I have a 1999 f350 7.3 4x4 with about 115k miles. I had some transmission overheating issues about a couple weeks ago. I changed the fluid and filter and things seemed better. Now I am getting 60psi line pressure at start up but after 5 minutes I gradually lose my pressure to zero. If I restart the truck I get the 60psi and then lose the pressure again in five more minutes. I was thinking it was the EPC solenoid, but before I start throwing parts at the problem does anyone else have a theory?

 

If the EPC drops to zero PSI the line pressure will remain at about 60 PSI. The EPC cannot cause it to go lower than that. The solenoid isn't the cause of the problem.

Is the fluid level correct when checked warmed up, engine idling, and the trans in park? Are you measuring the pressure at the test port?

 

the fluid level is good and I’m measuring at the test post. The problem reoccurs at both cool and warm temp. My next guess is a clogged filter, I changed it before, but perhaps the new one is defective or restricting flow. This would explain the early good flow numbers and gradual decrease in line pressure as dirty atf and restricts the flow.

 

It was the transmission filter. I took the filter I installed 2 weeks ago and it looked like the tin man used it for TP. I replaced with new filter and pressures are holding. I’m not sure how much clutch material I have left but that’s another days problem.

 

IF that is a 2 week old filter, I would not be driving it. You've got issues. If you insist on driving it, get a AAA membership. You will need it.

 

Well towing anything is out of the question. I took a trip to the dump and we were good to go. I do understand I’m working on borrowed time.

 

That's not clutch material, that looks like converter.

 

Converter seems to be fine. I drove it for about 50 miles over the last couple days both in town and highway and things appear fine. Does anyone have a link to be able to do proper diagnostics on a 4r100 or is it just wait for it to fail at the worst posable time?

 

The stuff on the magnet is ferrous material, aka steel. Where did the steel come from? There are lots of opinions, but that is all they are, opinions. Until the transmission is disassembled and inspected, nobody knows. If all the items inside the transmission look good, then it's probably from the converter. Why? Because the average Joe is not going to cut one open to prove a point.

The steel could be roller bearings/races. Could be clutch plates where the clutches are worn out to the steel backing. Could be gears too. Normally, if it is a bearing, you might just hear something. I've never heard worn clutches make noise. They just tend to slip because the piston cannot move that distance to give it a firm hold. But then again, I am just going off my experiences in the past.

So, my take is you got clutch material and steel. I believe the steel is from the clutch plates. Including the ones inside the converter. The OP stated that the fluid/filter was replace recently [weeks?] If that is true, I would have a tow truck on standby or start removing all the VINs so you can just grab the plates and walk away.

If you do elect to fix it, you need to know for certain all the debris is out of the cooler/s. There is no sure fire way of knowing so replacing is the best way. If not, you might just be asking the same question once the rebuilt one is back in.

The diagnosis is, you got debris in the pan that should not be there. The transmission must be disassembled to find the root cause. Most people bail when they hear that. Unless aliens put that stuff in there, something is falling apart. Old cars/trucks wear out. It's part of what they do. Things last longer with the right services/maintenance. Engines tend to get more love than transmissions, until they start to fail. Then people wonder why.

But then again, it's just another opinion that cannot be proven.

 

Put me in the new filter/fluid then drive it camp. My truck overheated badly while towing and later I found bass boat glitter in the fluid. New filter and fluid and it's been fine for 30k since.

Plus I added a 6.0 cooler and valve body.

Unless you plan on an endurance speed run across the US I'd run it and keep an eye on the color and smell of the fluid.

Fix it when it's broke.

 

Brass is different than steel. Just saying.

In some ways, it really does not matter. If you are going to buy a transmission and swap it out, the core will never be used in your truck. If you plan on repairing it yourself, you might just be ruining good parts if you keep driving it.

 

Funny I used the bass boat glitter line myself when describing my transmission pan after it over heated it and the smell of the atf as being that of a gentleman’s club with serious hygiene issues. I of course changed that all out. I have a good transmission shop which will get a visit if a get a slip. Also I looked up clutch lining content and steel is frequently a component.

 

With a 7.3 diesel, odds are above average that you won't be able to hear a bad bearing in the transmission with the engine running. Won't be able to hear it without the engine running either, but for a different reason.