History; 2002 Mercury Mountaineer AWD V8 manuf. date 09/01 117K. I seen to get conflicting answers on weather or not it's a 5R55S or 6R60 trans. Anyway, when starting out it seems to slip in a lower gear upon shifting, the rpms go up and if you let off the gas it will shift. Lets say in the 10 to 20 mph range. Once past this it works fine. Can get on the highway go 30, 40 miles no problem. Get off the highway, stop, then start out again and the check transmission message comes on and the over drive light flashes. After a few seconds the message goes out, not the o/d light. Pull over shut car off, restart, everything ok. Checked for codes, none. Looked at outside of tranny, no leaks. I would appreciate any input, the only thing I know about a/t's is how to change them. Hopefully I won't be doing that with this one. Thanks in advance for any advice, this forum is a great source of info for Ford products.

 

The 5R55S only came behind the 4.0L.

 

the 5R55 is a 5 speed auto trans. It is electronic shift, uses a series of solenoids. small particles of crap can cause the solenoids to drag or hang up. I believe it is a good idea to change out the original oil at 30 K miles, and again at 90-100K miles. That gets rid of the crud and wear materials that cause things to stick. Has the oil ever been changed?

 

https://www.ford-trucks.com/forums/588191-5r55.html

 

No I've never done anything to it. I talked to the service guy at the local dealer and at first he suggested a flush, but after I told him the check transmission message comes on he said a flush probably woulden't do any good there was more than likely already something wrong with it. I'm taking it in friday for an unrelated recall maybe they can test something? I do all my own work and the dealer scares the crap out of me, but with a tranny I don't have too many options.

 

Its hard telling if its too late or not. You can pull the transmission pan, clean all the metalic sediment off of the pan and valve, change the filter and reinstall. You will have removed about 5 quarts of oil by pulling the pan. There is not refill tube, You need to pump 5 quarts up into the transmission thru the drain plug, It has a stand tube inside the drain plug. I use a weed sprayer and fill with MERCON V. WOuld be best to change out all 13 quarts, but you would need to remove a line to the radiator/ cooler and pump it out to do that. You could do the 5 quarts and get and idea if that helps. I do the 5 quarts about every other year.

 

Hey steve(ill). I am talking on another post about transmission service. I have a 2002 Mountaineer 4.0L V6 96K miles, I jsut bought it and previous owner took real good care of it, records of all the services done. It seems he had the trans flushed atleast twice at a Ford dealer. As far as self maintaining the tranny, is it more beneficial to have a shop do a complete fluid exchange with a machine or drop the pan change the filter and refill it myself? Another question about your weed sprayer idea, youre talkin about a pump jug with the spray wand correct?

 

When a transmission is working, there is steel "dust" that falls off and forms sediment in various corners of the transmission. most of it sets on the bottom of the pan and in various crevices in the transmission. some of the lighter stuff stays in suspension in the oil. If the factory does a "flush" they may use a pressureized system that stirs up some of the crud in the crevices and lets it wander around the system. you can get that stuff stuck into valve spools. SOME guys dont like a pressure flush done, i happen to be one of them. I prefer to remove the pan, drain the oil, change the filter, wash out the pan and wipe off the valve body to get all the sediment off that you can see. If the oil looks half way decent and you do this every 30-50k miles, you dont have to change all 13 quarts, you can do just the 5 in the pan. If you have never had an oil change or got massive crud, you might want to remove a cooler line to the radiator and drain more of the oil out. THe torque converter holds about 7-8 quarts and you have to run the motor to pump it out. normally put one of the cooler lines in a bucket, put new oil in the trans, start and run 60 seconds and let the pump push all the old oil out of the converter into the bucket... repeat, etc... The new transmission has no dip stick. THe drain plug looks like a 1 inch plug with a 1/4 inch pipe plug in the center. When you remove the drain plug you will see there is a 2 inch tall tube on it with the 1/8 inch pipe plug type thing under it. After installing the pan, you put 5 quarts of oil into a regular weed sprayer, pump up and shoot it up the 1/4 inch pipe plug hole into the trans. When its full to the top of the 2 inch tube the oil will start to run backward toward your weed sprayer. When it appears full, i put 1/2 quart extra in, "just in case" and plug it. Use MERCON V oil. In theory, you should run a few miles to warm up the oil, then pull the 1/4 type pipe plug and see if the oil starts to run out. Let a couple spoonfulls flow. If it keeps coming, its full, if it quits, add more.

 

go to the link, and click on the photo icons.

Ford 5R55N transmission

 

Wow, thank you so much for all the helpful info. Got another tranny question for ya though. Ok, so I have my foot on the brake and go from Park OR Reverse into Drive and let my foot off the brake it feels almost like it "slams" into gear. I dont like the word slam but you can feel it and hear it go into gear kind of hard. It runs good shifts smooth and all, its just when you put the tranny into drive and let off the brake Im curious if that is an issue i need to be worried about. Again, thank you for the info the whole power flushing idea makes since, im gonna go with dropping the pan like you suggest. The link with the pictures, there seems to be a fill plug on the rear end of the tranny, use it or no?

 

Well just got back from the tranny shop. Get ready to bend over. Transmission is a 5R55 (2002 Mercury Mountaineer V8 AWD). Old guy was real helpful, they have had many problems with these models, different things over the years. He said best to replace the unit with a used one or rebuilt one. Many of the cases are worn out and can't be repaired. So far I've checked in a 100 mile radius and found the following: used 825 (112K), 900 (112K), 1250 (about the same) and rebuilt 1500 & 1800. Tranny shop wanted 25 or 2600 to replace mine with a rebuilt. I'm going to do it myself just trying to decide which way to go. Will post the results when done.

 

yours has got 117k miles, they tell you the case is worn out, and suggest you buy a USED unit wit 112k miles?????? LIke i said, its the steel crud from the parts wear. It floats around and causes some abrasion and can cause spools to stick. The aluminum bores for spools can get sloopy due to the abrasion from contaminated oil. Best idea is to keep changing it to keep it clean.. There is also a kit you can buy to repair the bore.. see if i can find that. Its a good trans if you can keep it cleaned!!

 

here is one discussion about a gasket that can leak and cause poor pressure. there is a second problem that i have heard of piston bore wear and loss of pressure... i have had neither in 120k miles, but i have changed fluid 3 times.

https://www.ford-trucks.com/forums/588191-5r55.html

to KB, yes, you can use the fill plug if you can get to it... there is no prayer of getting to it on a 2002 4 x 4, i can tell you that.. Thats why they use the pump.

 

Had to have the trans rebuilt at 63K miles in my 02 mountaineer to correct the slip between 2nd and 3rd and 3rd to 4th. They press a brass sleeve into the servo bores to correct the problem. I had them replace everything in the trans including a new heavy duty torque convertor so it cost me 3K but have had no problems since. Fluid looked very good just before I stated having problems.

 

Steve I think you're right it wouldn't make much sense to replace my tranny with another used one. I'm afraid 6 months down the road I'll be in the same boat. I've been reading all weekend and there are a tremendous amount of problems with these trannys especially 2002. Mine set a code today 745. People fix one problem and something else pops up weeks or months later. A real money pit situation. I can get a reman w/new torque converter for 1925.00 and it comes with a 3 yr. 100k warranty. I'm going to keep the Mountaineer it beats buying something new so it makes sense I get something with a warranty to cover my *** for a little while anyway. Maybe the rebuilders have replaced some of the common faults. I guess I can only hope.