1st time changing differential fluid.. advice

[Wardog]

We're taking off Friday with our fifth wheel. Going to Boulder, CO, from San Diego. Thought I'd get a little ahead of the 15K maintenence schedule.



I'm going to change the rear axle fluid tomorrow and didn't find what I needed on a search. Never done this before, so I thought I'd listen to what you experienced guys have to say. I take it you have to take all the bolts off and remove the rear cover. Do you need to remove the access bolt first and let it drain some, or just take the cover off? I've got the 11. 5 limited slip. I read that the gasket is reuseable. So, after I let it drain out ( how long? ) I put the cover back on and fill with GL-5 75W-90 until it comes out the access hole? I plan on torquing the bolts to 30 pounds.

Can I buy the fluid at kragen, etc. ?

How hard is it to find the water pump weep hole?

Lotsa questions. . appreciate any help you might offer.



Anything else I should do/know?

 

[rbattelle]

The procedure I follow when I change differential fluid:



1. Crack open the drain/fill plug. This is done first because it can be a pain to loosen it while trying to hold the cover in your hands.



2. Remove the bolts around the housing. I usually start at the bottom and work my way up, so that the topmost bolt is the last to be removed. I've found this to be a relatively "clean" method.



3. If you've parked on a level surface, most of the fluid will come pouring out as the cover is removed. I would advise against parking with the nose pointing downhill; if you must park on a hill, better that the nose is pointing uphill to help with draining.



4. Some people will jack up each rear tire (one at a time) to get the fluid that's in the axle tubes to drain. I don't personally bother, but it's not a bad idea.



5. The o-ring is reuseable. Be careful not to bend or deform it [I did this the last time I serviced the differential and thought I was in big trouble... I got lucky]. I recommend coating it with a thin layer of fresh gear oil before reassembly.



6. Remove the drain/fill plug and clean it off (it's magnetic).



7. Place the cover back on the differential and torque it down. You can follow the recommended torque for the bolts (which I think is 30 ft. lb. ), but some have actually snapped bolt heads from this. Personally, I use my right-hand torque wrench set on "snug". Never had a leak.



8. Refill the differential with 4 quarts of your favorite fluid. I won't say anything about what brand or weight, but make sure it's fully synthetic. No limited slip additive required.



9. Replace the drain/fill plug (don't forget this step).



Done and done.



-Ryan

 

[Big_H316]

Same thing rbatelle said but I mixed mine 50/50 with Lucas Synthetic gear oil. Did mine for the first time at 100k and was still clean as the day it was put in. I'm right 200k now so i guess I'll change it again next week just to see what the Lucas mix has done. I'll keep you posted on the outcome but I'm quite sure it will be the same as before.

 

[klenger]

Note that 100% synthetic gear lube is required per the owner's manual. I use Mobil 1.

 

[JHardwick]

Ryan!!!!



You didn't spray the pumpkin out with a can of brake cleaner? :-laf



I did, but was probably not necessary. I also wiped the bottom out with a rag.



Based on what I saw, it'll be at least 50K miles before I do it again.

 

[Tony T.]

I have been debating on changing mine out at 30K which is in about 800 miles. I changed it at 15K and the gear oil looked like new (factory fill). Oo.



Tony

 

[bombero]

Oh well, I will get fried but when mine is due, I will probably: Take out the plug and see if there is a lot of grey stuff stuck to it. If not Ill suck out as much of the lub as I can using a small vac pump I have. Replace it with redline syn. about 3/4 in below the hole. I guess I am just lazy!!

 

[robert4570]

Oh well, I will get fried but when mine is due, I will probably: Take out the plug and see if there is a lot of grey stuff stuck to it. If not Ill suck out as much of the lub as I can using a small vac pump I have. Replace it with redline syn. about 3/4 in below the hole. I guess I am just lazy!!

You beat me to it .

I used to take the diff cover off but found it much easier to just drive a bit to get the diff hot , there by stiring up the fluid. Remove the fill plug and drop avac tube down to the bottom and suck out the old fluid.

