Check your rear diff fluid level

[cj7]

My 20 Laramie 4x4 w/3.92 and limited slip, just now at around 17k, started making an occasional small binding sound when turning sharply either way. First thought it was Auto AWD or something in the front not disengaging, but determined the noise/vibe did not seem to come from the front.

Then read some posts here about the rear diffs being under-filled at the factory. So I changed the rear differential lubricant, and lo & behold, there was less than two quarts in it, when the spec calls for 2.85. It has never leaked a drop, it was driven and then left to drain perfectly level for half an hour, and I was careful collecting and measuring the drained fluid. Fluid was pretty opaque but no visible metal filings.

Refilled with Owners Manual specified MS-8985 75w-140 synthetic gear oil and the specified MS-10111 limited slip additive; would not take more than a total of ~2.7 qts. Noise/vibe gone.

PS - all you need is an 8mm hex bit socket (fill plug) and a 14mm hex bit socket (drain plug), the oil, additive and perhaps thread sealant. Oh, and a drip pan and bottle to take it to the recycling center!

 

[Whodeysrt]

Same with mine…just posted same thing 4 days ago…makes me think the gun or machine they use to fill it at factory ain’t working correctly.

 

[Eighty]

Interesting. This was a common problem with Tacomas a few years ago when I bought one (2017). For all I know it may still be a problem.

I wonder if there’s a reason they ship them low on fluid.

 

[Whodeysrt]

Interesting. This was a common problem with Tacomas a few years ago when I bought one (2017). For all I know it may still be a problem.

I wonder if there’s a reason they ship them low on fluid.

Easy to check by just taking out fill plug and if nothing drips out then it’s low

 

[wallyuwl]

Is thread sealant necessary? If so, what kind?

 

[cj7]

Is thread sealant necessary? If so, what kind?

The drain plug had thread sealant factory applied. I put some on just in case, but have heard other folks we’re fine just reinserting it as-is.

i used an oil-resistant high temp I happened to have lying around, but would imagine any oil-resistant automotive sealant/gasket maker (not threadlocker) would work.

 

[wallyuwl]

The drain plug had thread sealant factory applied. I put some on just in case, but have heard other folks we’re fine just reinserting it as-is.

i used an oil-resistant high temp I happened to have lying around, but would imagine any oil-resistant automotive sealant/gasket maker (not threadlocker) would work.

Would this work? I have some lying around from a boat motor repair a couple years ago.

https://www.fleetfarm.com/detail/permatex-high-tack-gasket-sealant/0000000241868

I also have some clear RTV 100% silicone.

https://www.fleetfarm.com/detail/j-b-weld-clear-silicone-3-oz-all-purpose-sealant-adhesive/0000000325513

I think I am going to check mine this weekend. Maybe buy some Mobil1 or Valvoline in case I need to top it off.

 

[cj7]

The silicone shown in the second link will not work.

High Tack should work, but you'd have to wait a few minutes after putting it on the threads, so that it gets thick and tacky, before you screw the plug back in. And make sure there’s none on the inside of the plug - only on the threads. If you dont apply it to the first (innermost) thread, it’s easier to keep off the inside of the plug.

If you’re going to the store to buy gear oil, consider picking up a tube of thread sealant just in case the High Tack dried out...

 

[wallyuwl]

The silicone shown in the second link will not work.

High Tack should work, but you'd have to wait a few minutes after putting it on the threads, so that it gets thick and tacky, before you screw the plug back in. And make sure there’s none on the inside of the plug - only on the threads. If you dont apply it to the first (innermost) thread, it’s easier to keep off the inside of the plug.

If you’re going to the store to buy gear oil, consider picking up a tube of thread sealant just in case the High Tack dried out...

By the time I saw this I already checked the diff fill level and used a very small amount of the RTV silicone. Put a bit on the threads, then wiped it off so only a very little bit was still on.

It was a little low. I am not sure how much, exactly. When I took the plug off it didn't leak out (had been sitting overnight). The plug is toward the front of the diff. I backed into my driveway, so theoretically the slight angle of the driveway would allow oil to start to drain out at a slightly lower fill level vs being on completely flat ground.

I put a little under half a quart of Valvoline synthetic in the easy fill bag. The nozzle made a seal when filling (didn't realize this initially), so when I took it out a bunch of oil "glugged" out. After waiting for the discharge to get to a slow trickle I put the plug back in, waited a few min, took it out and let a tiny bit more trickle out, then put the plug back. About a third of what I put in drained out in total. I think the level is pretty good now. Seems to have more pep, actually.

I ordered some high temp Permatex thread sealant from O'Reilly. I will take the plug out and put some sealant on it.

