Where is the fill plug on 3.73 D4 Rear End

[BrianV]

I feel like an idiot but I cannot find the fill plug at all. Where should I be looking; again I feel like an idiot. I would think I could fill it without taking the cover off, isn't this true?

Please advise.

Thanks

 

[ExplorerDMB]

how in the world could you take the cover off to fill it? Anyhow, on driver side of the diff (near the pinion) there is a plug that accepts a 3/8s rachet. That's your fill/check plug

-Drew

 

[BrianV]

Thanks I finally after feeling around found it. By the way it's 1/2" on mine, unless I found the wrong plug. I had to use a breaker bar on the truck jacked to get it off.

Unfortunately though I'm still not convinced I've found the right plug because once I got it off I stuck the little bit of my pinky that fit in it and felt nothing but threads. In addition, the plug itself had zero oil on it. That doesn't surprise me because I think it's a little low. However I grabbed a very narrow straw and attempted to stick it in, but I could not get it to go in more than 1/2" or about the length of the fill plug. I didn't feel balsy enough to attempt pouring gear oil in there to have it just overflow all over the place.

I feel so stupid right now since this is so trivial, but seriously something is amiss. Any other advice?

 

[BrianV]

I found this picture of what a drain plug looks like for our car:

For the record that is NOT what the thing I pulled look like. Mine look like a regular 1/2" screw with 1/2" of thread on it.

 

[BrianV]

I keep reading that people put the ratched directly into the fill plug, not use a socket. Obviously I'm not even in the right ball park here. I would imagine the fill plug would be near the top of the rear diff.

 

[BrianV]

Ok nevermind I found it. Grr it was on the wrong side of the axle and I was looking for something to get at with the socket. None the less I got it out with the 3/8" extension on a breaker bar.

I put in about .9 quarts before I basically couldn't get any more in without it oozing out.

THanks a lot for the help.

 

[Hartman]

why the hell would you put gear oil in it without taking the cover off and letting the old drain out?

 

[BrianV]

why the hell would you put gear oil in it without taking the cover off and letting the old drain out?

Well a handful of reasons:

1) It's developed a small leak (don't know how long since I've only owned it 2 months). 2) It's never dripped anything in my garage or on the driveway, but you can see some old oil/sludge built around the bottom of the diff. 3) you can visually see that the seal needs replacing.

Thus, while I determine whether I just want to replace the seal and drain/fill or replace more components of the rear end I wanted to have the peace of mind of knowing the diff is full. Like I said earlier, I put in almost a full quart which is over 1/3rd of the capacity.

I have some gear noise so I think the rear end is a little tired. However I have to decide whether it's worth fixing. My guess is with oil in it it'll run for another 50k+ but it'll just make some noise at 40-50 mph (which is BARELY noticable unless there's no noise in the car at all and you're really listening for it).

I will keep my eye on the seal and see if it begins to leak worse. This isn't my primary car, it's my beater/utility vehicle so it only gets driven like once a week and it's typically to home depot, the lake, or to some bike riding place.

Summary: I just wanted the peace of mind to know the differential was full of oil while I decide what I want to do with the rear end. I bought it used so for all I know it could've been near bone-dry which could cause a sieze up. Now I know it's full and I'll likely check the level every time I change oil or until I notice a visual leak.

Thanks again for the help guys!