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LMM Front Diff leaking, Seal Kit?

20K views 25 replies 11 participants last post by  Draz 
#1 ·
need to reseal my entire front diff, is there anything special I should know about removing it or is there any special seal kit/gaskets I will need beforehand, or is it all just siliconed together. Any help would be great thanks.
 
#3 ·
Anyone with any experience pulling one of these apart? Would like to hear something better than a should be, anyone? Definitely leaking at pumpkin half and then some, long story...
 
#5 ·
Its leaking at two pumkin halves, right down the center and also at the shaft where the electronics hook into the pumpkin
 
#6 ·
Good luck. My 08 lmm would leak every time it got cold. Took it to the dealer 5-6 times and it wasn't until 2011 when I blew the dif and the dealer replaced it did it quit leaking.
 
#7 ·
Sub'd for any info. Mines doing the same.
 
#8 ·
Why i want to take care of it right the first time, wierd that it would leak when it got cold though, mines the other way around. The oil gets thinner in the summer and leaks out quicker than in the winter when its thicker.
 
#9 ·
First time hearing about it leaking randomly though, long story short, drove very far distance in 4wd, oops, blew oil out the breather tube and cooked all seals, hence now leaking in a few spots so i need a complete resealing. Still hope someone has had one of these diffs apart here?
 
#10 · (Edited)
need to reseal my entire front diff, is there anything special I should know about removing it or is there any special seal kit/gaskets I will need beforehand, or is it all just siliconed together. Any help would be great thanks.

Yes, they are just siliconed together and the key to having it be successful is twofold. First make sure the surfaces are completely free of any oil or other debris (brake cleaner, then dry well). Second make sure the breather tube has no obstructions and flows freely. I would also suggest replacing the axle seals while you're in there since they will be easy to access at that point. I would use an aerosol silicone sealer called 'the right stuff' (Permatex Ultra Black and Ultra Gray are also good alternatives) as it does a great job sealing. Keep in mind a little goes a long way and to always make sure the silicone gets applied towards the inside of the bolt holes.
 
#11 ·
Sounds like what ive been waiting to hear, anything tricky or surprising i should be ready for or is it all a pretty straightforward removal and disassembly etc... ive read the axle shaft removal can be quite a hassle...
 
#12 ·
Yes, the C-clips on the axle shafts can be a pain but they should be alot easier if you already have the case split since you can push them out from the back side. Try not to use too much force or you may damage the carrier bearings. If those get damaged you'll be doing a rebuild on it after that.
 
#13 ·
i noticed mine had some oil on it but i think its coming from the driver side axle seal maybe?? when u guys say that yours leaks when its cold out, where is it leaking from?
 
#14 ·
The driver's side is the weak point on these differentials. Go under the diff and push up on the CV where in enters and see if it moves up and down. If it moves any significant amount then you're likely looking at a full rebuild (ie just replacing the axle seal won't stop it from leaking).
 
#16 ·
ok now i dont feel so bad lol :drink
 
#19 ·
add me to the "front diff leaking" club. gm should have a recall on them and pump rub!!! come on gm use your money to take care of your customers.
 
#21 ·
probably had to do with the dpf being removed :rof
 
#23 ·
driving a long ways in 4wd shouldnt cause a problem, unless you were low with oil, then it might kill the bearings/gears but it shouldnt get hot enough to do damage. I suspect you just have a leaky diff and it was nothing to do with the "event". They pretty much all will leak at some point in their life, whether its from the axle seals, the pinion or the case halves. The biggest thing is to check the fluid level once you notice a leak to make sure you dont do serious damage.
 
#24 ·
ya it was definitely from driving in 4hi through the desert at 115 degrees towing a boat for 4+ hours, blew out half the oil all over the wheel well, side of truck and boat. never a drip before but now it drip drips onto the driveway, just got to hot and melted the silicone down. thankfully im not getting any other noises from the diff but hopefully it will stay that way. but never had a single drip before this so interesting to hear so many people say theirs is dripping. but needs to be done, multiple drips going on.
 
#25 ·
I guess I just find that hard to believe but regardless of the actual cause, leaks arent uncommon with these, most dont leave puddles but you see them wet around the shafts and seals. With yours its possible that the vent was plugged and the heat let enough pressure build up to push the seals out, I have seen that scenario.
 
#26 ·
i guess it is possible but it did also blow about half the fluid out the vent. so if it was plugged then it certainly became unplugged when this happened. I just think that if this fluid got hot enough to boil and blow out then the silicone probably cant stand that kind of heat and has to melt away a little. it was just that hot for that long, never realized it blew out or anything until i got home. its not a puddle but a new spot on driveway every night after sitting. just need to get it done. thanks
 
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