Long time listener, first time caller…

I’ve been looking around for quite a while trying to diagnose my issues with my transmission. I have a 2001 Excursion with the 7.3/4R100. Has about 380k on the dash, runs great. Have a newish KC turbos stage 2 in it, single shot 180/30 (I think) injectors from Full Force a hydra tuner and a few other things I can’t remember at the moment. Over the past year or so I’ve had transmission issues. Some shifting issues and some gear engagement issues. I replaced about a 6-7 months ago the solenoid pack as the truck wouldn’t shift up without a lot of my effort to take the load off the transmission at specific times. Solved that issue and drove great again. It has also a brand new Shift Rite Valve Body kit (all 3 with upgraded components). Then lately it’s been on the decline again. The issue is that it drops into what feels like neutral, when hot, at a stop or slow down. I ran a line pressure test and I’m getting near-normal pressures when cold in each gear at idle, a little on the low side, but then when hot (about 160-170 on my trans temp gauge that reads from the pressure test port), I get about 20 psi at park in idle, then in all gears drops to about 5-8 psi. With my mileage and all that my assumption is the pump is bad and I’m going to replace it. Just wanted to get opinions from all the experts here and see if there’s something I’m overlooking before dropping a few hundred on a pump. When money is less tight I’ll do a full rebuild but I need it to get me by for a while I use the truck for work. Also - fluid is not burnt and no debris in the fluid minus what looks like maybe some clutch “dust” from some slipping. Any advice is greatly appreciated!

 

Assuming that you got 380k on this transmission too, the transmission is worn out. 20psi is not good at all. I suspect the lowest would be around 60-70psi.

Hydraulics are fairly simple to figure out once you know the basic rules. Since fluids can't be compressed, the pump does not cause the pressure. It just forces the fluid into an area where the fluid can't go anywhere. This is how the pressure is made. If there is no pressure release, something breaks. Since the pump is the first item that gets lubed, the pump is probably ok. But with 380k, it's probably just worn out, including the pump housing.

If you have any skills working on cars, transmissions are not that difficult. They look difficult but there are so many videos out there that break all the small steps down to make the job not so difficult.

Don't forget to flush/clean out the cooler lines. I would not remove the cooler bypass. I would rebuild/replace it.

 

I completely agree with this post.

 

I appreciate all the info! So what you’re saying is that it’s not necessarily the pump itself but potentially something downstream that’s not allowing pressure to be built within the system? That does make sense but where would I start to solve the mystery? Is there any way that I’d be able to narrow it down to what it could be or is it just it needs a “full rebuild” at this point? I’m not opposed to rebuilding it myself, just everything else had read had pointed me in the direction of the pump. I’m fairly good with cars/engines I’m a diesel mechanic, but I only work on industrial/aerospace generators, hydraulic pumps and Air conditioners, which is my reasoning for reaching out for help with transmission issues, I’ve really never worked on them at all other than manual transmissions and hydrostatic drives. Automatic transmissions baffle me for the most part, but I’m here to learn! That all being said if everything you’re seeing is pointing towards a rebuild rather than just a pump for now, could you point me towards a kit or set of parts that would be good and cost effective for my purposes? If there’s any other data that might help anyone assist in determining the root cause please let me know and I should be able to gather it. I have a halfway decent scan tool and a trans pressure gauge and everything else like that. Thank you all for the help!

 

Until you start checking things, no one can tell you what is wrong.

You could air check the clutch packs, that might tell you something.

I just look at things differently. You mention that you got 380k on the truck. I would not waste even a minute and just dive in thinking everything is worn out.

The pump sends oil to the lubrication circuit. Any/all those bushings could be worn causing the pressure loss. The rubber seals can be hardened, again, causing pressure losses, which can lead to low pressures. The pump, another wear item, can be the cause too. It's possible that the transmission filter is so plugged that the pump can't get the fluid it wants. Maybe the filter is not installed properly.

If you understand hydraulics, then an automatic transmission should be simple for you. You can ask all you want, but until you dive into this, you won't get a good answer.