No mess, sure a little is left behind but 99% of the old is removed.

 

[mberry]

We're taking off Friday with our fifth wheel. Going to Boulder, CO, from San Diego. Thought I'd get a little ahead of the 15K maintenence schedule.



I'm going to change the rear axle fluid tomorrow and didn't find what I needed on a search. Never done this before, so I thought I'd listen to what you experienced guys have to say. I take it you have to take all the bolts off and remove the rear cover. Do you need to remove the access bolt first and let it drain some, or just take the cover off? I've got the 11. 5 limited slip. I read that the gasket is reuseable. So, after I let it drain out ( how long? ) I put the cover back on and fill with GL-5 75W-90 until it comes out the access hole? I plan on torquing the bolts to 30 pounds.

Can I buy the fluid at kragen, etc. ?

How hard is it to find the water pump weep hole?

Lotsa questions. . appreciate any help you might offer.



Anything else I should do/know?

I changed mine early too. Ryan laid out all the steps needed. I used Royal Purple 80-140 in the rear and 75-90 in the front.

 

[Wardog]

Thanks for your help. Can you tell me what type of vacuum you use to remove the oil?

I'll tear into it tomorrow. I'll take the bolts out the first time, but the vacuum method sounds pretty good for future changes.

John

 

[MMeier]

Just pull the bolts and do it right!! Ain't no big deal.

 

[rbattelle]

You didn't spray the pumpkin out with a can of brake cleaner? :-laf

I did, but was probably not necessary. I also wiped the bottom out with a rag.

I never bother with the brake cleaner. Too afraid to leave residual cleaner floating in there. But I do wipe out the bottom with a rag... I just didn't mention that.



Sucking the fluid out the fill hole is convenient and easy, but pulling the cover allows you to inspect the differential for abnormal wear.



-Ryan

 

[DPKetchum]

Just remember thats of posts about using the FACTORY torque on the cover bolts of 30ft lbs and bolts SHEARING off. Probaby tighten by hand and use your best judgement.

 

[KENNETHMD]

Vac Pump

Getting ready to change my diff fluid, can any of you guy's point me in the right direction, As to where to buy the Pump I need to suck the fluid out I just don't know what kind i need, and how much it costs.

Thank's in advance

2005 laramie 3500 quad cab 48RE 4:10 limited slip Black with Mopar nerf bars, mud guards, weel liners chrome fuel door, and exhaust tip, Premium tonneau cover,

 

[LightmanE300]

I agree with everything in Ryan's posting aside from not mentioning to clean the inside of the diff cover. Each time after 15k, I've found the diff cover to have a nice coating of darker/dirty stuff. A little degreaser and some paper towels usually takes care of it nicely, and I like putting it back spotless. I also wipe out the inside/bottom of the diff as best I can to get as much old fluid out as possible, but I like Ryan have been a little paranoid about spraying carb cleaner or the like in there for fear it may stay in the diff. Now that I have the PML cover, I will simply pull the drain plug and drain the fluid, and refill. I think every other time I may take it off and clean the pumpkin though. Good luck wardog.

 

[Wardog]

Thanks to everyone for your help. Got the job done today. Piece of cake, really. I did notice some metallic particles, but probably normal.

I will probably be buying the Mag Hytec cover when I do this the next time. I'm not sure it makes a big performance difference (heat wise), but having the extra oil and ease of replacement and good looks can't be bad! Found a place I can get one (for the '04, 11. 5 model) for $251 shipped.



http://www.consperformancechips.com/catalog.htm



You guys are great! Thanks for helping us non-wrenchers!



John

 

[trucknut]

One important point to do before you pull the diff cover off.



Clean the dirt out between the diff cover and the carrier (on top). The dirt seems to build up on top of the gasket. As you remove the diff cover all the dirt falls on top of your nice clean gears. Its alot easier to clean the dirt off before the cover is pulled vs picking and flushing the contaminated gear assembly.