Diff Fluid Change-HELP!

[jacal]

I've been having a slow go at my differential fluid change to castrol syntec.

First major problem was that you need 2 crush washers for the rear diff (and probably the other 2 diffs as well). The dealer only gave me 1/per diff and I didn't double check. I put the new washer on the bottom thinking that is the more critical bolt. Was this a good choice?

Then I made my own STUPID error of accidentally "dropping" the little nib on the gear oil container INTO my rear diff! I pumped some fluid through, and I even tried to knock it out with a plastic straw. Finally I put the plug back in, filled half a pint and drained it. I'm not sure what worked but I finally found it in the drain pan. Was the used slurpee straw a risk to the diff in any way?

Then I noticed that the fill plug is magnetic. I did a good job of cleaning the metal bits away. Then I was thinking, why did they put the magnet in the fill plug and not the drain plug? The other bolt is just a regular bolt with the center cut out.

So my big question is: are the 2 bolts interchangeable fit-wise? If yes, shouldn't the magnetic plug be on the bottom to catch more bits? If they are not swappable then I'm ok. If mine are mixed up, I'll have to swap them and try to minimize loss of or re-capture the fresh fluid.

Either I mixed then up (small chance, I was careful about keeping them seperate by dropping the drain bolt into the catch pan) or else they were mixed up when the vehicle had the 32000km service. That would be bad right?

I feel like such a dork!



J

 

[jacal]

One more question:

Can you overtighten the drain and fill bolts? If you do what can happen? I have a torque wrench, but didn't have the adapter to get it up to 1/2" for the 24mm (which I also had to run out and buy, I only had up to 22mm).


J

 

[jacal]

More updates. Read for a good laugh:

On to the front diff - where I stripped the drain bolt. Managed to get it loose. I will order a new one and complete this service. Murphy was here, and he brought the law!



J

 

[hossmaster]

Not sure about the crush washer, never looked or got one after the many changes on my diff. Doesn't leak and not worried about it

No, you didnt do any damage with a slurpee straw. As long as you got out the foreign material from the diff your good.

Yes the bottom drain plug is magnetic and will have very small particles of metal on them. Mine still does after 100k.

No they are not interchangable and you want the magnetic plug on the bottom to collect the metal shavings. Its the diff's filter so to speak.

As for snugging up the drain bolt, I never used a torque wrench, just nice and tight with a breaker bar.

 

[jacal]

Yes the bottom drain plug is magnetic and will have very small particles of metal on them. Mine still does after 100k.

No they are not interchangable and you want the magnetic plug on the bottom to collect the metal shavings. Its the diff's filter so to speak.


What I meant by interchangeable was if they *could* be accidentally swapped? i.e. would they fit if you tried? For example, the front diff clearly can't get mixed up. In addition, the center didn't have magnets at all. So the final answer is that the magnet should have gone in the bottom plug. RATS.


As for snugging up the drain bolt, I never used a torque wrench, just nice and tight with a breaker bar.

I think I overtightened, but all I did was "arm strength" i.e. no breaker bar. I don't think they need to be crazy tight.

Final point: It was interesting to discover that the front diff had previously been OPENED! I can tell by the red sealant. Clearly not factory. Anyway I also noticed that the bottom plug (with magnet) had some shavings but I was really worried because there was a bit of "sludge" coating that plug. I'm glad I changed that fluid. I made sure the front was filled *lower* then the fill bolt hole, just to make sure it doesn't get too much pressure build up. I can honestly say it shifts much faster into 4x4 then it did before.

I filled the centre and rear diffs right to the bottom of the fill plugs, I hope that isn't too much. Ideally they should be a bit lower.

Thanks for your reply.

J

 

[jacal]

faster 4x4!

Well the biggest difference after all the hassle is that:

I can shift WAY faster in/out of 4x4!!! Wow, shifting is now a 5 second affair! Before it sometimes took very long, and never, ever this quick.



J

 

[RickyCRX]

You should always fill differentials to the point where you get a little bit of fluid coming out of the fill hole, then put the filler bolt in.

This is assuming you are on level ground.

It's better to have more than less, IMHO.

Ricky

 

[jacal]

You should always fill differentials to the point where you get a little bit of fluid coming out of the fill hole, then put the filler bolt in.

This is assuming you are on level ground.

It's better to have more than less, IMHO.

Ricky

Oh, I don't necessairly agree with that. Overfilling could put you at risk of too high a pressure inside that diff (even with a vent). When things are moving and all the gear oil is churning, I think things would be more then well-lubed. Especially if you start to get air mixed in.

