Rear axle maintenance

[btoscano]

Hello,



I have a 1990 Dodge 3/4 ton with 3. 07's. Last night I changed the differential fluid. This was my first experience doing so, so I have some "newbie" questions (even after searching the forums).



It was very difficult to get the rear cover off. I read about comments for "prying with a screwdriver", etc. I used a pry bar, hammer, and screwdriver and wacked and wacked and wacked before it even started dripping. Finally, the back cover came off! There was gobs of gray RTV everywhere. An bead inside of the bolt holes in the cover, oozing from the outside of the cover, on the ends of the bolts, etc.



I purhcased the RTV from the Dodge dealer for the job (the red stuff) and applied it lightly around the inside edge of the cover (inside the bolt holes) and U's around the bolt holes with the open part of the U sharing the RTV of the inner bead. Now its wet on the bottom (where I let the gear lube drip down for a while). The bead was about 1/16" wide.



So, my tought it that I should have used brake or carb cleaner on the surface of the differential (I did use brake cleaner on the cover).



The fluid that came out was basically "black" in color but there were no solid chunks of anything and the gears looked fine. There was a very thin coat of buildup on the non gear surfaces, which I wiped away with a lint free rag.



Questions:



1. Did I put the bead of RTV in the right places? how wide should the bead be to prevent leaks, yet make it relatively easy to service in the future?



2. How high level should the gear oil be? My owners manual makes no mention and I filled it until it would start coming out of the fill plug. (I've read others in later gen forums say 3/4" below fill hole, etc) ???



3. What model Dana axle is this? Can I purchase a gasket for it at "McParts" ?



4. I won't ask which gear oil to use



Thanks,

Brian

 

[Philip]

Being it has 3:07's it is a Dana model 70.



The red RTV is most for high temp uses. I do not know why someone gave you that. I do not use RTV for gaskets most of the time. Any good parts store can get you a gasket for that cover. I usually keep one hanging on the wall of my garage.

 

[btoscano]

Philip,



Maybe I should have called the color "ruddy brown". Its Mopar RTV for axles, so I'm *pretty* sure its the right stuff. I check with the auto parts stores, as a gasket seems like a better idea anyway.



But what about the fluid level?



Thanks,

Brian

 

[paccool]

I fill mine to the bottom of the hole. There was a discussion on this a few months back, do a search and you should be able to find it.

 

[btoscano]

paccool,



I have found information in the 3rd gen forum, but I'm not sure that applies to the axle in my truck. That's why I was asking.



Thanks,

Brian

 

[cerberusiam]

You can use RTV or a gasket depending on preference, either will work fine. I usyally use RTV black but the red will work, just higher temp. If you use the RTV you need to take care to clean all the surfaces well, diff and cover. The RTV will weep if there is an oil film under it. Also, you need to check the bolt holes in the cover and make sure they have not pulled in from tightening. Tapping each hole from the inside with a ballpeen hammer will insure the most surface contact on the cover. While your at it make sure there are no nicks or dings that cold hold the cover away from the diff. I put a bead about 1/8 wide and 1/8 deep around the diff and outside the bolt holes then let it set up for 15 to 30 minutes depending on temp. If the cover is square and straight, the diff surface free of oil and you let the RTV set up a bit you should have as good a seal as a gasket. Clean off the bottom of the diff real well and run for a while to see if you have a leak or just residual from the draining.



Yes, if the cover has not been off for a while it will take some work to get it loose. Good luck.

 

[RGT]

I think the fill level should be to the bottom of the plug hole. I think the owners manaual says 1/2 inch below that, but I have seean other manuals that say that the level when checked can be up to 1/2" below the plug hole and am assuming the Ram owners manual should read the same, someone please tell me if I am wrong.....

 

[Greenleaf]

My owner manual tells me 1/2" below from what I remember. Not looking at it right now though. I know it's 1/2 or 3/4", something like that. I changed mine this past summer. Used a gasket and a bit-o-cement to hold in place while installed it. Zero-leaks



Greenleaf

 

[btoscano]

I checked the owners manual once again and finally found a reference: "The fluid level should be level with the bottom of the filler plug opening. "



Some have told me I should stick my finger in and fluid should be up to the first knuckle. On this forum I've seen references to 1/2" or 3/4" which I think is roughly equivalent.



The good news is that the leak hasn't gotten worse yet. Just a bit "wet" on the bottom of housing so I'll leave it for now. Pep Boys and Advance Auto and O'Reilly's didn't have the Dana 60 or 70 gasket in stock. I'll try to get one, or make one of my own.



Thanks,

Brian