Years ago, I had a front pump fail on me on my E4OD. I absolutely distrust anyone in the automotive industry, but I really had no choice but to get my transmission rebuilt by a local shop. That decision just cemented my idea that there are nothing but hacks pretending to be mechanics in my area. When the front pump failed, it made a howling noise before it finally failed. Since I did not rebuild that transmission, I can't say what exactly failed, but if you pump is noisy, I would start by removing the pump. But once the pump is out, you're only 30 minutes away from having the complete transmission disassembled. Withing a couple hours, you can have it apart so you can touch every signal part with your hands. I would not remove any transmission with that amount of miles on it without going through it. Rubber seals don't stay soft forever.

 

I’m all for diving into it, just having not pulled apart an automatic transmission before, I’m at a loss of where to start and just don’t want to end up with a torn apart transmission come Monday morning if I do this over a weekend and then still need to make it to work. I can remove the trans, I can pull the torque converter and the front pump but beyond that I don’t have a great grasp of things I should be looking at to determine cause of failure.

Really I’m just asking if there’s anything I should be looking at, things I can test that sort of thing that could potentially cause this issue. The pump is making a little whining noise as most hydraulic pumps will do when they’re going bad, so I do suspect the pump, if not already bad, is on its way out.

I’m going to be looking at plenty of YouTube videos and calling up some buddies that might have done this before. I know nobody is going to be able to diagnose my issue for me through a forum but I know there are people with lots of experience with transmissions that I don’t have on them.

If I were to pick up a master rebuild kit as well as a pump, would the parts in that likely solve my issue or is there something a lot of kits that don’t come with that might be the issue? When taking a trans to a shop to get rebuilt, is that all they’re doing, replacing parts with a kit that I could buy myself? Just looking for a little guidance is all.

 

Nobody can tell you where to go from here. You want to know what is behind door #3 without opening the door. I understand where you are at, but only you can take the next step. I can assure you, nobody knows what is wrong, just opinions on what might be wrong.

I am currently working on a long term project to get my F250/5.8/E4OD to have more power. I don't want my truck laid up for months/years. I elected to build my transmission first, then the engine. If I built the engine first, I might ruin the transmission. Since I did not want to have my truck on the rack for months, I purchased an E4OD core transmission. I think I spent $200, but I honestly do not recall. I got a transmission from a 95 but it was coincidental that it matched my year. I believe 95 and newer take less upgrades to make them like the later versions.

I spent months getting all the parts I wanted and when I had everything, I took apart the core and rebuilt it. I tend not to use the term rebuild because rarely does someone at home rebuild them as well as a large rebuilder. I replaced every wear part I could. All bushings, seals, bearings, clutches, plates, etc. I had plenty of time checking, double checking, questioning, rechecking, and testing everything I took apart. I swapped gearset with steel versions and used some that were installed in the 4R100. When I was satisfied that my Frankenstein transmission would work, I took a weekend and swapped it out. Although I did remove my transmission many times to 'tune' and 'tweak' the quality of shifts, it did work. If it did not, I still had my stock transmission I could put back in and figure out what I did wrong.

Maybe you can go down that path. Get a core transmission, go through it. Take your time. Basically, a complete D&A is just a bunch of small jobs. Once you complete those small jobs, it's a fairly small job to put all those parts together again. If something does not work/fit right, you still have plenty of time to figure it out and if you get upset, you can walk away to grab a beer or just come back when you have calmed down.

I guess where I am coming from is no one can help you much here but yourself. It sounds like you have the knowledge to tackle this project but are just a bit nervous to screw something up. Well, if you don't screw this up, there are plenty of chances in life to screw up something. It's just part of life.

 

What's caused this issue is 380k miles. It's just worn out. All of the seals are hard and worn. Clutch plates are worn, if they still have any friction material left on them. Clearances in the pump are above spec, allowing pressure leakage. There is no one thing that you can change that will fix this, except possibly replacing this transmission with one from a lower mileage truck.

 

How To Reman The E4OD/4R100 - Complete Video Walkthrough

 

That video series is very informative, be prepared to fall asleep. As far as I am concerned, if you follow all those videos to a tee, it would be difficult to believe the transmission would not work.

I believe I spent several months watching all kinds of videos that show the tear down of these transmissions. Many show the actual failure of the transmission. The more videos you watch, the knowledgeable you get and at some point, you start to think, 'I can do that'.