I'm in the process of changing my rear diff fluid. I have removed the old fluid, cleaned the diff cover, and RTV'd the seal around the differential. I bolted the cover back on and tightened the bolts until the RTV just started to squeeze out the sides, as per the instructions on the tube. The tube then says that the RTV should set in an hour and then you can tighten the bolts up all the way, but it has been well over an hour already and when I tried to screw one of the bolts back on it came gushing out, all wet. How long do you guys usually let the RTV set before torquing down the bolts? And also, after tightening the diff cover, how long do you wait before driving the truck again? Thanks.

-Chris

 

drain reseal fill and drive.I never had a prob. If u have a l/s rearend make sure to use an additve with your gear lube.other whys u will bake the l/s

 

Well, I have never heard of allowing the RTV to set up before you torque the bolts down. I generally follow the manual (Chiltons, Haynes etc.) and those publications advise you to torque the bolts to spec. immediately upon putting the cover back on. The fact that you had RTV oozing out after torqueing the bolts seems to tell me that you perhaps had a bit too much of a bead laid down? Regardless, I would tighten the bolts to spec. and allow the beast to sit overnight maybe. Then fire it up and take it for a good spin - long enough to heat up the diff. fluid really well and carefully check for leaks. If you have any leaks, even a really small one, you will have to start over again. Just my .02 though - YMMV.

Cheers!

Mike

 

The tube says to let the RTV set first, that way it creates a sort of gasket and then you TORQUE down on that gasket to create a seal. If I were to torque it down as soon as I applied the RTV it would all just gush out in and out of the differential. The tube actually instructs you to put enough RTV so that it comes out the sides a bit when you finger tighten the bolts, that way you get a nice solid gasket out of it. Has anyone else done it this way?

-Chris

 

Well I just went over and tried to torque one of the bolts down and the RTV came squishing out, still wet. I can't believe that it would be a very good idea to put the RTV on and immediately torque the bolts because then you've compressed all of the RTV right out of the seal, therefore you've got nothing between the diff cover and differential. Also, to the first guy who replied, you torqued the nuts immediately, filled it with fluid and then drove the truck right away? If you did that, wouldn't the RTV squirt INSIDE the differential, and then mix with the fluid...? Doesn't seem like a good idea to me...

-Chris

 

This is what i would do. Apply a bead of RTV all the way around the differential on the COVER side. Then i would smooth it down with my finger and just let the cover sit there for about 5-10 min. Then put the cover on and call it good. RTV is pretty forgiving. This is what i did when i installed my water pump and my thermostat. No leaks yet.

 

Unfortunately the RTV is already on and setting, and I have to drive the truck back to my apartment tomorrow morning, and the truck is at my neighbors house on his lift right now. So I'll just have to make due tomorrow, and if it leaks then I'll have to do it again next weekend. Thanks for the advice.

-Chris

 

to be honest with you i think you will be just fine. On my 85 i can recall just throwing some RTV on the cover and bolting it on and throwing fluid in right away with no problems.

 

Never heard of letting it sit and retourqing. If it is squishing out after an hour, you used way too much. Thin even coat, let it sit couple minutes, put it on, fill it, drive it.

 

Went back to torque the bolts this morning, RTV was pretty well hardened, couple soft spots. Torqued the bolts down and filled 'er up. No leaks, runnin' great. Thanks guys.

-Chris

 

I beleive this is the "Proper" way to do it. Even though 90 % of the time people just slap it on and it works.

 

Are all of you guys talking about using RTV only without a gasket?

 

Yes, no gasket. Allowing it to set before torquing it CREATES a gasket.

 

I always put it on both surfaces, smooth it with my finger, and torq it down right away. never had any problems. i dont think that rtv is intended to "make a thick gasket" just fill in the in-perfections inbetween the surfaces. Just my .02

 

I agree, I always thought that RTV was just to fill in minor imperfections and make a very thin gasket. I use a thin bead and slap it on right away. I usually don't refill for an hour or so, just to give it a chance to harden up.