StrokerAce03

iTrader: (7)

So our diffs require 2.5 quarts? I'm close to doing a locker install and it looks like I need to go get some more fluid

mds2004

What about when you use synthetic fluids? I run Royal Purple in the rear end and it always leaks. I run black RTV and a gasket. Is the synthetic eating the RTV?

Derek @ EDO

iTrader: (73)

Try using just the RTV, Just make sure the surface is clean before applying.
Ive seen / heard about leaks when you use both the gasket and RTV but ive yet to hear about a leak when using just RTV if applied properly.

Derek

BigD50

I have quite a story for this topic! I feel like an expert after my experience.

I have a 2004 GMC yukon 5.3 and was performing a front and rear diff fluid change for routine maintance. I drained the fluid and put more in the front, easy enough. The back thought is where problems lied. I am not a professional but know a lot and have never hurt my car repairing it. I called around and asked about 3 different shops what they would suggest to use as the sealnt around the diff cover. All said RTV and at the third shop I called the guy gave me a tube of RTV, and i used a gasket scraper to get the old GM AC Delco gasket remains off of it and EVEN sanded it with superfine grit metal sandpaper. I did the smaller type bead and heres where I made my mistake, also put a gasket on. I thought thise couldnt hurt as I didnt use that much RTV. WELL, it wouldnt have hurt except the guy gave me RED RTV that is high temp BUT NOT oil resistant. I torqued everything back perfectly and went on my way then by the time I found out my diff was ruined....3 grand. I saw the cover after taken off and the gasket had failed and the GM tech said you shuldn't use both but if you had used the right RTV you would have been fine. Everyone says RTV but why not go to your dealer and but the gasket and use that? Mine hadn't leaked for 50000 miles. The gaskets are like rubbery type paper and the aftermarket one i bought was just paper.

Dont let this happen to you and remember to use the right type of Sealant or gasket. I say use the gasket as Im sure it wouldnt break the wallet. And as far as fluids make sure you just dont throw any gear oil back there, I had to go to my dealer for the rear fluid because it was the only one they reccomended. It was not sold in stores, I forget the name but I think GM type 2 or something. The front was regular geear oil (still use the right number though!) but the back no. Also the front and back sometimes use either synthetic or regular. So dont make my mistakes and happy differential fluid changing, at last my car is ok. Also my diff pan had a magnet that cathces all the metal shavings, clean this out well too. I would even say maybe buy one that has a magnet on it because there was a substantial amount of shavings, but if you read this truck website then you p rob change it enought not to hurt it or cause noise

Luckily I know some people in the business and I didnt have to pay for it after some red tape was cut and some things were pushed through

nonnieselman

iTrader: (10)

I installed the Eaton LSD in my truck back in '06 and i just used black RTV... same stuff we use on everything else.. well a few months ago i noticed a small oil spot on the carport.. i thought it was the oil port boss for the turbo oil feed...
Well i looked under the back of the truck and noticed the diff cover was soaked...
I had 3 of the bolts were loose. So i went and got some brake cleaner and black RTV..
Cleaned everything and let the RTV sit on the cover for about 20 min so it would gell up.. Installed it and no leaks for several months.

I just used 85w-90 or something, along with a tube of Friction Modifier for the Eaton..

mds2004

Thanks, that is what I will try. Ever since using the Royal Purple I have had problems with leaking. I have tried using the gasket and black RTV about three times all resulting in leaking. This time I will try just the RTV.