I'm looking at a '95 4x4 Ranger that drives off the lot fine, and after a couple minutes of driving the trans starts slipping. Dealer had transmission shop change the fluid (Car Fax shows that had been done also by previous owner before trade) but problem still there. I'm thinking foaming, torque converter, servo ??? Anybody heard of it happening before? I think it a 4R55E trans.

 

Welcome to the forum

1995 will have a 4R automatic, 44E if 4cyl or 3.0l V6, 55E if 4.0l V6, but they are both the same as far as troubleshooting
The A4LD, 1985 to 1994 Rangers
And the 5R's 1997 and up Rangers
Are also the same transmission

You can Google: 4R55E slipping

But you will find pretty much the same answers if you type in any automatic transmission model, Ford, GM, Toyota, BMW, ect..................

All automatics operate the same way, and have operated this way since they were first used, they all use ATF fluid pressure
The ATF Pump inside the transmission is turned by the engine, via Torque Converter's outer case
That pressure is routed thru the Valve Body
In 1995 and up Rangers the valves in the valve body are operated by electric solenoids
These solenoids route pressure to the Clutch Packs and Bands(brakes), and these are what select the output ratio
There is only 1 set of gears in an automatic, but it has variable ratios which are selected depending on which clutch is engaged and which Brakes(bands) are applied

Slipping can be quite a few things, a clutch slipping, worn out, a band not holding, worn out
Or low pressure at the clutch or band so it can't engage fully or hold firmly

Low pressure can usually be addressed by changing the Valve Body, which can be done without removing transmission
Transmission pressure can also be tested using test ports on the sides of the transmissions, gauges need to be rated up to 300psi
You can rent a pressure tester, and the correct pressure you should see in each gear is available on line.

If clutches or Bands are worn out, 250k miles or so, then you need a full rebuild to replace them, along with pump and a few other hard parts

If an automatic has been slipping for awhile then if the clutch packs or Bands were not worn out, they probably are now, slipping in an automatic is the same as "riding the clutch" in a manual, or "riding the brakes" in any car, it wears out the friction materials faster

Good info here on these transmissions: https://atracom.blob.core.windows.ne.../2003_5_50.pdf

 

Thanx for the reply. I pretty much knew most of it, I rebuilt a C4 many years back, like when I was 40 years and tears younger (just turned 80). I haven't opened the hood or test drove the truck yet. So I don't know if the trannny has a separate cooler or it flows thru the radiator. The selling dealer said it has been driven by 4 different possible buyers who all experienced the same result. That's telling me it's temperature or time related. Question... is there an external high pressure servo/valve or adjustment?

 

There are external band adjusters, but no pressure adjustment

The EPC Solenoid is used to adjust pressure and you can adjust it but have to remove the pan and solenoid
Info here: http://www.atraonline.com/gears/2002...2002_11_22.pdf

1995 was the first year of the 4R55E, which was an A4LD with a new valve body with all solenoid control
First year of anything is where car makers "go to school" on real world issues that come up, so if valve body hasn't been changed then a newer version valve body might just be the ticket, it will have the updates Ford learned about over the years.
There are also shift kit upgrades that many have used and like.

But as said if the problem is in clutch packs or bands then.............it would still be slipping

If there have been 4 previous "lookers" then offer them a lowball price, asking price minus cost of valve body and your time
Or call trans shop and get a quote on pressure test and then cost of installing new valve body and deduct that from the asking price

 

Thanx Ron. I went by today in warm and dry weather and gave the truck a long hard look. It has had a hard 25 years. The power seat still worked, but the oil pressure at start up went from low to lower; drivers window went down but struggled to get up; radio wont shut off; belts dont retract and on and on. I'm giving up on it and will go back to work on my '94. It's only got 83,000 on it.... but like the '95, it needs a tranny job. Just nobody left locally to do it. Thanx again.