hose from the junk that i had in my garage (i think it originally was https://www.homedepot.com/p/Teknor-...ERCH=REC-_-pipsem-_-100134485-_-100661317-_-N). Had it as junk in my garage.
- 3/4 inch bard ball valve (https://www.homedepot.com/p/Apollo-...-Ball-Valve-with-Tee-Handle-EPXV34T/305469340). 12 bucks, bought from home depot.
- 1/2 in. x 2 ft. White PEX Pipe - https://www.homedepot.com/p/Apollo-1-2-in-x-2-ft-White-PEX-Pipe-APPW212/301541216. (2 bucks).
- ATF+4 from Mopar, like https://www.amazon.com/dp/B07VFJYQJ3/?tag=wranglerorg-20 and https://www.amazon.com/gp/product/B00BV4D182/?tag=wranglerorg-20
The can itself - I have a cut a hole in it's bottom, so can fill it and the air can enter when the fluid is draining. Then I removed the flow limiter (the one that needs pressure to let gas to flow out). Basically fluid can flow through the yellow pipe freely. I have added a screw in it's bottom so that i can hang it easily from the top of the trunk.
The valve enables me to control when i want the fluid to flow out of the can.
The white PEX pipe allows sticking this thing into deepstick, and sitting it inside and not moving around.
I used this pump - https://www.amazon.com/gp/product/B00XAKQ0YC/?tag=wranglerorg-20,
I used this bucket:
I used this drain hose (the heavy nut at the transparent hose is just to add weight to keep it inside the bucket)
The process itself:
- Deepstick stage: I sucked out of transmission 3 quarts of ATF+4 and poured in new fluid. You can suck out precisely 3 quarts through the deepstick. The point in doing it is to reduce the amount of fluid that will need to flushed by almost completely replacing what you have in the pan area. I think it has 4 and something quarts there. Take a look at the fluid and see how dirty it is. Take a small sample (i used a small water bottle), so that you can compare with the fluid that will come out of the transmission at the end of the process.
- Pour 1 large can (1.3 gallon == 5.2 quarts) of Mopar ATF+4 and 2 small cans of quart each into the bucket. Then measure this level by putting a small piece of tape on the side of the bucket. It is ugly but simple. The idea is that during flush, the fluid coming out of the transmission will pour into the bucket and you will shut down the engine when the fluid in the bucket reaches this tape.
- Hang the infusion can from the top of the trunk and make sure that the valve is closed.
- Pump (using the manual pump) the fluid from the bucket into the infusion can.
- connect the drain hose to the pipe on the radiator on the drivers side (take into account that if you have older 3 speed, you need to connect the hose on the passenger side).
- Put the empty bucket with tape marking near the driver seat (near the driver door), so you can see it while having your hand on the ignition key.
- Put the drain hose into the bucket (a heavy nut helps keep it inside the bucket)
- Open the valve on the infusion can so the fluid starts to flow into the deepstick
- Start the ignition (do it like maximum 20 seconds after opening the valve, as you do not want to risk overfilling), and watch all the junk fluid starting to flow out of the transmission into the bucket.
- Shut down the engine when the fluid in the bucket reaches the tape.
- Infusion will still be pouring fluid into the deepstick when you shut down the engine as it pours fluid slower than the transmission pump to the bucket, but not much slower. It will finish quickly, wait to see that the can is completely empty. When it's empty, you can close the valve.
- Remove the infusion can and put back the deepstick.
- When you remove the drain hose from the radiator, gather the small quantity of fluid that will leak when you disconnect the hose (I used a small water bottle). Keep it for comparison.
- connect the transmission return hose to the radiator
- clean the mess and you are done.
And the end the fluid inside the drain hose will look like this. You will see how the color of the fluid changes throughout the flush, reaching pure clean ATF+4 at the end.
Remember I said that I took a small sample from the 3 quarts that I sucked out using the pump through the deepstick?
So this is the comparison. You can see that first sample of fluid coming out of 42RLE on the left is dark and the new fluid on the right looks very different. The sample on the right (from the hose disconnect stage), looks pretty much identical to the clean, new ATF+4 , so seems like it worked.
To summarize:
- This enables you to change the fluid in 42RLE w/o any risk of running dry, if you limit yourself to the quantities that i have listed. if you try to flush beyond the 7.2 quart, i am not sure that you will avoid the risk of running dry.
- Total fluid replaced was 10.2 quarts (3 in deepstick stage and 7.2 in the flush stage).
- you can repeat this process easily, and flush additional 7.2 following the same steps if you have extra money and want to make sure that all old ATF+4 is out. Although i believe that that steps that I have performed (with total of 10.2 quarts replaced) are more than enough, as you can see empirically.
- I did not have a chance to drive it a lot after fluid change, so will follow up whether it drives anyhow differently.
