DIY: Full Flush for Automatic Transmission

I don't think you should bypass the radiator. Just make sure to mount it in the correct orientation and replace the lines from the stock cooler to the Hayden.

Im loving mine so far. I took a 200 mile day trip and never went above 159F with an ambient of 95F at times and plenty of inclines.

 

It's up to you if you want to bypass the radiator cooler. I did bypass mine. I'm running a single cooler and so far it's been better than the stock inline oil cooler. I went with a tru cool cooler because it has low pressure bypass, where the Hayden doesnt. Low pressure bypass helps with cooler weather. Watch the video I posted earlier about my setup. Should help you answer some questions.

 

We know the temp has to be between 115-130 degrees to be in Temp Check mode where the A/T Temp light stays on. It starts to flash if you go over 130 degrees. We know that the A/T fluid expands greatly at hotter temps which is why you don't want to drain any from the overfill plug when the temp is too hot (above 130).

Technically couldn't you remove the overfill plug immediately after starting the temp check process? I'm not talking about waiting until the A/T Temp light comes on solid either but just when it initially starts to blink as it's warming up from a completely cold start. At that phase you wouldn't expect any fluid to drain out since it's cold and hasn't started to expand yet. Could you remove the overfill plug and just wait until it the A/T Temp light comes on solid and then watch it until it just barely weeps and then re-install the plug?

Does that sound correct?

 

I’m sure this method would work. You’re essentially doing the same thing, just in a different order. Personally, I found it very easy to monitor trans temp until it reached 115 before pulling the plug and draining the excess.

 

Why would you even think about altering the procedure? The procedure is simple enough after you practice jumping the wire to the pins and getting it in check mode. I would assume the factory method assures all the fluid is at the correct temp. where your method my not, since it is able too escape during the warm up period.

 

I wouldn't expect any to escape during the warm-up (unless you were greatly overfilled to begin with) since the fluid has expanded yet. Once it expands given the right temp range then it should start to peek over the overfill plug and come out. Isn't this a correct assessment?

 

You could be right. But what if it doesn’t heat up evenly?

 

Good point.

 

I found that mine took a while to get it to reach temp and was rising slowly. You should have plenty of time to get the check drain plug out. You can leave the fill plug loose, and if it needs more fluid just squirt some in until it starts weeping, then button it up.

 

OK, I'm having a problem getting this into A/T Temp check mode (I think). I follow the steps and get the initial 2 seconds illumination of the A/T Temp light after putting it back into N for the final shift and then when I put it into P the A/T Temp light just comes on solid. This was after a 5 hour cold start. I was getting a IR Gun Pan reading of 95 degrees before even starting it so I don't think the fluid was at Temp yet. I did read post #369 where John says that the A/T Temp light not turning off after shifting back into Park but rather staying lit is a sign of "Overfill". After leaving it it Park for another 5 mins or so the light blinks indicating it's now too hot (over 100 degrees). I have tried the same thing the other day after an overnight cold start and still ended if with the A/T Temp light just staying on solid after put into P (no way it was at temp). While it is possible I maybe put in nearly 1 quart more than I took out I can't be sure since I spilt some and lost track. How would the tranny know it was overfilled on a cold start anyway? Any suggestions?

 

So what was the ambient temp. when you used the IR gun?

 

about 85 degrees

 

Since the ambient temp. was close to what the IR gun read, you didn’t have to far to go to get to 115 degrees, which is the check mode temp. I think as soon as you saw a solid tranny light, you were good to pull the check screw and let the excess trickle out. When the fluid is warm to start with, It doesn’t take very long. You can always let it sit over night and recheck in the morning when it’s cooler.

 

This. I had the same thing happen to me. It took me about 1 minute or so to reach temp after trying to get into temp mode for about 2 minutes with a 90F ambient temperature. I rechecked later on after it cooled down outside and it was correct.

 

@james99, So, what happen? Maybe others can learn from your problems.

 

Problem was due to low oil level. I end up adding 1-1/2 quarter.

 

Personally I don’t think it’s super important. I guess you could fill it sitting on level ground and then drive it up on ramps to level the pan and see how much the fluid level is off. I doubt there would be much difference. It doesn’t have to be exact, just fairly close.

 

Excellent write up. Best I've seen for tranny fluid change

 

I’ve been using fusion app to monitor my tranny temps. I’ve noticed the tranny is normally 10 degrees warmer than ambient temp. Also, I’ve noticed that the temp check range on my truck (2010) is 97-115. So if the weather is too warm it’s not practical to check my fluid level.

 

@chris4x4 would it be possible to make this thread sticky? I’ve had to reference it a few times and it has proven difficult for me to quickly locate using search since there’s so many other threads that use relevant search terms. Thanks for considering!