Gearbox oil change

[Zac]

I have a 94 4Runner with a manual gearbox and want to change the oil. I've had a good look at the box from underneath to try and identify the fill and drain plugs. I have found a 10mm hex head plug near the top of the box on the off side of the vehicle, which I assume is the fill plug. I'm confused however about the drain plug. About a third of the way up the box on the near side of the vehicle is a 24mm brass coloured plug. There’s also another identical plug almost at the bottom of the box on the opposite side. I've tried both with a spanner and been able to start to loosen the higher up of the two, but have been unsuccessful in being able to shift the lower one.

Can anyone tell me:
1. Have I correctly identified the fill hole?
2. Are both the lower two plugs drain points, and if so why two and which one do I use to drain the box?

[JimL]

No you've not got the right fill hole, stay away from the hex heads!

The drain hole is easily found right underneath the gearbox, almost directly underneath the gearstick area. You're looking for a regular bolt with a big mutha of a head and yet it only takes a few winds to get it out.

The filler is halfway up the gearbox on the nearside and the filler bolt is identical to the drain one.

I think they are 24mm and listen to this advice: if one is jammed tight and wont open with budget tools i.e. draper or any other market quality !!!!e, the one that eventually did it for me was the draper expert hi-torx half inch socket - everything else wrung the edges.

Dont forget to change the oil in the transfer case which is practically the same job 15 inches further back, only the filler is probably at the rear of the t-case.

**edit** if you look at the tranny in the pic, you see the filler plug in the brown painted area just below the yellow, its clearly on the side and above the hex plug

[Zac]

As I’ve already been successful in loosening the higher of the two 24mm plug bolts, (the one on the passenger side, which is in the lower third of the box), I have now taken it out. I was taken a bit by surprise when a good litre or two of oil flooded out before I could get the plug back in.

I decided to take out the hex plug near the top of the box. I made a home made dipstick from a piece of wire and poked it down into the box. As there was oil on the dipstick when I pulled it out, so I’m assuming that I’m dipping the remaining oil in the box

Now I’m really confused as there are no other plugs between the one I’ve taken out that oil poured from and the upper hex head plug where I dipped the oil from. Although you suggest that the hex plug near the top of the box is not the fill point, I can’t see where else oil could be put in order for it to be able to flood out when I removed the plug in the lower third of the box.

I’ve still not been able to get the plug on the lower edge of the box undone, but I’ll try your suggestion.

I’ve got an Australian Haynes manual for the 4Runner which is no help at all, but it does say that the 5 speed manual box takes 3.9 litres of oil, I’ve also checked this on the Valvoline web site and they quote the same amount. I reckon that if I was to fill the box from the opening I dipped the oil from, given there is a fair bit of kit in the box that’s taking up most of the space, it would probably take about that amount of oil. But I still reluctant to do it given your comment about staying away from the hex head plug.

HELP!!

[JimL]

The hex (or are they torx or something) ones usually have a spring and a ball bearing behind them and arent for filling coz the level is set purely by filling with gear oil until oil spills out thru the hole you are filling at i.e. the 24mm plug.

The only way I can figure that they got more in than they should have was they filled thru the top hole where the gearshifter bolts down onto the box.

By the way it was the side plug that I couldnt shift with cheap tools coz its at an awkward angle and the spanners just slipped off and rounded the edges so I bought the good socket.

*edit* tomorrow I'll try and get a pic of whats behind the 'hex' one for you, and sorry that !!!!!! pic above is so big but I cant be arsed with the downsize

[TonyN]

The big nut on Jims pic is the fill level mark, the drain plug is on the underneath, right in the middle of the gearbox.

Oil needs to be 5mm or less lower than the level of the fill plug. Just stick your little finger in the hole to find the oil level.

When filling, when it starts to run out the hole, bung the nut in.

Its not a good idea to undo the hex nuts, they normal hold springs and ball bearing in place for the shifter rods.

[Zac]

As I couldn’t get my head around why I got flooded with oil when I undid what now appears to be the fill plug, I called Toyota’s incredibly expensive, premium rate (£1.50 per minute) technical helpline. It seems that you guys are right and the higher of the two 24mm plugs is the filling point, although I still can’t see how you can get 3.9 litres of oil in the box using that hole. According to the Toyota technical people, the 10mm hex plug near the top of the box is just a blanking plug.

Thanks for the assistance in getting this one sorted out.

[JimL]

although I still can’t see how you can get 3.9 litres of oil in the box using that hole.

Its easy when you have the right contraption like they would in a garage, but for you its the squirt from the bottle method and you only get about 300ml in each bottle full if youre lucky

[Guest]

Its easy when you have the right contraption like they would in a garage, but for you its the squirt from the bottle method and you only get about 300ml in each bottle full if youre lucky

Use the Pump action spray like I used for the front diff oil. I got a 3 litre one but you can get a 5 litre one. Makes it a doddle.

Cheers