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Discussion Starter · #1 ·
Okay. After a succesful Read Differential Gear Oil change (thanks to all for the tips and help) I'm going to try another challenge.

Tranny and Front Differential Gear Oil change.
I have over 85K on this manual transmission and over 130K on the front defferential gear oil. No problems so far but I think it's way over passed due.

So things all of you guys are experts and nice at this, I would like to hear your input.

This is what I found regarding Tcase/Tranny (Are these the same thing or do I need to worry about 2 drain plugs?)

This is from 4x4wire.
http://www.4x4wire.com/forums/showflat. ... =1&fpart=1

Gen2 maint... 4L30E
The main topic here... 4L30-E. Yes, the service manual does not REQUIRE the DexronIII to be changed.
However under te following extreme conditions, it SHOULD be:
Towing
Short Trips
Dusty Roads
Rough Roads

Hmm... I meet 3 of the 4 and @ 85k, so its time to change the filter, I have been doings flushes once a year.

So we get down there, look at it and determine what to do.
* Support drivetrain on the t-case skid plate with jack.
* Unbolt twisted, bent t-case/tranny crossmember.
* Remove brake/fuel line heat shield protecting said lines from the crossmember.
* Unbolt tranny support from crossmember and move crossmember out of the way.
* Remove tranny support from the tranny.
* Drain flid from tranny pan (2 plugs, one low, one high[allen head]).
* Once fluid has drained, unbolt the pan from the tranny and set aside.
* Unbolt filter from the tranny and discard.
* Remove gasket material left on the tranny and pan.
* Clean gasket mounting etc with a solvent on tranny and pan.
* Remove magnet from bottom of pan and clean all metal dust remnants from magnet, and wipe out pan after all fluid has been drained.

[rant on]Since some BRAINIAC at GM/Isuzu designed the 4L30E WITHOUT a dipstick or any other way to fill the fluid, you get to take a bath in Mercron, no two ways around it... :mad: Remember the allen head plug I referenced, well that is the overflow aka FILL plug too!!! So, since the overflow hole parallel to the ground, how do you suppose you place fluid vertically into a pan that holds the fluid, maybe 3" below that hole? WTF, some people shouldnt live, or breed as the case might be.[/rant]

* Install new filter on the tranny, round hole down.
* Fill up the pan with 6-7 pints of fluid (nearly to the overflow line.
* With two people, lift up full pan to the tranny, and stick 2 bolts in opposing corner with each person (all 4 corners are bolted)
* Complete the installation of the tranny pan, and reverse process for the crossmember, support, and jack.


NOW, what about the front differential. This is ANOTHER drain plug, correct?

Few questions:
What's the recommended Tranny Oil, weight, etc?
How much Oil should I buy?
Is this a 1 man job or should I ask for help?
Do I need a gasget for the Tranny Pan?
Transfer Case and Tranny? Are the same thing?

BTW, If you find some of this questions stupid, forgive me. I'm just a guy getting into 4wheeler and learning as I go.

Thanks in advance
 

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The tranny is slang for transmission. T-case is short for Transfer case. These two things are separate and have separate drain bolts and fill bolts, they are however bolted together. The t-case is what sends power to the front wheels via the front driveshaft. The transmission is what sends power to the transfer case and depending upon what you have selected the 2wd/4wd/4wd low then your transfer case will determine where the power gets sent from there. Just the back wheels, back and front in high gear 4hi, or back and front in low gear 4wd low. The low and high gears are inside the transfer case. I'm asumming you know where your front diff is and what it looks like.

As for the fluids that go in each, the transmission takes Automatic transmission fluid, and the front diff takes gear oil (same stuff you put in the rear diff), although you don't need to worry with the limited slip additive like you did for the rear.

The transfer case takes 10W-30 oil. It has a drain plug on the bottom and a fill plug on the side. Drain it and fill it until it just comes out of the fill hole. I'm thinking the bolts are either 22mm or 24mm. 2 quarts will do this no problem. I think it only takes like 1.5 quarts.

You will need to purchase a fluid pump, you will have to pump the fluid into the tranny and the t-case. Both are kind of messy with the tranny being the wierd one. The fill hole is on the bottom. So you are filling it straight up. The truck has to be running and up to the correct tempature to fill the tranny correctly.

Yes you need a new gasket and filter. I usually change them anytime I pull the transmission pan. You will have to take out the rear crossmember to get to the back bolts in the transmission pan. Support the trans with a jack or a jack stand.

All of these can be done by one person but it's better to have a helper to hold the fluids as you pump them or vice versa. You'll need about three hands to do all of it.
 

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Discussion Starter · #3 ·
Bigpoppax2 to the rescue. Thanks man.

I have a manual transmission, is this the same as automatic transmission. I've seen the automatic transmission fluid at the car store but did not see anything for manual?

Once I remove the pan of the tranny, how to I flush the rest of the oil? Do I use the drain plug?
 

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No there is no filter on a manual, it will be much easier to do than an automatic. There should just be a drain plug and a fill plug. No pan, no filter no having to have the truck running. Just a dump and fill just like the rear diff. only with a drain plug. If it's the same as the older ones it also takes 10W-30 engine oil.
 

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hi,
you can drain the manual trans fluid and take out the fill plug. Then take the shifter out and fill from the top, until the oil comes out the fill plug. This is how i did it on my 95.5 2wd Rodeo. Yes, it seems like a pain to remove the interior parts to get to the shifter, but its alot less messy and easier to fill. Some Isuzu manual trans take ATF (automatic trans fluid) like the 2.6L manual Borg Warner 5 speed. but im not sure about the v6 version. I have yet to change that fluid at 112k on my 96 4x4. Read the owners manual for the proper trans oil. good luck
ron
 

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Yea, check the book. I'm 99.9% sure that it takes motor oil. I used the same pump that I used to fill the diffs on my 5-speed. Any motor oil left in it wouldn't dillute the gear lube enough to worry about.

One suggestion: Remove the fill plug first! That way if you can't, you won't have drained the tranny with no way to refill it. Also, be sure to remove the plugs with the transmission COLD. When hot it is very easy to strip the threads out of the fill plug hole. Ask me how I know this :)

BTW, for anyone reading this, the TOD transfer case takes ATF, just like the transmission.

-Tad
 

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if the fill plug is stuck, you can always see what the trans capacity is and fill thru the shifter hole ;) or get the fill plug wtha box wrench and tap gently on the end far from the plug. The vibration will usually loosen up any plug without damage to the threads. TAP GENTLY though.
 

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Discussion Starter · #8 ·
Excellent, thank you all. I'll do this this weekend. Since all I need is 10W-30 for the Manual Transmition and Transfer Case. Should I use Synthetic?

I'm doing Front Differential change as well. I'll be using the same as Rear Diff.

i'll let you know how it goes, thanks in advance.
 

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Discussion Starter · #9 ·
Thanks for all the information everyone.
I finally got around to do it. Those bolts were soooooo hard to remove. One thing I noticed was that when I removed the FILL plug for both Tranny and T-case A LOT of oil came out thru these holes

Were they over filled? if so, how?

I refilled it as instructed and it feels better, not too much of a difference but I just wanted to do since it had been so long. The old oil stunk so bad.

Thanks again.
How much did I save? How much does this normally run at the dealer?
 
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