2000 Mountaineer - Whine on acceleration - Quiet as a mouse on deceler

[pjfsail]

Hi, my name is Peter I spent the first part of my mechanical career as a Heavy Duty Mechanic focusing my attention on earth moving equipment. I worked my way up through the traditional ranks working on every piece of equipment that would appear on a normal dam building job site, Interstate Highway build or in the shop. I eventually worked for a Caterpillar Tractor Dealer as a Field Service Mechanic. I didn't spend much time working on cars or pickup trucks. So, when I work on one of my vehicles I transfer my skills. In regards to automobiles I ask lots of questions. So, here goes with 2 questions.

I recently bought a 2000 Mountaineer (Love it) with 200,000 miles on the clock. The SUV that the Mountaineer replaced was a 1987 Toyota 4Runner with over 300,000 miles. There are very few problems with the Mountaineer but I am concerned about a WHINE ON ACCELERATION and quiet as a mouse on deceleration. So, I decided to drain oils and replace them as a starting point. I drained the TRANSFER CASE and noticed that it was overfull, the oil was black, but did not smell bad. I drained the REAR DIFFERENTIAL, the oil looked ok, did not smell bad so I cleaned up the nasty stuff on the inside of the cover, with a long screw driver I poked around looking at backlash and seeing if anything appeared to be problematic, didn't see anything wrong.

I'm ready to replace the oils. The tag on the differential says to use ONLY 85 -140 SYNTHETIC. I have read to disregard this directive and to use 85 - 140 and add Ford's Friction Modifier. The other tag on the differential indicates it is a Limited Slip Differential. Of course, I want to add the correct oil but what is correct? I have two questions 1. What oil do I use? 2. Has anyone else experienced the whine on acceleration and what did you do about it?

 

[Rick]

The transmission pump could be causing a whine. I have heard that before. The whine is not coming from the speakers, right?

Not sure on the diff fluid for your year Explorer. You may want to post in this forum where the right folks should see the post:
Stock 2002 - 2005 Explorers

 

[RangerX]

Moved it for ya. Welcome to the forum!

 

[pjfsail]

Hey, thanks for the quick replys. So, is a 2000 Mountaineer more like a 2002 - 2005 Explorer than a 2000 Explorer?

 

[Rick]

Hey, thanks for the quick replys. So, is a 2000 Mountaineer more like a 2002 - 2005 Explorer than a 2000 Explorer?

LOL, I was reading the year of your vehicle off of your profile which said 2005.

The 2000 Mountaineer is basically the same as the 2000 Explorer. I moved the thread to the Stock 1995-2000 forum.

 

[pjfsail]

Thanks for putting my post in the right place.

 

[Collin Whitfield]

Use a good synthetic 85w-140 gear oil, if that's what the tag on the case says, and also add the friction modifier to it. The friction modifier is what is required for limited-slip rear ends and allows the clutch pack to work correctly. I have a 1999 5.0 Explorer and it uses 75w-140, with added friction modifier as well, but the grades could have changed the next year.

If you're doing the front axle as well, it should use 80w-90 axle lube.

 

[koda2000]

A “howl or whine” during acceleration over a small or large speedrange is usually caused by worn ring and pinion gears or improper gear set up.

 

[pjfsail]

A “howl or whine” during acceleration over a small or large speedrange is usually caused by worn ring and pinion gears or improper gear set up.

This is what I thought. I've done a considerable amount of research, asking questions, looking up information, chasing down leads etc. The thing I found out is that a number of folks with Explorer's and Mountaineers complain of the same or similar problem. My question, how can this be?

 

[pjfsail]

Use a good synthetic 85w-140 gear oil, if that's what the tag on the case says, and also add the friction modifier to it. The friction modifier is what is required for limited-slip rear ends and allows the clutch pack to work correctly. I have a 1999 5.0 Explorer and it uses 75w-140, with added friction modifier as well, but the grades could have changed the next year.

If you're doing the front axle as well, it should use 80w-90 axle lube.

