Diff oil change

[MorrisJohn]

I decided to change my diff oil today. It’s a ‘57 Minor 1000. I drained the oil off from the drain plug then using a syringe squirted in approx 800-900ml of EP90 gear oil into the filler hole circled. (Probably nearer the 900ml mark).

For some reason I thought the diff was just filled until the oil started coming out the filler hole?

I believe it’s meant to take 1 1/2 pints, is that correct? That would equate to 852ml.

Having not done this job before if anyone can cast an expert eye on the colour of the old oil and pass comment it would also be appreciated.

[philthehill]

That is not the filler hole!!
The filler hole is either in the nose of the diff or halfway up the rear of the diff banjo.
The oil is drained by the drain plug at the bottom of the diff banjo.
The oil shown in your photo does not look too bad and is reasonably clean.
Make sure that the oil is EP80/90 GL4.
The diff is filled with oil until it comes out of the filler hole.
If you do not have a filler hole in the rear of the diff banjo or in the nose of the diff someone has fitted a 1098cc diff to a 948cc axle casing.

[MorrisJohn]

That is not the filler hole!!
The filler hole is either in the nose of the diff or halfway up the rear of the diff banjo.
The oil is drained by the drain plug at the bottom of the diff banjo.
The oil shown in your photo does not look too bad and is reasonably clean.
Make sure that the oil is EP80/90 GL4.
The diff is filled with oil until it comes out of the filler hole.

Oh dear. Glad I asked. What is that hole for where I’ve put the oil into? Do I need to now drain it back out of there?

[philthehill]

The capacity of the rear axle is 0.85 ltr.
I would not drain out the oil unless you have used oil other than EP80/90 GL$.
Do you have either the filler plug in the diff nose or rear of the axle banjo?
If you do not - as I said above the diff has been changed.
The hole you are using to fill the diff may have been purposely made or is/was used for locating the axle breather.

[MorrisJohn]

The capacity of the rear axle is 0.85 ltr.
I would not drain out the oil unless you have used oil other than EP80/90 GL$.
Do you have either the filler plug in the diff nose or rear of the axle banjo?
If you do not - as I said above the diff has been changed.
The hole you are using to fill the diff may have been purposely made or is/was used for locating the axle breather.

I used the correct oil (EP90). If I’m reading this correctly then the oil added will have ended up in the correct place anyway?

I’ll get under the car, have a look and take a couple of photos shortly.

[philthehill]

The oil must be EP80/90 GL4 not just any old EP90. If you fill with the wrong oil the bronze bearings in the diff will get eaten away.

[MorrisJohn]

The oil must be EP80/90 GL4 not just any old EP90. If you fill with the wrong oil the bronze bearings in the diff will get eaten away.

Yes, I used Duckhams EP80/90 GL4.

I believe I have located the filler hole. Photo attached.

Will the oil have ended up in the right place where I put it in at the top? I could open up the filler hole to to check the oil is filled to that level?

[philthehill]

That is the filler plug.
I would clean all the muck off around the filler plug. Remove the plug and see if oil flows out. If it does leave until no more drains out. If nothing drains out fill until it does. Leave a minute to settle. Refit the plug and jobs done.
The oil that you have put in the axle through the top hole will flow to where it is wanted and any excess will drain out of the filler hole in the diff nose.
EP80/90 GL4 diff oil will do nicely.

[MorrisJohn]

That is the filler plug.
I would clean all the muck off around the filler plug. Remove the plug and see if oil flows out. If it does leave until no more drains out. If nothing drains out fill until it does. Leave a minute to settle. Refit the plug and jobs done.
The oil that you have put in the axle through the top hole will flow to where it is wanted and any excess will drain out of the filler hole in the diff nose.
EP80/90 GL4 diff oil will do nicely.

Perfect, thanks Phil. Good learning experience today, but I’m happy it’s basically ‘job done’ (in a roundabout sort of way). I’ll know for next time.

What threw me off course was watching a YouTube how to guide but the differential was different to mine and I didn’t spot that filler hole. I checked the Haynes manual too, but it wasn’t clear at all.

[MorrisJohn]

I did as you said Phil. There was a little fresh oil tricked out and eventually stopped, so only slightly over filled I think.

I’m guessing you want the car as level as possible when doing this? My car is sitting slightly higher at the rear just now because I have it on axle stands. Just high enough to give me a little clearance to get the rear wheels off with a few mm clearance.

Is this likely to much such a difference that I’d need to top it up again when it’s perfectly level?

[philthehill]

There will be very little difference in the oil levels whether the car is level or as is shown.
I would just re-fit the filler plug and enjoy the car.

[MorrisJohn]

I would just re-fit the filler plug and enjoy the car.

Done Many thanks for your help.