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Auto trans fluid flush DIY

9K views 10 replies 4 participants last post by  cclngthr 
#1 ·
This morning I had a customers Elantra in the shop for a 60K service. Rather than going to a dealer for the trans flush, I asked Equus about the way he did his. I followed his instructions and designed an easy method to do the task. However, since this involves changing 4 gallons of fluid, and involves having the car in gear and wheels spinning, I want people to take care in doing this. I suggest have a helper to start the car and put it in gear and help hand you open bottles of fluid. It is best if you pour new fluid in at the same rate as it is being pumped out of the trans. I had a rollable table where I had organized open bottles of fluid and my materials. For me, this was easier.

Materials:
Jack and jackstands
18 quarts of SP-III automatic trans fluid for the XD. I suggest 20 for the HD and NF
2 cans of Hyundai trans cooler flush (comes in a spray can that the cooler line gets put into the spray nozzle)
5/16 inch hose that is about 8 feet long. I used a clear hose
5/16 inch by 4 inch long steel tubing
2 hose clamps
5 gallon bucket with a lid that has a small cap
drain pan
Tall funnel that fits in the trans dipstick tube


1. Jack front of the car up so BOTH wheels are able to spin freely. Place jackstands on the frame and secure car on stands. Make sure the e-brake is set and car will not move.
2. On the top of the transmission are 2 cooler hoses. On the XD, the passenger side one pushes fluid TO the cooler and the drivers side one is the return line. Since I have added a extra cooler and filter, the filter, if you added one gets removed.
3. Remove the RETURN line (drivers side line) and attach your hose and tubing to that with clamps. The other end gets put in the empty bucket. Start car and put it in drive to see if fluid runs to the bucket. It should. Shut car off.
4. Get 15 quarts ready, open and ready to pour. Put funnel in the dipstick tube and make sure it can remain there.
5. I chose to have the fluid run through the cooler as well. This was easier for me to do. You will use the cooler flush later. Start car and put it in 3rd gear DO NOT REV ENGINE. Fluid should be running to the bucket. At this time you NEED to pour 15 quarts of fluid in the transmission about the same rate as it is running out of the transmission. It is not gushing out, but is flowing out at a medium rate. About 12-13 quarts later, you should begin to see the fluid run out cleaner. The XD trans holds 12 quarts and the HD and NF hold 15 quarts. To adequately flush the trans you need to run MORE fluid through the trans to get all the dirt out. At the 15th quart, shut engine off and put it in park.
6. With NEW fluid in the trans, you now can unhook the PASSENGER side cooler line at the trans and put 1 can of the flush through the cooler. I chose to do this last because for me, it was easier. Instead of the bucket, I used the drain pan for the flush solution.
7. Put the long hose and steel tubing on the cooler line you put the flush solution through. On the other line, put the 2nd flush solution can in and use the entire contents of the can.
8. With new fluid in the trans and clean cooler, I now put the cooler hose back on the push line (passenger side line) of the trans. On the other hose, I put the long hose back on and started the car until the fluid started to run out of the hose. Shut car off and reattach hose to the transmission. Since I also added the filter, this gets installed as well.
9. Lower car, start car and check for leaks. In neutral, check the level of the fluid. It should be on the cold line on the stick. If it is higher, you can unhook the return line and drain enough fluid to get it to that point; if it is low, add enough fluid so it is at the cold line. Drive car until the trans is hot (about 10-15 miles). Recheck fluid and top off if needed so the level is at the top hot line. Drive car 5 more miles and recheck fluid. It should be at the top HOT line.

Your automatic trans fluid is now brand new and clean for 30K miles.
 
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#5 ·
If you don't feel comfortable doing it yourself, it may be best to go to a dealer. The process is messy though and getting oil splattered on the floor is a great possibility.

I don't have a flush machine, but do this on my customers cars because I want to have control over what is done and don't want mistakes. I also need permission from the customer to post pics of their car, which is the reason why I have not posted pics as of yet. When I do it on my car, I will do that.
 
#7 ·
Just bringing this thread back up. Im looking into doing this, but there are a few things I am confused. A hose has two ends so when it is removed, connecting the cooler to the tranny, what end does the drain tube go into? Depending on what is being done I guess. I am guessing if I am flushing the tranny, the 8' tube needs to be added to the side that is on the cooler pushing the fluid to the tranny, the driver side, so the flow of fluid is, dipstick>tranny>cooler>bucket, right? As for the filter, does it go on the driver or passenger side? As long as the direction of the flow in the filter is the same as that of the fluid, does it matter? Also I am confused about flushing the cooler! for step 7, after you flushed the cooler from passanger side out to the bucket waiting on the other end, you need to attach a steel tube and the hose on that end to now do the flush the opposite direction?
 
#8 ·
If I understand your question right, you have a closed loop system where fluid is flowing from the trans through the passenger side cooler line through the cooler and back in the trans through the drivers side, you are asking which line to disconnect?

I usually disconnect the line from the drivers side tube on the trans (return line). You put the hose coming from the radiator cooler into a bucket (I find it is easier to use a hard line to attach two hoses together) and have a longer hose going to the bucket.

I then install a short hose with a funnel to add fluid as it is running out.

After everything is flushed I reconnect the hose I originally removed back to the trans.
 
#11 ·
That drains it too fast. You can't poor fluid in fast enough. The cooler line has a slower flow plus it flushes the torque converter and screen better. When you empty the trans before the torque converter, you could do some damage because the pump would get air into it and the moving parts (input shaft) are still moving even in park).
 
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