Differential covers...sealant or gasket?
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Tuned
Joined: Dec 2018
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Differential covers...sealant or gasket?
Most manuals and YouTube videos say to use RTV silicone for sealing the differential covers, but has anyone tried using/making gaskets instead?
Is there an advantage to using sealant over a gasket or the other way around?
I used sealant when I did my rear diff a few years ago...but I always have a problem lining up the holes, while lying on my back and supporting the cover....a gasket would be so much nicer.
Is there an advantage to using sealant over a gasket or the other way around?
I used sealant when I did my rear diff a few years ago...but I always have a problem lining up the holes, while lying on my back and supporting the cover....a gasket would be so much nicer.
More Turbo
Joined: Jun 2024
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From: Southeastern US
I really like the lube locker. Here's a thread that goes into all kinds of things, but it seems the lube locker is best called for if you don't have a drain plug on the diff cover. If you have a drain plug, then it doesn't really seem to matter one way or the other:
https://www.ford-trucks.com/forums/1...-sterling.html
https://www.ford-trucks.com/forums/1...-sterling.html
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Tuned
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Tuned
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So I got this done yesterday...fluid was BLACK...like coal.
According to my records, the last time I did this was just over 40,000 miles ago...yet the manual recommends it to be done every 105,000 and there is no mention of shorter intervals for towing.
I can't imagine what condition this stuff would have been in had I waited another 65,000 miles.
I used the Permatex stuff as show above, but if I were to manufacture my own gasket for this...should I use paper, fiber or cork?
According to my records, the last time I did this was just over 40,000 miles ago...yet the manual recommends it to be done every 105,000 and there is no mention of shorter intervals for towing.
I can't imagine what condition this stuff would have been in had I waited another 65,000 miles.
I used the Permatex stuff as show above, but if I were to manufacture my own gasket for this...should I use paper, fiber or cork?
More Turbo
Joined: Jun 2024
Posts: 631
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From: Southeastern US
I would stick with the Permatex, or go with LubeLocker.
Paper, fiber, or cork will weep and you will lose fluid over time.
How much fluid, and does it matter? I have no idea, but, with the Permatex or LubeLocker, If I see ANY seepage I know I need to stop and examine the fluid level ASAP.
If you don't mind checking your fluid levels every so often, then I would go with whatever is easiest for you to get.
I've seen people on YT make gaskets from Coke/Pepsi carton "cardboard" and it works (albeit with the seepage I mentioned above).
By the way, his video's are excellent IMO.
In my younger days, I made gaskets from "Mr. Gasket" cork for valve covers, diff covers, etc. They ALL weeped. Didn't matter what I did, they always seeped fluids. So when I got older and had some more cash on hand, I went with better gaskets. Less work and I like less repeat work for the same job.
Paper, fiber, or cork will weep and you will lose fluid over time.
How much fluid, and does it matter? I have no idea, but, with the Permatex or LubeLocker, If I see ANY seepage I know I need to stop and examine the fluid level ASAP.
If you don't mind checking your fluid levels every so often, then I would go with whatever is easiest for you to get.
I've seen people on YT make gaskets from Coke/Pepsi carton "cardboard" and it works (albeit with the seepage I mentioned above).
By the way, his video's are excellent IMO.
In my younger days, I made gaskets from "Mr. Gasket" cork for valve covers, diff covers, etc. They ALL weeped. Didn't matter what I did, they always seeped fluids. So when I got older and had some more cash on hand, I went with better gaskets. Less work and I like less repeat work for the same job.
Last edited by 2015 F-350; Apr 9, 2026 at 06:51 AM.
More Turbo
Joined: Aug 2025
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Glove up, and smear permatex on a paper gasket. Has never failed me.
Reusable rubber gaskets are great when they work. But theyre easier, not better.
Captured o-ring would be best. But ive never seen one on a diff cover.
Reusable rubber gaskets are great when they work. But theyre easier, not better.
Captured o-ring would be best. But ive never seen one on a diff cover.
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