Humming/whining noise in rearend

[Lovemy98ranger]

I just bought an 02 ranger 4.0 with 58k miles a few days ago. The Test drive seemed fine, I didn’t take it on the highway. So I Drive it home on the highway, and noticed a little hop in the rear, no big deal. I noticed the diff cover was wet, but it was a rainy day. I drove it the next 2 days and it starting whining from the rear, like its coming from the differential maybe. When I looked under it today after my ride home and the whining noise, I noticed it dripping oil
From the differential cover gasket. Would it whine if it was low on oil only? Or is there something damaged for sure? And also, after coming from Autozone looking for a cover, I noticed my fill bolt, it is all rusted up to the point that I don’t think I can loosen it up, the hex is almost unseen on the bolt. I’m guessing I have to get an aftermarket differential cover that has a drain/fill bolt in the cover. Almost wishing I never bought this truck. The body looks mint and the low miles got me. It does have rust underneath, but no damage, holes, or cracks in the frame. Is the bolt removable? Or should I not
Bother and buy an aftermarket cover with built in fill bolt?

 

[4.0blue98]

I'd have a go at the fill plug ASAP. Spray it with some penetrating oil and let it sit a bit. You may be surprised. You've got nothing to lose by trying. Hopefully its just low on oil and you haven't damaged anything but need to sort it right away. I've never had mine low but I've had another vehicle that did whine when it got low. That one wasn't damaged but had a leak like yours.

 

[Dirtman]

There's no pressure in the differential so all you need to do is drill a 1/2" or so hole in the cover at the proper height and stick a rubber plug in it to make a new fill port. There's also no gasket on the diff cover (from the factory) and I dont recommend using one. Black RTV is all you need. Go get 2 quarts of fluid, some black rtv, and a rubber plug and get that thing fixed asap.

 

[Lovemy98ranger]

I'd have a go at the fill plug ASAP. Spray it with some penetrating oil and let it sit a bit. You may be surprised. You've got nothing to lose by trying. Hopefully its just low on oil and you haven't damaged anything but need to sort it right away. I've never had mine low but I've had another vehicle that did whine when it got low. That one wasn't damaged but had a leak like yours.

The bolt has the square style head, but it’s an “innie, not an outie” if that makes sense. Basically supposed to be able to fit the end of a ratchet or the extension into it, (like my 05 mustang). I’m afraid it’ll strip it almost instantly (not the threades but the square itself). Should I apply some heat to it first, or will that make it strip faster? I have a 2 post lift at home, although I’m not a mechanic by trade ( a machinist) but a mechanic by necessity. This is my second ranger, also have a 98 with 57k on it now. Love it so much that I bought another, this one. I’m keeping my fingers crossed, see if it’s just low, hopefully the noise goes away when it has the new cover and gasket. Any other tips besides soaking it with penetrating oil? I guess if I do strip it, I’ll have to get a cover with bolt anyways

 

[4.0blue98]

Exactly, you have nothing to lose. I'd skip any heat at first. You might be surprised at how sturdy that plug is. The fewer point the tougher it is to strip IMO. Like Dirtman said, no pressure so you can do the drill and plug thing too, but since the cover is leaking already it needs to come off. Cover with a plug is fine but watch the height of the plug. You really want to maintain the factory fluid level.

I just freed one from a project that had been outside for the past 40 years and inoperable for about 20 (in salty NEPA). I doubt the plug had ever been out and probably had the original whale oil in it.

 

[Uncle Gump]

I would just have at it... if it's beyond getting out... so be it. There are options.

The bigger question is where did the lube go? From what you describe someone has been fooling with it. Pinion seal? Axle seals? Probably need to give this entire situation look over. A leaky pinion seal will look like the cover gasket is leaking.

 

[Lovemy98ranger]

I would just have at it... if it's beyond getting out... so be it. There are options.

The bigger question is where did the lube go? From what you describe someone has been fooling with it. Pinion seal? Axle seals? Probably need to give this entire situation look over. A leaky pinion seal will look like the cover gasket is leaking.

The cover is rusted to the point that the oil is seeping through the metal. And it’s also leaking/dripping at the bottom where it loooks to be the seam of the cover to differential.( or just seeping through the cover so bad that it drips at the bottom) I can see that nobody has messed with it yet, all the bolts have rust and no evidence of markings from a wrench. I bought it from the original owner, 83y/o guy who used it at his seasonal property in nh. He gave me a stack of receipts for repairs over the past 17 years of ownership including front wheel bearings, neutral switch, even a bad wire that a mouse chewed. But nothing about the rear differential. I can see that it hasn’t been messed with and all original still. I’m gonna have a go ahead and try to remove the bolt first. If that doesn’t work, I’ll remove the old cover, drill a hole in the new cover trying to match the hole height, install it using black rtv or the gasket (I’ll have to find a rubber cork first that will match the hole that I’m drilling before I do anything). And also, as I was going to. It the new cover, I asked about the bolt, and they said they don’t have it and can’t get one (autozone) so if I was able to get the bolt out, I wouldn’t want to put that old beat up rusted plug bolt back in

 

[4.0blue98]

Sounds like a plan.

