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Old Nov 27, 2012 | 10:03 PM
  #1  
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Rear Diff Oil Change

Im going to change the rear diff in my 2000 psd. Ive done it once and need a refresher. Don't want to screw anything up.

Any good write ups ?

I guess i really need to know.....

a. What type of RTV should i use, and do i put it on then install the cover torque bolts/nuts and fill with fluid. Or do i need to let the rtv set up for a bit before i install cover , tighten bolts/nuts and fill

b. What type of oil and how much? " I read about having to add a slip additive to some and none to others. Id rather not have to add any. Is there a type that i can just pour in and go. And how much do i throw in? is there a check bolt or plug"

Sorry for all the questions. Im laid up with the FLU bug and bord out of my mind getting a list together for when i get up and about.
 
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Old Nov 28, 2012 | 06:30 AM
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Welcome to guzzle's Rear Differential Maintenance Web Page

Here you go.
 
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Old Nov 28, 2012 | 07:10 AM
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Guzzle's writeup pretty much covers it. Be sure that you clean off ALL the old rtv off the diff. Let the RTV skin up for at least 20 minutes or so. I waited around an hour or two after bolting on the cover before I added fluid and added to the fill plug level. 70w-140 Synthetic diff fluid only.
 
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Old Nov 28, 2012 | 07:52 AM
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And, another chance to add to your christmas list. The later model rear diff cover, finned aluminum, available from Tousley Ford for around 45-50 bucks. Looks great, seals nice being stiff aluminum. You will need longer bolts, I found some ss allen head at Fastenal.
On your additive, I had chatter issues last year with only one ford bottle, two worked
great this year. IMHO you need it. Ford agrees, that is with the synthetic 75-140.
 
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Old Nov 28, 2012 | 08:52 AM
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LOL Awesome guys thanks. And Tom....... your on it tonight !
 
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Old Nov 28, 2012 | 08:54 AM
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As I finish my second cup of coffee, my brain remembered something. Last year, I did NOT use any additive when I changed fluid. That is why I had chatter, towing a 5th wheel by the way. I added one bottle while sitting in an Oregon campground. Not the way to do it. That helped some, but still had some chatter.
This year, when I did the cover, I added two bottles of additive, and had no chatter on our summer trip.
 
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Old Nov 28, 2012 | 10:13 AM
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I'm doing this this weekend as well. For what it's worth, I went to my local dealer to get some of the additive and their grizzly "been there, done that" 7.3 expert was really insistent on 3 bottles, so that's what I grabbed. So, Tom's recommendation to do two is definitely good advice. I was planning to just do the 3 bottles of course. Just passing along another opinion.

While it's out there, is anyone aware of any possible harm to the LS mechanisms using three bottles. Seems silly, but thought I'd ask just in case.

Thanks for the lead on the finned cover, going to look into that for sure.
 
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Old Nov 28, 2012 | 10:25 AM
  #8  
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Originally Posted by howellt39
I'm doing this this weekend as well. For what it's worth, I went to my local dealer to get some of the additive and their grizzly "been there, done that" 7.3 expert was really insistent on 3 bottles, so that's what I grabbed. So, Tom's recommendation to do two is definitely good advice. I was planning to just do the 3 bottles of course. Just passing along another opinion.

While it's out there, is anyone aware of any possible harm to the LS mechanisms using three bottles. Seems silly, but thought I'd ask just in case.

Thanks for the lead on the finned cover, going to look into that for sure.
Oh the part number on the cover 8C3Z4033A, I got mine for 50 bucks or so they wanted 80 for the bolts.

12 5/16 - 18 x 1.25" bolts have worked just fine over the past year and half. And I think it set me back about 15 bucks at a local hardware store.

With respect to the additive, I would add one bottle and see how it goes and if needed add the second. I have red line 75w140 in my rear diff that came with the LS additive already suspended in it so I didn't need to use any.
 
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Old Nov 28, 2012 | 01:04 PM
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I forgot what i used last time, or how much fluid. I know for a fact i didn't add any ls additive. I do notice "more when towing" that when i am stopped about to take a left or right turn upon acceleration making the turn from a stop i feel a grinding in the rear end. Probably due to not enough or no additive.

So if i get synthetic oil with the additive in it is this sufficient enough or should i add some additive along with it.

Also how many QTS of fluid do i need ?
 
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Old Nov 28, 2012 | 01:15 PM
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Four quarts of 75W-140 Mobil 1, and NO additive, should get you back on the road. It may chatter slightly in sharper turns for a short while (maybe a day or so), then it stops.

Too much additive (THREE?!?!) will tend to disable the clutches to the point that you may not get any limited-slip action at all. Same as an open-differential, and who wants that?

Pop
 
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Old Nov 28, 2012 | 01:25 PM
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Thanks Marv
 
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