Transmission won't go into first, second or drive.

Hi,

Does the transmission shift into any forward gears? For example, if you place it in low 1, does it go into gear? Also, did this happen all at once?

Since you had the valve body out, then some of the fluid is new. However, was it very dirty prior to the service? Have you flushed the cooler lines?

I have a feeling it could be related to low line pressure. Let me know about the cooler lines.

Take care,

Joe

I have seen that happen on vehicles with a plugged filter. When the engine is turned off, the debris drops into the pan, and the transmission works for a short time until it sucks the dirt back into the filter, but you already replaced the filter. I feel it is something to do with line pressure. The only part I'm not sure of at this point is this. Reverse takes the most pressure to operate and functions from the same clutch pack as first gear. It's referred to as the low/reverse clutch.

If I had your vehicle, I feel the first thing I would check is the line pressure. If it's low, we need to determine where the problem is.

Do me a favor. Please confirm if this has a 4.6V8 or a 5.4V8. Also, let me know the condition of the fluid and filter when you changed it.

If you look below, the attachments are the directions and pressures for testing line pressure. They are for the 4.6L V8. If that isn't the correct engine, let me know. The pressures appear to be different.

Let me know your thoughts and if you feel comfortable performing the test below. Hang in there. We'll figure this out together.

Take care,

Joe

See pics below.

Hi,

It certainly could be the clutches, but normally, you will notice them slipping before they completely fail.

If I had the truck for diagnostics, found good line pressure, the next thing I would do is flush the cooler. If the transmission fluid was extremely dirty, it could have been clutch material. So, your father is certainly thinking in the right direction. However, before I would pull the unit, I would flush the cooler.

Does this truck have an auxiliary cooler or is it just one through the radiator? I attached a pic below of the auxiliary cooler's location.

Let me know.

Joe

Hi,

It is very possible that the cooler is integral with the radiator, and you don't have the auxiliary cooler.

Let me know.

Joe