hey, need some help. My dad's '84 Ram Van 250 is making groaning sounds in the back, My dad says it's the differential fluid that's begenining to breakdown, and needs to be changed.

I never change differential fluid before so forgive me for clarifying but is this correct?

Reading the how to's

1. Remove the bolts on the bottom half of the pan.
2. Pry the bottom slighty open with a screwdriver to drain.
3. Once empty, remove the top bolts and clean the surface of the old gasket and place new gasket and pan back on with bolts and refill.

Is this correct? Am I missing something?

Also what type of replacement fluid should I get and how much should I put in?

I plan on either doing it late this afternoon or tomorrow.

Any help or advice is appreciated.

 

The instructions sound right even though your Dad's diagnosis doesn't. Usually once you hear groaning it's too late, damage is done.

My only suggestion is to first make sure you can remove the filler plug if it's the threaded kind. I've seen it happen where someone drains it, then cannot get the fill plug out. You can't even drive it anywhere for help at that point.

 

It comes and goes, sometimes it's loud other times quiet. When it's cold it's fine and when it's hot it just groans every few 100ft. I started calling it "The whale." Frankly we don't drive it much and it's been sitting for quite while and that fact that my dad doesn't remember when the last time he change the gear oil in it. He figured that the fluid started to breakdown. Cheap to replace, quick to find out. If it's something else then we'll just drive it til it's dead. I'll check to make sure I can remove the fill plug, before draining it.

Thanks for the tip.

 

http://www.ringpinion.com/DiffList.a...=Diff&TypeID=2

You likely have the 9 1/4 inch or the 8 1/4(actual 8 3/8).

They both take just over 2 quarts.

I'ts good to change the gear oil , but make sure the U joints are not the source of the noise first. Try moving the driveshaft up and down and side to side looking for slop in the u joints.

Some people add 85w 140 gear oil to a worn diff.

75w 90 is the normal weight one would run in a healthy diff.

You can suck the fluid out through the fill hole, but it is better to remove the cover and clean the magnet and see what it looks like in there.

 

I'm draining now, oil looks brown/black with a whiteish tint, a bit thick and smells really bad.

I don't think it's the U-joints, We had them replaced in 2002. The whale drives, shifts and rolls smoothly. But it could be them, does making a loud clanging noise when shifting to reverse warrant such. I know it's not the transmission but more like the drive-train. It's never affected the performance of the van though.

Anyways...
I got three Lucas 80W-90 after finding my differential is a GL5 which uses 4.5 pints, non-slip-lock and got a new gasket. The cover/fill plug is rubber and has went bad, it's leaking gear oil, but couldn't get a replacement today so I'll probably use the old one and not drive much until the new one gets here monday.

 

Easy enough to just run down to Autozone and pick up an aftermarket cover, a new gasket & and then fill the differential. Not really a major emergency.

 

Just don't fill it quite all the way up and it shouldn't leak much, if any.

 

Not all differentials have the fill hole in the cover, and if the van is a person's only transportation, how are they supposed to run down to Autozone!? It's just good practice to check it before draining, period, end of story.

 

After the fluid change, I noticed the rear end is more responsive, the noise is still there just more dampen in the back now, doesn't do it often. Actually it makes the noise more apparent in position, sounds like it's in the middle near the front. Before it didn't have pattern after the fluid change, it seems to do it when accelerating up a ramp or acceleration from a dead stop. Cruising around 30mph makes the noise consistent but fades out if you go over 31/32 or under 30. Took it up to 60 on I-4, it's quiet. Deccel or braking doesn't make any noise. It's not the transmission, it shifts smoothly and has no problems that I'm aware of.

So that leaves one thing, the drive shaft and it's u-joints. Well like I said my dad and I don't want to spend money on the whale, because it's a rust bucket, it's got few other severe problems like the E-brake cable is broken, fuel sending unit is broken, and few other things... Gas is becoming a pain in the ***.

We'll just drive it til it dies. At least I know the differential is ok is now serviced.

 

The noise may be the tires. Cargo vans can be bad about transferring the road noise of the tires into the van itself.