8.8" Leaking after new gasket install

[ratdude747]

I replaced my differential fluid and resealed the composite cover with a fel-pro paper gasket. But after a few days I noticed that I'm leaving little puddles from said differential.

I noticed that, like my former ranger's 7.5" rear end, this one used RTV from the factory that was a massive pain to clean off the cover. There also was a lot of surface rust on the differential's mating surface that I steel wool'd until smooth.


I tighened my bolts not super tight at first because I read of people cracking covers by following the less than clear torque specs. I later tried tightening them to 155 inch pounds but that didn't stop the leak.

What did I do wrong here? Is RTV/anerobic gasket maker required (I didn't want to go there after the "fun" of removing it from the composite cover)? Maybe a cork gasket instead?

Suggestions? (the fluid level is low anyway, so I have to redo it soon).

 

[Curious Hound]

Most of what I have read recommends just the liquid gasket. Use good quality and make sure the surfaces are clean. I just used Permatex ultra black on my front this past week. Back in the fall, I used that on both sides of the fiber gasket that came with my diff rebuild kit. But I plan on just using the "goop" and no gasket when I change the oil after the new gears are broken in. I haven't had a composite diff cover. I think I would replace that with a stronger metal cover if it were mine.

Sent from my SM-G920V using Tapatalk

 

[ratdude747]

I don't offroad or anything so IMHO I don't think the plastic cover is an issue if I can get it to seal. If I were lifted then yeah I'd replace it in a heartbeat.

 

[4x4junkie]

I suspect your issue is the paper gasket. The paper compresses when you tighten the bolts and it probably caused the cover to distort.

I would suggest get a metal stock one from a junkyard (I think the plastic covers went away for 1998 & later trucks, I know the '98 XLT I worked on recently had one). Again, only RTV silicone (RTV-Black) is needed for it. Any 8.8" cover should fit it (say from a F-150 or Explorer).

 

[ratdude747]

Resealed it yesterday. I kept the plastic cover but used some of The Right Stuff from permatex to seal it. Upon further inspection the plastic cover has a molded groove for sealant, so clearly the paper gaskets were made for the metal covers (if anything), not the plastic ones.

Time will tell on how well it stays sealed. So far, no more puddles.

 

[KDub57]

I went to change my diff fluid last week and discovered a very small crack on the cover mating surface. I also have (well, had) a fiberglass diff cover. I'm replacing it with a steel one. The crack was covered up by the rtv gasket, but that didn't stop oil from very slowly seeping out.

If the leak persists you may want to inspect the cover for cracks. I found that gently flexing the cover did well to reveal the crack in mine.

 

[ratdude747]

I went to change my diff fluid last week and discovered a very small crack on the cover mating surface. I also have (well, had) a fiberglass diff cover. I'm replacing it with a steel one. The crack was covered up by the rtv gasket, but that didn't stop oil from very slowly seeping out.

If the leak persists you may want to inspect the cover for cracks. I found that gently flexing the cover did well to reveal the crack in mine.

I thoroughly cleaned mine of old sealant; no cracks. As of yesterday everything is bone dry.

 

[KDub57]

I checked the service manual for my 89 BII and it specifies using a "silicone rubber sealant" on the diff cover.

Glad to hear it's working well so far.