 

[cj7]

Cool. The fill plug seal is less critical than the drain. Will definitely work for a while, so no rush. When using the new sealant, do what you can to remove the silicone from both male and female threads.

 

[wallyuwl]

Cool. The fill plug seal is less critical than the drain. Will definitely work for a while, so no rush. When using the new sealant, do what you can to remove the silicone from both male and female threads.

Revisited this again today. Parked the other way, with where the fluid would go toward the back of the differential with the slight downslope. When I took the plug out no fluid came out. I put it in until it slowly trickled out. The plug and female threads were pretty clean, but I did use a pick to get out the silicone (there wasn't much). Put the thread sealant on the plug and put it in once fluid stopped seeping out. Should be good to go for the next 40k miles until I will do a full drain and fill.

 

[cj7]

Revisited this again today. Parked the other way, with where the fluid would go toward the back of the differential with the slight downslope. When I took the plug out no fluid came out. I put it in until it slowly trickled out. The plug and female threads were pretty clean, but I did use a pick to get out the silicone (there wasn't much). Put the thread sealant on the plug and put it in once fluid stopped seeping out. Should be good to go for the next 40k miles until I will do a full drain and fill.

 

[UnloosedChewtoy]

You all got me curious, so I checked mine this weekend... yup, pulled the fill plug out, and nothing started dribbling.

I planned ahead for this (for a change). Didn't want to do a full change at only 7500 miles, so I ordered a bottle of Mopar fluid (the OEM synthetic stuff). Glad to see FCA is doing full synthetic fluid in the diffs these days, as the 4th gens were not synthetic.

Topped it off, took just shy of a half a quart before she started dribbling. Reinserted fill plug, and hopefully thats the last of it until at least 30k. (I like to do maintenance a bit earlier than necessary, for peace of mind.)

Thank you all to those that alerted me about this. While it may not have made any difference, it certainly could have! Better to be safe than sorry.

 

[Kaderast]

Appreciate the heads up on this. Just checked mine today at 5,000 miles, sure enough it was about half an inch below the fill hole. Put just over a half quart in to top it off. A bit concerning something that takes as much abuse as a differential would come under filled from the factory.

Decided I might as well check the front too, it was low also. Only added maybe 15-20oz to it before it was full though.

 

[Scram1500]

You all got me curious, so I checked mine this weekend... yup, pulled the fill plug out, and nothing started dribbling.

I planned ahead for this (for a change). Didn't want to do a full change at only 7500 miles, so I ordered a bottle of Mopar fluid (the OEM synthetic stuff). Glad to see FCA is doing full synthetic fluid in the diffs these days, as the 4th gens were not synthetic.

Topped it off, took just shy of a half a quart before she started dribbling. Reinserted fill plug, and hopefully thats the last of it until at least 30k. (I like to do maintenance a bit earlier than necessary, for peace of mind.)

Thank you all to those that alerted me about this. While it may not have made any difference, it certainly could have! Better to be safe than sorry.

Does the Mopar fluid contain limited slip additive?

 

[bpwj76]

Curious if this is the noise the OP heard with his truck.

https://photos.google.com/search/_tv_Videos/photo/AF1QipOP6ObR94HbC4qZUqmXmS6jsmjzg1oJFk380MUy

 

[Whoa_Ram]

Does the Mopar fluid contain limited slip additive?

No, you have to buy it separate. That's how it was on my jeep as well.

 

[Thekidcasual]

Anyone done this in Southern California. I’d pay for this to be checked and done I have no clue how to check this. Maybe a video on YouTube?

 

[KRField]

Anyone done this in Southern California. I’d pay for this to be checked and done I have no clue how to check this. Maybe a video on YouTube?

It’s actually very simple if you can use a ratchet wrench.

You need a 8mm Hex Socket (https://shop.advanceautoparts.com/p...RWqrn2bVjW0NXkc9iZQaAsZNEALw_wcB&gclsrc=aw.ds). Or if wanted but harder to use, a wregular Allen key.

Under the truck on the passenger side towards the top of the differential you will find the fill plug. Remove the fill plug and there should be a slow trickle of fluid come out. If not put fluid in till it starts to trickle out and reinstall the plug.

If you have the limited slip rear and have chatter (sounds like grinding) when turning, especially sharp turns. Go to the dealer and get a bottle of friction modifier to put in there.


Sent from my iPhone using Tapatalk

 

[RC Turner]

In the old days (and I expect yet today) fluid was properly filled when you could put your little finger in the hole, bend the finger down and you could touch the fluid. Filling all the way to the base of the fill file could cause the fluid to be over full when hot. Can contribute to leaks.