 

[koda2000]

This is what I thought. I've done a considerable amount of research, asking questions, looking up information, chasing down leads etc. The thing I found out is that a number of folks with Explorer's and Mountaineers complain of the same or similar problem. My question, how can this be?

The usual causes I suppose... wear and lack of maintenance. You did say it has 200,000 miles on it, right?

 

[fast_dave]

The transmission pump could be causing a whine.

I was also thinking the same...

BUT NOTE: For this to be the case (bad pump) when the engine is running, and the Ex is standing still, the pump should still whine both in Park as well as Neutral.

To add - based on that there is no mention of the FRONT DIFF in your original post, I will add the following observation...

On 2nd Generation 4X4 Explorers/Mountaineers, the FRONT DIFFERENTIAL is the one that usually doesn't get serviced because the front cover can't be EASILY removed. All sorts of stuff is in the way that prevents the front diff cover from coming off short of unbolting & lowering the entire front axle housing - a really BIG job and something the 99 percentile will not do.

Without removing the front cover, to drain and fill the front diff, you have to do BOTH operations through the fill hole with first a suction pump. and then with a fill pump. In this case, the 80 percentile will not do this, it's about a two hour operation with a hand pump... I've done it this way every 50,000 miles and it's a PITA (but a necessary PITA).

Best time for this is during the summer as it's easier to move the high viscosity fluids.

Diff Fluid: I use Redline Synthetic or Mobil Synthetic 75-140 front & rear with no modifiers.

 

[pjfsail]

I was also thinking the same...

BUT NOTE: For this to be the case (bad pump) when the engine is running, and the Ex is standing still, the pump should still whine both in Park as well as Neutral.

To add - based on that there is no mention of the FRONT DIFF in your original post, I will add the following observation...

On 2nd Generation 4X4 Explorers/Mountaineers, the FRONT DIFFERENTIAL is the one that usually doesn't get serviced because the front cover can't be EASILY removed. All sorts of stuff is in the way that prevents the front diff cover from coming off short of unbolting & lowering the entire front axle housing - a really BIG job and something the 99 percentile will not do.

Without removing the front cover, to drain and fill the front diff, you have to do BOTH operations through the fill hole with first a suction pump. and then with a fill pump. In this case, the 80 percentile will not do this, it's about a two hour operation with a hand pump... I've done it this way every 50,000 miles and it's a PITA (but a necessary PITA).

Best time for this is during the summer as it's easier to move the high viscosity fluids.
Diff Fluid: I use Redline Synthetic or Mobil Synthetic 75-140 front & rear with no modifiers.

Thanks for the important information. I started at the rear because the sounds seems like it is coming from the rear. I will work on checking the noise from the transmission pump. I have both oils and the modifier I just wanted confirmation on what oil to use. I drained the transfer case and what is left is the transmission, engine, and the front differential. I'm prepared for the rear differential, thanks!

Yes, it has 200,000 miles on it and I don't expect it to be free of every noise. I'm the kind of person who asks questions looking for advise of folks who know. I read in another Ford forum to try using 75-140 with the Ford modifier. Well, immediately I'm looking for an answer that tells me why should I ignore the label on the housing? What you are telling me to do is to follow the information on the label. I follow advise if it is presented logically from a person who shows him or her self to be well informed. Thank you for taking the time for the advice.

 

[GLOCKer]

I had the same issue. I bought a bearing kit for the rebuild of my rear diff. and it worked out beautiful! My ring and pinion were in great shape but the pinion bearings were scored. Replaced all of the bearings, refilled with Royal Purple with the Ford Friction Modifier and it is PERFECT!

 

[koda2000]

@pjfsail If you compare Ford's recommended lubricant/oil specs over time (say 1995-2001) you will find many of them changed. This is not because the parts requiring lubrication have changed, but because better lubricants were developed. In some instances the old oils are not even available anymore because they are superseded by the newer oils. For example Mercon ATF was later superseded by Mercon V. A 1995 owner's manual my say to use Mercon in the transmission, but Mercon V is the current spec. Similarly for your rear diff, current recommended spec is 75W140 full synthetic hypoid gear oil (with Motorcraft friction modifier if LSD) but older vehicles might have been spec'ed for 80W90 conventional hypoid gear oil. By going by the current spec you use lubricants which offer the best protection. You don't gain anything by using the older spec lubricants (assuming they still available).

