2nd Gen Non-Engine/Transmission Vacuum or drain diff fluid

[BLandau]

I need to change the fluid in my front and rear differentials, but I will not have time to crack the covers. In most cases I take the truck to have the oil changed in town (I supply the oil and filter). When they performed a differential fluid change on my old truck, they sucked the old out with a pneumatically operated vacuum pump.



Would it be bad to have them perform this procedure when changing the fluids on the diesel?



Brent

 

[DavidC]

IMO all the dead material is laying at the bottom which I do not think your going to get out with a vacuum. What is the sense of changing fluid if the dead crap winds up floating thru the system. When you pull the cover you can make a quick inspection of a lot of components.



Dave

 

[Bucky205]

Wait till you have time to do it and open the differentials... Many avoid opening them because they are afrad of leaks. The reccomended way is to open the differentials. All the sludge settles in the bottom of the differential. transmission does the same thing on an auto. I am sure you have seen the magnet in the transmission pan. Metal on metal meshing over thousands of miles suspends particles and sludge in your rear end, that is why you service it. Break the seal on the housing, wipe interior housing with clean lint free cloth, inspect, clean the joining surface, use mopar sealant when reassembling, torque, fill until fluid comes out the check hole. Do no forget to add the friction modifier if your rear end calls for it (Limited Slip). $10 and 30 minutes difference in materials and time and much better for your truck.



Chuck

 

[ralphr]

I agree 100%, open them up and drain them, get all of the crud out of there! In fact with the cover off jack up each wheel and let it drain from the tubes, take a cloth and swab out the differential cover. Once done if you have a Mag Hy-tech cover to put back on, the next change should be like draining engine oil! (I would remove cover after that one again and go through all the swabbing etc. . to keep it clean) IMHO:--)

 

[illflem]

fill until fluid comes out the check hole

NO!

Follow the directions in your manual, 3/4'' below the fill hole in the rear and 1/2'' below in the front. Overfilling causes fluid to leak out the seals on the axle ends.

Been there, done that several times before reading the manual, what had always worked on other rigs in the past doesn't always work on these differentials.

 

[Bucky205]

What manual are you using? The shop manual may be different. I use "Haynes Repair Manual, Dodge Pick-ups 1994 thru 2001", ISBN 1 56392 429 3 and it says on page 1-29:



Quote: "Use a hand pump, syringe or funnel to fill the differential housing with the specified lubricant until it is level with the bottom of the plug hole. "



I figure if I place the truck on level ground, fill until it comes out the plug, wait a few minutes, fluid should drain until level with the plug. I am curious as to the difference in fill procedures in different manuals.



Chuck

 

[illflem]

It's in the owner's manual that comes with your truck and also the factory service manual.



I didn't think it mattered since I'd always filled to the bottom of the hole for years. After a few leaking differentials that stopped leaking once the level was to the recommended level or fluid was removed was convinced.

 

[rfcom]

You could also just measure how much you put in. My 02 service manual says the D80 /w 4x4 and LSD takes 4. 5L (9. 5 pints) of gear oil and 0. 3L (10 oz. ) of friction modifier. With no LSD, it's 4. 8L (10. 1 pts. ).



Jim

 

[stownsend]

Since I have never done this job before, is there a "graceful" way to keep from making a huge frickin mess when the cover is crakced???? I would probably do it if I didn't expect several quarts of gear lube all over my garage.



Steve

 

[rfcom]

I just put a catch pan under the diff before loosening all the bolts. Leave one of the top ones in, but loose when you crack the cover open. The oil will come out at a controlled rate and when empty, remove the last bolt and clean up. Oh yeah, the pan should hold a couple gallons.



Jim

 

[Bucky205]

How much of the friciton modifier are you guys with Royal Purple running. The dealer has a chart for a 2001 that reccomends 8oz with Dana 70 and regular 75w-90 gear oil. Does it change with the Royal Purple?

 

[illflem]

The amount of modifier seems to depend on clutch wear, there is really no set amount with any type of oil. Best thing is to start out with none then add 2oz at a time until the chatter stops, if you have to add any.

With Royal Purple some people get by with none, others need 8 ozs.

 

[DavidC]

I just did the Royal Purple 2 weeks ago. No additive needed for me.



Dave

 

[BLandau]

Hey everyone! Thanks for the tips. I think that I will finally have time to change the diff lube this weekend. I just bought some Schaeffer oil when I was in St. Louis a couple of weeks ago. I can't wait to crack the covers and see what is inside!