Ideally, I wanted it a little lower then the fill hole, but as stated, I filled the middle and rear right up to the overflow point.


J

 

[toybox]

Oh, I don't necessairly agree with that. Overfilling could put you at risk of too high a pressure inside that diff (even with a vent). When things are moving and all the gear oil is churning, I think things would be more then well-lubed. Especially if you start to get air mixed in.

Ideally, I wanted it a little lower then the fill hole, but as stated, I filled the middle and rear right up to the overflow point.


J

When I filled mine I kept sticking my finger in to check it and I stopped filling when I could feel it below the lip of the hole. I don't think it matters much though as I only did it that way to keep that smelly shit from leaking out and making a mess.

 

[greasefingers]

Yea 99 % of the people/mechanics just fill it up until it leaks out.

I use the crush washers. No need to use a torque wrench on fill or drain plugs. They do not need to be on very tight. The tranny & transfer cases are aluminium! I just replaced the Diffs, transfer case, tranny, and coolant; this weekend

 

[toybox]

Under warranty I just had to have the seal on the rear diff changed. (it was leaking) I didn't bother giving them the synthetic and now I'm wondering if I should even bother for a while since syn gear oil is so expensive. I feel like I wasted the Amsoil I put in about 10k ago. (I hope that isn't what caused the leak in the seal)

 

[RickyCRX]

Under warranty I just had to have the seal on the rear diff changed. (it was leaking) I didn't bother giving them the synthetic and now I'm wondering if I should even bother for a while since syn gear oil is so expensive. I feel like I wasted the Amsoil I put in about 10k ago. (I hope that isn't what caused the leak in the seal)

I really doubt that caused your leak.... I've been running Amsoil in my differential for the last 25k miles and have pulled trailers in excess of 3500lbs for probably 10-15% of that time and haven't had any leaks or problems.

Ricky

 

[toybox]

I really doubt that caused your leak.... I've been running Amsoil in my differential for the last 25k miles and have pulled trailers in excess of 3500lbs for probably 10-15% of that time and haven't had any leaks or problems.

Ricky

Well I guess I didn't mean "cause" but I have heard that syn oil sometimes can make it past seals that dino didn't. Again just stuff I heard. I'll eventually change it out to syn again but until I have the time and money I'll just leave the freash dino in there.

 

[jacal]

Well I guess I didn't mean "cause" but I have heard that syn oil sometimes can make it past seals that dino didn't. Again just stuff I heard. I'll eventually change it out to syn again but until I have the time and money I'll just leave the freash dino in there.

I wouldn't worry about swapping it just to have synthetic. These are pretty big gears we are talking about, and the oil isn't really subject to contaimination like engine oil is. Really a whole different animal. In my opinion, Toyota is asking for gear oil changes WAAAAY to frequently. I'm even wondering if I'd do synth again, but getting better mpgs makes me want to continue doing the exact same routine.

I keep hearing the "it stinks!" comment...to me it just smells like strong onions. Is that so bad?


J

 

[RickyCRX]

I personally think gear oil is the worst smelling liquid in a vehicle, next to gasoline....

The differential certainly DOES have contaminants that you want to flush out... First of all, it doesn't really hold that much fluid in the first place; second of all, as the gears wear, small bits of metal constantly wear away from the gears and such.... I wouldn't go more than 30k without changing diff fluid, honestly.

In the next couple thousand miles, I'm due to change the tranny, differential, and engine oil on my 4Runner....

Ricky

 

[greasefingers]

Gear oil is the worst smelling fluid on a motor vehicle! The rear diff is huge (almost a gallon of oil) the front diff only takes 1

 

[jacal]

Gear oil is the worst smelling fluid on a motor vehicle! The rear diff is huge (almost a gallon of oil) the front diff only takes 1

 

[RickyCRX]

It's just a good idea to get the metal particles out of the differential oil by changing it frequently. Metal particles floating around and getting between other pieces of metal cause more wear, so if you can keep the ppm (parts per million) to a minimum, it helps reduce wear over the long term.

Having had a differential fail on an S10 Blazer 150 miles from home on the way to a friend's wedding 250 miles from here, I now highly recommend regular diff fluid changes to everybody. (the thing got so hot that the differential cover seal failed, letting out the rest of the fluid, and just completely fried the entire thing.... It was smoking for probably 5-10 minutes after I pulled into a gas station.)

As for changing the plugs.... Just remove the fill plug, then remove the drain plug but VERY quickly put the magnetic plug back in place as soon as you remove the bottom plug.... You can probably get by with only losing 1/4 of a quart or so at most.... Then just top it back up before you seal it back up again.

Ricky