The upside is better protection against wear and usually increased change intervals. The downside is the synthetic lubricants cost more. If the older products are still available the choice is yours.

 

[donalds]

Sounds like carrier and pinion barring s to me
May as well do the axle barring s to

 

[skpyle]

Hello pjfsail, I have a question that is not necessarily related to your whine, but could point to an impending problem. Does your Mountaineer have a 5.0L V-8 engine? If so, you have AWD and the Borg Warner 4404 single speed transfer case. You mentioned the transfer case oil was overful and black. That could be an indication that the viscous coupling has failed inside. What did you refill the transfer case with? Manual calls for MERCON ATF, not the same MERCON V that the 4R70W transmission takes.
Might be worth changing the transfer case fluid a couple of times with store brand Dexron III/Mercon ATF and see if it clears up.
That will do nothing for you if the viscous coupling has failed, but fresh fluid will be good if it hasn't.

 

[pjfsail]

Use a good synthetic 85w-140 gear oil, if that's what the tag on the case says, and also add the friction modifier to it. The friction modifier is what is required for limited-slip rear ends and allows the clutch pack to work correctly. I have a 1999 5.0 Explorer and it uses 75w-140, with added friction modifier as well, but the grades could have changed the next year.

If you're doing the front axle as well, it should use 80w-90 axle lube.

I was also thinking the same...

BUT NOTE: For this to be the case (bad pump) when the engine is running, and the Ex is standing still, the pump should still whine both in Park as well as Neutral.

To add - based on that there is no mention of the FRONT DIFF in your original post, I will add the following observation...

On 2nd Generation 4X4 Explorers/Mountaineers, the FRONT DIFFERENTIAL is the one that usually doesn't get serviced because the front cover can't be EASILY removed. All sorts of stuff is in the way that prevents the front diff cover from coming off short of unbolting & lowering the entire front axle housing - a really BIG job and something the 99 percentile will not do.

Without removing the front cover, to drain and fill the front diff, you have to do BOTH operations through the fill hole with first a suction pump. and then with a fill pump. In this case, the 80 percentile will not do this, it's about a two hour operation with a hand pump... I've done it this way every 50,000 miles and it's a PITA (but a necessary PITA).

Best time for this is during the summer as it's easier to move the high viscosity fluids.

Diff Fluid: I use Redline Synthetic or Mobil Synthetic 75-140 front & rear with no modifiers.

One of the members of the forum suggested adding Ford's Friction Modifier to the 75 -140w Synthetic Oil. I have a limited slip differential according to a tag bolted to the differential cover, is this a good idea? I thought the friction modifier was only used with NON synthetic gear oil. I am determined to get to the bottom of this. I'm just the kind of person who wants to know.

 

[koda2000]

Look, you should use 75W140 full synthetic hypoid gear oil and with limited slip you should also use the Motorcraft friction modifier. Period.

The friction modifier prevents the LSD clutches from chattering. IDK if the friction modifier would be required with a non synthetic gear oil and I don't feel like researching it for you. You can Google this as well as I can.

 

[imp]

@pjfsail
Whine on acceleration only is almost certainly originating with the ring and pinion. Transmission pumps work at constant load, more or less, and have nothing to do with whether power is being transmitted or not. Pinion bearings which are bad can make lots of whining noise, but that noise is unaffected by transmission of power, IOW, acceleration or deceleration. Pinion bearings badly worn WILL allow misalignment of the gears, and CAN cause whine upon acceleration, because the forces trying to pry the gear teeth apart are high when accelerating, but very low when decelerating.

First order of the day would be to inspect the ring gear teeth. If shiny and bright, no scoring, galling, or dull-looking appearance, pinion bearings OR differential side bearings would be needed. imp