89 4runner/22re/5speed

On the way back from camping this weekend (great time by the way) I noticed two things that have me a tad concerned.

1) The T-case shifter gets rather hot after a during a long trip, by long I mean 60 miles or so.

2) Above 70 mph on the way home I noticed a strange vibration/rumble/low decibel noise.

Those two things led me to stop the rig and do some looking. The U joints are all tight, no issues in the front/rear suspension that I could find. I did however lay my hand on the rear diff and it was so hot that I couldn't touch it for more than 2 or 3 seconds without some pain. Since I didn't really have any options I went ahead and drove it home (about another 15 miles) at lower speed and the vibration was not present.

I have dino juice in the rear diff due to the locker and am wondering if it can break down over time. No leaks that I can see other than the bottom of the diff being a little damp but no drips. Planning on a drain/flush/refill this weekend, is there anything that I should look for other than the usual (metal flakes in the fluid, water in there, etc)?? I'm guessing it's time for some severe gear type fluid although I'm unsure which to use. Oh and can one of you recommend a good fluid or something to use to flush the diffs/tranny/t-case?

Thank you for your time.

 

my tranny gets pretty hot to feel through the floor... im sure its pretty normal. I would drain/flush the rear end, and inspect the oil.

 

100 miles at 70 mph could cause 150deg F from a diff under normal driving conditions, have seen same miles on highway make a trans and tcase 180 deg F. i would look at fluid and make sure no water or metal and color are good, if those are ok I would not worry i tend to lean tward OE fluid but since you have a locker google the manufacter and see if they recomend something besides there own fluid.

As for vibration or rumble tire balance is cheap to check first.

 

My tranny/Tcase gets pretty hot too. I put Redline MT-90 in the tranny and Redline 75W-90 in the Tcase. It helped some, but it still gets pretty hot in the summer time.

I have never put my hand on the rear diff though, so no help there.

I would say it's normal.

 

Yeah, the rear diff can get toasty (as well as the t-case and trans). Pick a quality synthetic 75w-90 gear lube and change the fluid out if you're worried, though don't expect a big change in temp. Just from personal experience I'd be careful with MT90 in the transmission if you plan on towing or other continuous heavy load situations (or long distance in the desert, for example) - not saying it's bad juice, but it pours out more like engine oil than gear lube. If your shifter is notchy or you have other shifting issues, I might recommend 1 qt MT90 with a good synthetic for the remainder

 

I say the heat is pretty normal... especially when dino oil is used
just switch to synthetic using the toyota recommended viscosity and you're fine

synthetic will allow the geartrain to rain a little cooler and can handle high heat much better... it won't break down as easily from heat or shearing... that is very important to ensure proper lubrication

I use redline 75W90 in mine, and it doesn't get too hot... just about 120 degrees after a 20 mile drive

 

ou gotta remember the exhaust runs right by the tranny and t case so that heats it and the floor up a lot too. as long as your fluids are full youre good. mine strted smoking once when i first got it, like first time above 70. the diff was 2 quarts low... lol

 

i did royalpurple 2 QTS then 1 QTof valvoline synthetic in the trany made a huge difrence in shifting and smoothness gona do the same for the diffs to when thier up for a change ( i do every 10 for the rear and 20 for the front )

they sale after market dif covers with little fins in them and their suposed to be larger to more fluid more to get hot one of the people i work with got one for his dodge and says its has helped with the temp on it same principle should work but thier pricey though and unless your towing a horse trailer weekly like him i dont think you will realy need it

 

well there's no diff cover with the rear end because it's a 3rd member setup! domestic trucks aren't this way and that's why they can get aftermarket cooling covers...

I doubt you can do much to the IFS diff cover either as there's other things in the way

 

Thanks for the replies folks. I've got Royal Purple synthetic in the tranny and t-case already and can't run synthetic in the diffs since the lockers don't like it. I'll check all the fluids out this weekend (drain a little from each spot and check for metal or foreign bodies) and top them all off with the required juice. I just never realized the rear diff would get that hot.

 

check with the maker of your locker just to ensure it's a normal temp.

As far as rumble, do you have any play in your rear wheels (bearings)?

 

Hey Junker- The ring and pinion is about 97% efficient.....3% power lost to heat. If you were carrying a load in your truck that would cause more heat also. In addition, a 488 or 529 would be spinning faster and tend to create a bit more heat than a 410. You aught to see how hot our ring/pinions get here in Phoenix Supposed to be 113 tomorrow afternoon. yikes.

 

why do they "not like it"? who says so?
all the high quality synthetic gear oils I've seen are locker and limited slip compatible

in fact, the torsen LSD in my rear end works better with the redline than with the valvoline dino oil that was in there for the break in

 

New Mexico in the the summer.

Enough said!!

 

half the dam state is on fire, of course its hot lol

 

There's talk that the fires were started as a distraction or possibly to hurt the state financially. .......in other words, coyote drug runners or muslim terrorists.

 

idiots with suvs

 

idiots with foreign suvs?

 

actually the one near santa fe is said to have been started by an atv

 

No wheel bearing issues that I know of.

I'm running 4.56's so that may account for some of it and I did have about 500lbs of gear in the rig.

The lockers told me they don't like synthetic, more precisely they showed me they don't like it by refusing to unlock. (Aussie/Lockrite)