On my 04.5 I've been having some coolant and trans temp issues. Coolant temps go up to about 200-210 and trans temps get to about 160-175. I've replaced the water pump,180 degree thermostat, a new fan clutch and the trans temp is reading from the pan. I know the trans temps aren't bad but it normally doesn't get above 150-155 on a 90+ degree day. Coolant on the other hand never got above 180 unless i was working the truck hard. After a 15-20 min drive is when things start to heat up, stays there for a few minutes and then creeps slowly back to normal. And this is with highway, city and or just idling in neutral. Doesn't matter. I don't have any coolant or trans fluid mixing and I'm not having any changes in levels from the trans or coolant. Could I have a blockage in my heat exchanger on the side of the block? Don't want to go through another transmission build or engine for that matter right now. Advice?

Sorry it took so long to get back with y'all on my issue but I figured it out. It wasn't the 180 degree thermostat (which I never had an issue with before) or the cooling system at all for that matter. It was the factory trans cooler thermostat that was sticking and so the fluid was only running through the bypass itself. That caused the trans fluid to heat up and in turn the coolant also since it goes through the heat exchanger on the side of the block. Since I live in south Tx where cold temps aren't an issue I bypassed the thermostat in the cooler and at the same time deleted the heat exhanger. I already had a Derale Hyper cool 24 row cooler so I new it wouldn't be an issue. My trans temps in the pan are 120-130 and before I had any issues it was at 150-160. So I dropped 30 degrees which is great. I know that the thermostat should be in the outlet side line also which would be about 30 or so degrees higher but I didn't want to change that yet. I'm going to install a remote filter and I'll do it at the same time.   And I also did away with all the hard lines and deleted the one way check ball. No restrictions at all now. Just hope this trans lasts long enough to complete my 4r100 trans swap. Thanks for all the advice                               

The thermostat is in the factory cooler in front of the radiator. Removal of the thermostat is a little tricky with the cooler still installed but it's possible with a little patience. Here's a quick DIY: 1) Remove the internal c-clip that is in the end of the bypass, once you do that I took a simple blow torch and gently heated the aluminum block around the plug and the spring pressure popped the plug out almost flush with the end of the cooler. Then take a punch and quickly push in on the thermostat and let is release quickly. This took a couple of times but it came out. Be careful not to lose anything as it is under pressure. I had a rag in front of it to catch everything just in case. After you remove the thermostat and spring, clean them all up with brake cleaner. Make sure the inside of the cooler is clean and that the bore didn't get scratched in the process. Remove the small rod that is in the brass part of the t-stat, take the brass piece and reinstall it backwards (smaller end facing outwards), install spring. Oil the end cap (with new o-ring) with trans fluid and install. While pushing on the end cap install the c-clip. 

TOMORROW after work i'ma take mine apart!! thank you for this. my trans run at same temp as engine. just slower getting there.

TOMORROW after work i'ma take mine apart!! thank you for this. my trans run at same temp as engine. just slower getting there.

No thanks needed. Make sure you have a replacement o-ring beforehand just in case. Hope it fixes your problem.

What does turning the brass around backwards do? and the little pin thing in the middle.. can you explain WHY doing the aforementioned steps fixes it...

one more question, where is this check ball.? i'd like to remove it as well. i always let my truck run in neutral for a round 2 min every morning to get things lubed before take off.

one more question, where is this check ball.? i'd like to remove it as well. i always let my truck run in neutral for a round 2 min every morning to get things lubed before take off.

The check ball is to prevent drain back of the cooler circuit oil back into the pan via the converter seals to not have to let it run for a while to get lube pumped back through the cooler circuit, you don't want to or need to remove this.

The check ball does prevent drain back from the converter but as long as you put it in neutral when you start it then your fine. And I've done this to other trucks and have had no problems. Many times they have sat for over a week and they operated like normal without having to let the fluid circulate in neutral. But every truck is different. And the check ball is known for getting clogged up and not letting fluid flow like it should. And you would be none the wiser. And by it's design it is a restriction in the line. As far as the t-stat in the oem cooler, turning the brass part around blocks the bypass part of the cooler and lets fluid flow through the main part of the cooler full time. Unless you live in a place where it barely gets above freezing then I wouldn't think twice.

one more question, where is this check ball.? i'd like to remove it as well. i always let my truck run in neutral for a round 2 min every morning to get things lubed before take off

Of the 2 trans cooler lines that go to the factory cooler on the drivers side, it's the outermost one if your looking at it with the wheel well removed. Just follow the front line out of the trans. It'll come out of the top side of the heat exchanger and go to the cooler.

one more question, where is this check ball.? i'd like to remove it as well. i always let my truck run in neutral for a round 2 min every morning to get things lubed before take off.

 And the check ball is known for getting clogged up and not letting fluid flow like it should. And you would be none the wiser. And by it's design it is a restriction in the line.

 

If that ball gets clogged you have a massive TC lockup clutch or other mechanical failure that has happened or is happening and you will know it in a quick spell. It is a low pressure open center flow system and I have dug the check ball out of several fittings over the years to look at and by design it is not a restriction as it likely has more area to flow fluid past in the fitting than the actual oem line itself once unseated with what is a very light spring.