2nd Gen Non-Engine/Transmission Front Diff

[MRiley]

While out hunting I smacked the front diff pretty good. Got a good leak now and it looks like I'm going to have to replace the pan. My questions are:

1 What is the proper weight / specs for the fluid

2 Is there an anti sud agent that is suppose to go in there as well

3 Is there a gasket on the pan. Mine looks like it's just RTV.

4 How much fluid should it take. I've read that if you go above 1/2 inch bleow fill bolt it can leak out the tubes. .

Thanks in advance for all of you help.

MIKE

 

[BDaugherty]

Take all the cover bolts loose except for one. Leave that one 1/2 way. Use a rubber mallet or dead blow hammer to hit the cover sideways a couple times to break the seal of the silicone. When the oil has drained, remove the cover and wipe all the remaining oil out. Brake cleaner/solvent is an option, but I don't use it inside the diff. Buff/clean/scrape the sealer off the housing and cover. Clean it with solvent. Apply RTV silicone to both the housing and the cover. I like to put the cover in place and then just barely tighten all the bolts. After the sealer has had 1/2 hour to an hour to set up, I go back and snug up all the bolts. Refill with GL5 80W-90. With the truck on level ground, I just "fill-to-overflow". If you don't have any leaking axle seals when you begin, it shouldn't matter where the oil level is as far as leaks go. The book says either 3/8" or 5/8" below the fill hole, but it won't hurt it to fill it to the bottom of the fill plug.

 

[LandShark]

I would suggest that you get a owner's manual and factory service manual for your truck and service it as Dodge specifies.

 

[CumminsPower98]

I personally fill to somewhere between 1/4-1/2" below the fill hole as recommended. If I fill all the way up it sometimes pukes oil out the vent hose up on the passenger fender on longer drives. I have seen one other truck do this as well so there is a reason for the specified fill level. It may not happen to everyone and may depend on the oil used but I have seen it twice using Amsoil 75w90.

 

[MRiley]

If I fill all the way up it sometimes pukes oil out the vent hose up on the passenger fender on longer drives.

My truck does this all the time on longer drives. That is why I was asking about andi-sud. I thought I read somewhere that the factory specs call for some sort of additive. Anybody recall this?

 

[SRath]

I am a strong advocate for using a gasket instead of silicone. Preferably one the outstanding LubeLocker reusable gaskets for the Dana 60.



I had a REAL expensive lesson when I filled my Chevy K30 dana 60 axle with Mobil 1 synthetic and used silicone sealant on the cover. I bought my Dodge soon after, and the Chevy sat for several years seeing little or no use.



Then one snowy day, my wife's S10 Blazer was down for some forgotten reason and she drove the Big Blue K30 to work. The snow continued and she locked in the hubs and put the NP205 in 4Hi to drive home (less than 2 miles).



"Boy that truck sure makes terrible noises when it's in 4 wheel drive!" she said when she came through the door...



I went outside, slid underneath, and immediately found the pinion yoke would move in directions it wasn't supposed to... I dropped the cover off the front diff with an oil pan underneath. A handful of rollers from the destroyed bearings were all that came out. Not one drop of oil.



The cover and the housing both had perfect silicone beads; from the oil line on UP.



Not the tiniest evidence of silicone remained below the oil line. During all the time it sat, the Mobil 1 had literally dissolved the silicone and slowly leaked out. Slowly enough not to leave a telltale puddle in the gravel/grass where it was parked.



I have had seal leakage problems with Mobil 1 oils on many different vehicles. So no more Mobil 1. Only Amsoil for everything I own! No more silicone, either!



I had to use silicone on my Dana 80 cover 2 years ago because no one local had a gasket. I see it is seeping a little now, too, and will be addressing that this week, with a gasket!

 

[CumminsPower98]

Interesting. I am the exact opposite. When I used gaskets in the past it seemed like they always seeped a little even with a sealer on there. Since going to silicone I have not had one problem in many years on any rigs. I have worked on plenty too since I twist wrenches for a living. Maybe the silicone you used wasn't made for the application. Now if I had a good rubber covered steel gasket like some newer rigs come with, I would be all for that over silicone any day.

I'm not aware of any anti-foaming agent recommendations and so far haven't read about that on here.

 

[MRiley]

I'm not aware of any anti-foaming agent recommendations and so far haven't read about that on here.

Thanks for the feedback

 

[SRath]

That LubeLocker gasket I prefer is a steel-cored, double molded silicone ringed gasket like you described, Mark. They keep saying a Dana 80 gasket and GM Corp 14 bolt will bne available "soon", but it has been a couple years now and I still haven't seen any.

The silicone that failed me in combination with the Mobil 1 is the orange colored "copper" stuff. I had an unopened tube of it and used it up. These days, if I must use silicone on anything, I only use Ultra-Black.

Scott

 

[Extreme1]

Then there's always the Mag-Hytec o-ring cover option...

 

[CumminsPower98]

Yeah I would like to have one of those but hasn't been a priority for me yet. I should have had one when I was towing for a living. Now the truck sits most of the time.

 

[Missouri Mule]

MRiley, a very small amount of "Friction Modifier" is used in the Limited slip axles.

 

[Dave M]

I used the Lublocker gasket mentioned (about 1 month ago when repalcing front axle seals) and it worked great... no leaks. The gasket cost about $18 and with shipping about $28... . kinda high for a gasket but no silicone needed and no waiting for sealant to dry.



The lubelocker is a thick steel-backed gasket with (it looks like) beads of dry silicone about it. Just torque it down and your done... no waiting for silicone to dry.



I refilled with 85-90w RedLine synthetic from NAPA.

 

[MRiley]

Thanks for all the replys. I used the Balck RTV and let it set up about 40 min then re toruqed the bolts. No leaks. I used Synthetic 75 -140. Was that just over kill? I had the guy and Napa look it up and that is what their book was calling for so I went with it. Just seems to be over the top for the front.