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mysterious noise


December 4, 2006
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City, State
Auburn, WA
Year, Model & Trim Level
'97 XLT 4wd
Ive had my explorer for about 8 months and been doing some work on it to get it running "good". Though there is one thing I am not sure of: about 2 months ago I noticed when I would go up a little hill around 40mph I would hear a growl/grinding noise about mid-way up the hill and then the car would downshift. I have searched through this site many times trying to see if I could find something in comparison, but no luck. If you think you might know what this might be let me know.

Background on the explorer:
1997, 4.0 SOHC, 177,000 miles, 5R55E Transmission; added 1 bottle injector cleaner to gas tank, new break pads, new front disks, cleaned IAC valve, new fuel filter, two oil changes, 30/9.5R15 tires with 65% tread / P235/75R15 studded tires with 85% tread, recharged the air conditioner with 2 cans of frion, added cb radio, and straighted front bumper.

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Hmm...could it be that its kicking into 4wheel drive on its own and with it kickin it, it would probably need to downshift because of having to push that front axle?? I should be able to feel it kick in tho. There is a couple different things that could be goin bad there....have you tried to just put it in 4Lo and go up the hill to see if it made any difference with it being in a very low gear?

Where does the noise sound like it's coming from? Trans, engine, rear end?

I think transmission. But I don't know exactly. I haven't had it happen long enough to tell. Anyone have anything I can check? Thanks for your help by the way.

Could the downshift simply be a result of going up the hill requiring more torque from a lower gear? Maybe the noise could be coming from a ujoint? Does it make any other noises from the driveline, i.e. squeaking, clicking, etc.? I would imagine if there were something going on in your transmission you would see something on your dipstick. Check your fluid level with a white paper towel and see if there's anything in there. Smell it to see if it has been getting hot. If the engine RPM raced up during this noise, then I might be a little more worried.

no no other noises, and i check my fluid every week. level is good and not burnt. What would be causing the 4x4 to kick in?

My 2000xlt does something sorta-like that. I live at the bottom of a big hill, when I have to drive up the hill (taking my daughter to school is an example of why I go up it BTW the hill is names suicide hill and is great for sledding). I believe what happens to me is predetonation on the engine about half way up the hill, then it shifts down and runs normally. When I top the hill, it shifts back up with no problems or weird behaviour. Don't know if it is what is happening to you but it happens to me.


Does yours make a noise when it down shifts?

anyone have any other thoughts? ive been reading many posts but still have not come up with any conclusions.

Update on my problem. I had my dad take a drive around the block with me to show him what Ive been hearing. He said, when we got home, I think that it is like your sisters car and you should take it in and see the ford dealer mechanic, and see what he thinks. So tomorrow I am going in to see if that is the problem. After he told me to do that we put the car up on blocks and he showed me what the "clunk" I was hearing shifting into gear, the transfer case catching the front drive shaft (yes rather noobish but Im just finally getting into working on cars, really didn't have any room to work on stuff until we moved). I will update on if I got the problem solved and/or if I need anything else. Thanks for everyones help.

Does yours make a noise when it down shifts?

No it doesn't, it shifts normally. My transmission is having problems (2nd gear has problems syncing according to my transmission guy). But when it does this I do not get any transmission error codes (O/D Off light flashing). In retrospect, the sound I get is the same sound my Chevy Silverado would make if I accidently shifted up to high like to 4 instead of 3 while excelerating. I guess it's too much gas being thrown into the engine.


Final update on my search for my mysterious noise. I took the car to the ford dealer today and they put their stethoscope on the hub bearing and that wasn't the problem. So they found the problem to be in the differential pinion bearing. I would have takin the car back from them and done the work myself but I don't have the time to do it since I leave for college on Sunday. Thanks for everyones help and for reading this thread. Im sure in months to come I will have more problems that I will need help on so I hope the help keeps coming. Thanks again.