My wife got an Explorer, '99, 5.0, all wheel drive, automatic 4R70W with a lot of miles. It looks and runs great except for the transmission hunting between 45 and 55. I told her to lock out the OD except for freeway driving. Is there anything we should look out for in the vehicle? Thanks.

 

The 5.0L and the 4-speed automatic are pretty stout items, not really a lot of things to look out for there. I had a 2000 Mountaineer with the same engine, transmission, and AWD and really the only problem I had with it was a MAF sensor that went intermittent and rust behind the running boards below the rear doors.

The first thing I'd suggest checking for the transmission hunting is the condition and level of the transmission fluid. Actually, with a lot of miles and I'm guessing an unknown history, you might as well have the transmission fluid and filter changed. Don't let someone upsell you to a transmission flush, that would be likely to lead to more transmission issues, just the standard drain, filter, and refill. See if that helps with the hunting. It wouldn't be a bad idea to change the fluid in the transfer case and front and rear differentials since these often seem to get ignored. They won't help with the possible transmission issues, but could help reduce future issues.

Does the engine idle smoothly and run great otherwise? The reason I ask is because if there is a misfire or vacuum leak somewhere it could cause the PCM to command the transmission to change gears based on perceived engine loading.

-Rod

 

Thanks for the reply. We got it from a relative that bought it new, treated it like his baby and gave me a thick book of all receipts. The transmission fluid has been changed recently and it idles extremely smooth. The transfer case and differentials have been checked but not changed. It's a FL car but was in a garage all it's life but I'll check for rust. Did yours have the gas mileage computer screen between the seats? If it did, how accurate is it?

 

contrats on the new ride!

my 2000 has been the most reliable vehicle i've ever owned to date. other than regular maintenance, the only repairs i can remember is a bad u-joint, leaking pinion seal at the rear diff, leaking oil pressure sending unit (3 times!!!) and a leaking roof rack.

i think that's a pretty short list for a vehicle with 160k on the clock.... at least to me they are all pretty minor.

all of that being said, i think i've got some ball joints going out now, and i think there is something going on with the viscous clutch in the transfer case. but ... i live on gravel, and have wheeled it off road while hunting in the hills, and towed stuff i probably shouldn't have so that can be a little hard on stuff.

not much to look out for drivetrain wise, other than the clutch in the transfer case. the 5.0 w/4r70w is likely the most reliable drivetrain ever put in the explorer.

 

The last I knew those gas mileage read-outs are mostly based on engine vacuum....the more you lean on the pedal it merely changes the calculation. Nothing compares to the fill-up and do-the-math method.

 

You mean there's no flow meter, it only guesses?

 

Thats correct, but it IS an educated guess....the more you lean on the pedal, the worse the gas mileage is in actuality.

 

With my scan tool I was able to monitor flow and fuel level, so there's not reason the fuel computer could not use those signals to calculate fuel economy. I don't think I ever calculated it manually. Considering that the trip computer on my 2000 displayed how many gallons of fuel remained, I suspect it used the flow to calculate fuel economy.

-Rod

 

Re: Transmission chattering. My transmission guy said to add friction modifier, skunk oil, to the trans. "90% of the time this takes care of the problem", he said. I just did this and will report on the outcome.

 

i would change that to read:

"90% of the time this hides the problem"

friction modifiers can mask clutch problems, but the problem will still exist.

if there is a mechanical problem, there is no compound in a bottle that will fix it.

out of curiousity, how many miles are on it?

 

244k. What do you mean mask? As I heard it's the lockup converter going in and out of lockup at around 50 mph.

 

i'm far from a transmission expert.

as i understand it, the clutches get damaged (i heard them described as brittle) when the fluid wears out. So, if the clutch chatter is being caused by clutches that are damaged in a physical way, then there is nothing you can do to "fix" it, at least not with a bottle.

friction modifiers will mask the problem and allow the clutches to slip without chattering. the chattering is a side effect, not the root problem.

new fluid may help. it did on mine. but if your fluid is already new, then then it may be chasing good money after bad.

if you have receipts, it would be good to check what was done. a simple filter change and 4 new quarts of fluid will usually help for a short time with the chattering to return shortly after. the ONLY thing that will help is a full fluid exchange. Mercon V at a minimum (mercon V is now the recommended fluid for all applications which originally called for Mercon http://www.drive9.com/wp-content/upl...1/06-14-04.pdf). assuming the fluid has not been exchanged, i'd go with full synthetic.

do not have it flushed with chemicals. just go someplace that can exchange it. plan on 14 quarts if the fluid isn't too dirty, plan on a couple more if it is pretty dirty (i think they used 16 quarts on mine to make sure all of the old fluid was exchanged). You can do it yourself in the driveway if you are handy. the Torque converter should have a drain on it allowing you to drain the converter and pan. alternatively, you can disconnect the cooler return line and do it about 4 quarts at a time.

here's a good thread about it:
https://www.ford-trucks.com/forums/1...ing-issue.html
there are lots of other threads saying to use the friction modifier, however i would default to Mark Kovalsky's advice

here's the step by step process:
Changing ATF Fluid in a E4OD and 4R100 transmission .: Articles

that's about the extent of my knowledge and experience. I exchanged the fluid in mine at about 110k miles with full synthetic. the previous owner exchanged it at about 77k with merc plus a modifier. merc V or a full synthetic is the right way to do it, IMO.

good luck!

 

you do have the most reliable drive-train ever put into the explorer. good luck with it, most are minor issues. i love my 5.0 explorers!