Piston Slap: Not Exactly a Rugged Mountaineer Edition
TTAC Commentator NN writes:
My wife’s 04 Mercury Mountaineer (V6, AWD) recently hit 65k miles. The transmission had been clunking around noticeably lately, and I realized that:
a) These trannies are prone to fail
b) We hadn’t yet changed the ATF on the vehicle.
I am aware of the argument that some people make that when tranny fluid is old not to change it because the varnish build up, etc. helps to hold things together. But I thought 65k was still pretty young so I told my wife to take it in and get the fluid changed. She took it to a local non-franchise, non-dealer mechanic–just a fluid change and flush, no filter change as the mechanic said it wasn’t needed. The very next day the “O/D Off” light starts flashing constantly, which suggests that the transmission needs service. This is the first time we have seen this light.
My first thought is to make sure the mechanic did everything right on their end…i.e. didn’t leave the fluid level too low, etc. But in the end, I think this transmission is shot…as noted prior, it clunks in and out of reverse (with a delay usually), runs the RPM’s up during shifts like a slipping manual would, and clunks hard into neutral when coasting to a stop, also. My guess is that we are a textbook case of the last bits of the tranny holding out with the old fluid, and the flush was the end of it. The car, otherwise, is well liked…and paid off.
My question for you is what to do if the tranmission is indeed in need of service. I have read on other forums about how some fixes (solenoids, etc.) can run up to $1,000 and only solve the problem for a few months. Should I just pony up the $2k for a rebuild and hope that will last for another 5 years, or should we consider dumping the car? These Mountaineers/Explorers have a history of this transmission failing so I don’t want to play around and want to get to the bottom of solving the problem quick…this is my wife’s car, after all.
Sajeev Replies:
NN, if nothing changed since you emailed me, your nightmare scenario is not very likely. Most importantly, make no judgments until you find the error code that created the warning light! This is just as true for transmissions, especially with electronic 4WD systems with far more electronic stuff than yesteryear’s trucks and SUVs.
The only fly in the ointment is access to a transmission code scanner: sometimes you need to get a more sophisticated computer scanner than what’s normally offered. Luckily, with a $100-ish deposit, you can rent the correct scanner from many parts stores. So do just that, or get the codes from the mechanic.
Again the codes are crucial: don’t listen to the mechanics diagnosis, ask him for the code and the diagnostic tree followed to come to their conclusion. Like the Grand Marquis recently discussed (http://www.thetruthaboutcars.com/piston-slap-friction-modification-for-the-mighty-mighty-marquis/) a bottle of LubeGuard Red might be the only thing needed. I’d throw a bottle in right now, and see if anything changes.
(Send your queries to mehta@ttac.com)
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I had a 2004 Explorer XLT (4WD V6) with this same transmission (5R55-). In four years and 92,000 miles, it never gave me any trouble. My sister is driving it now, with just over 150,000 miles at this point and the tranny still works perfectly! I changed the fluid and filter every 30k when I owned it...and my sister has allegedly done the same! Maybe that's how I/we managed to dodge this bullet? Now I have a 2007 Explorer (2WD, Eddie Bauer, V6) with the same basic transmission...but I haven't heard of many issues with it in '06 and newer models. I just passed 100,000 miles and no signs of trouble, but they're all highway miles. It has spent 99% of those miles cruising in O/D (5th) gear, which is far less stressful than stop-and-go driving. Or maybe I've just been very lucky when it comes to transmissions! =) My mom's old '95 Jeep Grand Cherokee (4.0L, 2WD) is sitting in my garage with 205k on the godawful 42RE transmission that failed in every other JGC except this one! My mechanic thinks it has lasted so long because the Jeep came with the optional Heavy-Duty Towing Packing. That included beefed a beefed-up cooling system and power steering pump AND an auxiliary transmission oil cooler. That may be why it's still working after 15 years and 200k miles when others a large percentage of them failed during the original warranty period!
Had a 2001 Taurus that lasted about 89k miles before the tranny started to go out. Changed fluid/filter regularly even though it's a pain in the ass on these cars and it still started to have problems slipping. After the $1800 quote to repair it we traded in the car instead of fighting with it. A lot of other small things started to go wrong at the same time. Plastic valve covers leaking, coolant reservoir cracked, alternator went bad (they must be made of solid gold at over $300 for a new one), etc... At the same time I had a manual Ranger that went over 200k miles without ever changing the fluid and my cousin still drives it. Never had an issue other than clutches. By the same token, I have a 98 Rodeo that has been used and abused off road and as a daily driver. I have over 200k miles on it and changed the tranny fluid twice. Recently it started slipping and shifting really poorly but when you would turn it off and back on it would be fine. After reading some owner boards I found out it was a dirty gear position sensor. Took it off and cleaned it and now it runs like new again. It's never been a smooth transmission, even new, but it sure has been a trooper. The only stupid thing about it is there isn't a dip stick. There is a drain bolt, and and check bolt, you just add fluid in the check hole till it spills out. It's messy and ridiculous, but the tranny has held up. The shop manual is one that tells you not to change the tranny fluid at all unless used for heavy towing.