It's just a threaded plug. Probably match one up at Lowes or Home Depot. Plumbing section maybe. McMaster Carr online might work too.

I'm personally an RTV fan but Lube Locker makes a reusable gasket for the 8.8.

 

[Lovemy98ranger]

Sounds like a plan.

It's just a threaded plug. Probably match one up at Lowes or Home Depot. Plumbing section maybe. McMaster Carr online might work too.

I'm personally an RTV fan but Lube Locker makes a reusable gasket for the 8.8.

Do you happen to know what weight of gear oil I should use. And I know to fill it untill it comes out of the screw hole, is it approximately 2 quarts.

 

[4.0blue98]

I just got done changing mine today. I always use 80w90. I don't tow or beat on mine and I'm pretty sure that's what the FSM calls for. I use the cheap Walmart brand, always have.

 

[91stranger]

I'm dealing with a similar situation. I had a leaking pinion seal. Replaced that, removed the diff cover and only 1/4 of a quart came out. Gears look good honestly. Cleaning the diff cover I found rust holes around the lower right side.. Went to remove the fill plug and it was RUSTY and just rounded out when I tried removing so I had to drill a hole and get a rubber plug. Had to drill the hole in the upper right so the plug wouldn't hit anything and I just added the 2 quarts it called for. Still having issues getting backlash set though. I honestly don't know if it is backlash or a bad pinion bearing. I have a growling sound whenever I let off the gas above 40mph. Goes away instantly as soon as I give it gas but comes back as soon as I let off the gas. I got the pinion nut almost tightened all the way to the point of only having 1/8th of play in the pinion flange which I thought would be as good as it would get but I still have the sound and can feel it in the floorboards too. Anyone have ideas what I should be looking for? U joints are good and tight, its a one piece aluminum drive shaft, checked both front wheel bearings and they spin easily with no sounds.... Not sure what else to check.

 

[Dirtman]

To the OP its slightly less than 2 quarts, and regular old 80w90 is fine unless you have a limited slip which many rangers do have. Then you either need to use a friction modifier with it, or just use a synthetic (75w90 or 75w140) which will have the friction modifier already added.

 

[Lovemy98ranger]

ok. I swapped out the diff cover, had to drill a hole in the new cover and use an expandable rubber cork. Also used a gasket. When I removed the old cover, almost nothing came out. I cleaned up as much sludge as I could, cleaned mating surface and installed it. I put about 2-1/2 quarts of the 80/90 in it. Them took it for a quick ride around the block. Didn’t have much time for a longer ride. It was still whining, only got it up to 35-40 mph. Don’t think the whining was as bad. I’ll have to recheck the level in the morning, and take it for a longer ride. Should that whining noise have disappeared completely, or do I have to drive it enough to heat the gear oil up to work it in? All the gears inside looked good, no metal chips, and the sludge was not shiny. All the gears inside looked normal, no rounding and no grooves. Do you think the noise will go away once I drive it longer, maybe take it on the freeway and see how it sounds ? Thanks for the help, much appreciated. Next time I buy an older ranger, I definetly know what to look for now. My plan was to buy it, to resell. Maybe put a plow on it, try to get more for it, living 25 min north of Boston, plow trucks are pretty popular this time of year.

 

[Dirtman]

If almost nothing came out the wine is probably from a cooked pinion bearing.

 

[Lovemy98ranger]

If almost nothing came out the wine is probably from a cooked pinion bearing.

The thing I don’t understand is, the day I bought it, I drove it home, and it wasn’t making any noise. Drove it about 20 miles on the highway to my house. Then I probably drove it about 100 miles in the next couple days before it started making noise, and as soon as it started making noise, I stopped driving it and started asking questions here. I’ve owned it for about 5 days now. Not sure where the bearings are. I’m not a mechanic. But I did see one set on the right side, passenger side, when I removed the diff cover. I did look at it as well as the gears inside, I didn’t see any missing balls, or broken carrier, ect in that bearing I could see. I’ve never opened and inspected a rear diff, but I am a machinist, and have an idea of what things should look like, and it all looked good inside. That’s not to say that the bearings are not smoked, but I didn’t see any evidence of it being smoked