Please note - this applies to the 4 speed autos from EA series II onwards....
Since we have had a lot of talk about faulty 4 speed auto's lately, I thought I would share the fruits of some research and labour.
I have an EL 6cyl wagon with the BTR95LE 4 speed auto. I drive it fairly hard, it's used to tow a ski boat a lot, and the tranny is showing a bit of wear as well as a propensity to burn transmission fluid. It has the extra factory cooler that comes with the tow pack, but it is too small for the job. This is made worse by the fact that we often tow through a hilly region on 35 degree plus days. Lately it has been fairly sad with a fair bit of flaring between shifts and a bit of a slip and then thud on kick-downs.
Now, I have had the transmission serviced several times before, where they drop the sump and change the filter and replace the 3.5litres it holds, for $140. Unfortunately this does not account for the other 7 odd litres of contaminated fluid. I understand that there are some specialists that can do a complete fluid flush but there are none in this area, and after speaking to a couple of workshops in Melbourne we figured out it wasn't too hard to do at home. So here's the procedure...
First go shopping. I bought 2m of 10mm clear (so you can see the fluid running) plastic tube, 2m of 17mm clear plastic tube and a fresh funnel to fit the larger tube from a hardware shop. I tried to buy a 20L drum of Castrol TQ95 (this is the grade you MUST use) from Burson's but they wanted $160 for the drum, where 5 x 4L cartons cost $127. Go figure. I also purchased a generic trans filter and gasket kit – part TFK85. Supa cheap have a range of them for around $15 but all I could find were TH700, BW40, BW35 and C4. None of the staff knew what a BTR95 was and they didn’t even have a book on the filter kit part numbers. You might be luckier than me but I bought mine from Burson’s at $39. The kit has a rectangular black rubber gasket and a very large plastic filter.
Back at home I had the car up on ramps and stands. It is important that you have it fairly level. I suggest you do not do this when the car is hot – it burns! First I dropped the cooler return line off the external cooler. Yours might not have an external cooler, but the flow is from bottom to top through the radiator cooler, found on the battery side of the radiator, and you can tap in here. You will have to follow the plumbing if you have an external cooler. You’ll soon know if you get it wrong – trans fluid everywhere. I attached the 10mm tube to the external cooler outlet as it was easiest to get at. Thus the fluid would be flowing through both coolers and then out the tube. I ran the tube into an empty 4l oil carton - one with the clear measure down the back so I could see and measure how much fluid was coming out. I ran the engine to pump the sump out until the fluid just stopped flowing (took less than 30 seconds). Should be 3.5 to 4l. I did this first step to make it easier to remove the trans sump (ie - so it wasn't full). The fluid that came out of mine was ‘sump oil black’!
Next I removed all but the front couple of bolts from the transmission pan, and with a catch tray under the back I cracked the front bolts slightly to drop the pan and allow the remaining fluid to drain. Once empty I completely removed the pan. The old filter will be obvious. It has a metal retaining clip across the bottom which should come off from the drivers side with a nudge at it’s side with some pliers. Be gentle and don’t bend or break it. Pull the filter down with a bit of a twisting motion and it should come free. Make sure you get the rubber grommet out of the fitting with it as you should have a new one to fit with the kit. I then left the tranny to drain for a bit while I washed out the pan with degreaser, water, and then compressed air to dry. Mine had some nice bits of metal in it - ouch. I also cleaned around the mating surface on the transmission with a soft rag. Resist the temptation to wipe the internals as you will only cover them in lint.
Cleanliness is very important here so be careful that you don’t pick up any foreign particles as you refit the filter and pan. Make sure the filter has the new grommet fitted and push it up snug into the fitting. It should sit fairly flush on top of all the solenoids. Refit the clip and then the sump with the new gasket. Make sure it is all spotlessly clean. Torque spec for the bolts is 4.5Nm.
Now on the later boxes (EL onwards I think) there is no transmission dipstick, just a plug up the side of the case near the exhaust mount on the drivers side. It takes a 16mm ring spanner. Remove it and clean the crudd off the end (it has a magnet). If you have a transmission dipstick in yours, you are going to refill it through that tube. If you do not know the difference between the transmission dipstick and the engine sump dipstick, stop reading this now. In my case I used the 17mm hose and routed it from the hole, up across the top of the cat and out near the brake master cylinder in the engine bay. I cut it to length and then fitted the new funnel and cable tied it to the master cylinder in a convenient position. This tube and funnel must be clean. First I poured in about 4l of fluid, then started the motor with the trans in neutral until the filter and pump primed and we had fluid flow again.
You will need some help for this next bit... From now on you need to try and keep pouring in as much fluid as you pump out. If you are filling via the trans dipstick you will have trouble keeping up with the out flow as the tube is thin. Using the plastic tube, I was able to keep up with the flow - just. With one person starting and stopping the motor, I kept pouring in fluid as it pumped it out. Never let it get more than 2 litres ahead of what you pour in. Thus you will need to keep starting and stopping the motor. The aim here is to keep pouring this expensive fluid in until what comes out the cooler line is the same colour as what you are pouring in. Also - you should not run the pump dry for any length of time.
In my case 20l was not quite enough to bring the fluid back to perfect colour, but it was fairly close. You need to make sure that you put the same amount of fluid back in as you have taken out, so I used all the empty containers to collect and measure the old fluid.
Once done you have to put all the cooler lines back to normal and then check the fluid level. There is a section in the back of the car manual that explains this procedure. Follow it to the letter as an overfill can cause damage to the pump seal when the fluid expands with heat. Essentially you have to get the box warm from a short drive, but not hot, and make sure that the fluid is level with the filler hole. Dipstick equipped cars – I am not sure of the procedure but read the manual – or at least what it says on the dipstick.
If you have the BTR85LE (ED and earlier I think) you can also adjust the bands should you be game. There is a section in the Gregory’s manual on this procedure. Later boxes can't be adjusted.
In my case the complete flush sorted out a lot of the shifting problems, but I know that this box probably won’t last that long under these conditions. Next step for me is to fit a decent size cooler. Supa Cheap had aluminium ones that was about 3 times the size of the Ford one, for $99. But first I am going to try and find the condenser core out of an old wall air-conditioner unit and see if it will fit / has the right size lines. I am told that these make good coolers due to their size. A fan might also help.
I offer the above simply from my experience and a bit of research. If what I wrote doesn't make a whole lot of sense to you then I suggest you don't attempt it. Also, please do not hold me liable for any damage you do to your transmission. In my case the above worked, but not being an expert on BTR boxes I cannot be sure that this is entirely safe either. A rebuild on one of these runs to $2000 +.
Through research I have found out that theses transmissions, although one of the nicest shifting 4 speeds around, are fairly marginal in capacity. Once stressed with some hard driving and / or towing they have a propensity to overheat, burn fluid and then cause all sorts of problems like clutch pack and band burn up, cooked solenoids, burning of nylon balls in the valve body and even breakages of major gear-set components. Keep them cool and keep the fluid fresh seems to be the key to keeping them happy.
And the Ford factory manual says that these boxes are sealed for life!
Cheers - Pat Sproule