Rear Diff leak...

[Nelsonmd]

So I finally got to work on my pastor's 96 LTD today, and I found the source of his rear diff leak. It wasn't a rusted housing like I thought, but rather the lowest diff carrier nut was barely hand tight, and most of the others were only a little more than hand tight. I looked up the torque spec (74Nm, 54 ftlbs) and went at it with my torque wrench. I ran into problems when the lock washer under the nut began to spread apart, and as I tightened, I forced the nut into the lock washer, then the socket slipped on the nut and mangled the nut a bit. I wasn't near the torque spec, but I didn't feel comfortable doing any more. The next nut did the same thing. The rest I just hand tightened as much as I could with a regular wrench and left it as that seemed to not cause the problem

Here's a pic of the nut...

For what it's worth it looks like the leak is mostly stopped, so that's good, but I would like to know what is going on here. I am going to try to find the nuts from my old diff and swap out the mangled one, but I can't find them right now, so it has to stay put for the moment.

I was planning on dropping the diff and putting in some right stuff to re-seal it, but I prefer this route if it works as I can't keep their vehicle very long because it is their only one.

Anyone know what is going on with the nut and washer?

 

[Singtoe]

i think 54 foot pounds is too much. re check your specs. 2nd note- lockwashers are only to be used once.

 

[Nelsonmd]

i think 54 foot pounds is too much. re check your specs. 2nd note- lockwashers are only to be used once.

It's what the FSM says.

Ok and the second point, you are right, but would that cause this issue? Perhaps I will get some new ones and nuts when I place my next order with the dealer.

 

[Singtoe]

It's what the FSM says.

Ok and the second point, you are right, but would that cause this issue? Perhaps I will get some new ones and nuts when I place my next order with the dealer.

FSM says 18 ft/pounds. You over tighten the little washers and squished the snot out of them.

 

[J-money$$$]

If you end up pulling the third i would recommend ultra grey rtv. Make sure you scrape and clean the surfaces first or you can expect to see it leak again

 

[02SE]

FWIW, my FSM states:

W/O diff lock 54 ft·lbf

W/ diff lock 18 ft·lbf

 

[Singtoe]

FWIW, my FSM states:

W/O diff lock 54 ft·lbf

W/ diff lock 18 ft·lbf

Maybe he has a diff lock.:flamethrwoer2:

Do you have an actual paper FSM or did you down load the free one?

 

[kball]

My paper 97 FSM says the same thing as the online FSM. I wonder why there's such a difference in torque, it's the same number of nuts...?

 

[J-money$$$]

54 ft lbs seems a little high for a 10 mm stud...

 

[Singtoe]

My paper 97 FSM says the same thing as the online FSM. I wonder why there's such a difference in torque, it's the same number of nuts...?

Must be a typo. I know that the Tacoma without the E-locker has larger studs that hold the diff to the axle housing. So those studs would require a higher torque spec. The Tacoma with E-locker uses the 8mmx1.25 studs just like the 4runners non-locking diffs.

So the torque spec should be same for 4runners using e-locker or not. 18ft/pounds.



Tightening a small 8mm bolt past 40ft/pounds would likely strip out the housing, break the stud or strip out the nut.

 

[Nelsonmd]

Hmmm, this is interesting. It is not a locker. Chiltons had 18 and 54 listed, but they didn't distinguish when you use one or the other. 18 seems very low to me. I'd believe that 54 is too much. I could see 18 when you are just setting the gasket, but I would think you would want a little more preload once the gasket is hardened.

 

[Singtoe]

18 is the standard torque for that size stud. A grade 10.8 goes up to 24 ft/pounds. Don't forget, there ten of those studs that hold the diff on, so everything is nice and tight.



The paper gasket shouldn't harden but it can it can tear very easily.

 

[Nelsonmd]

18 is the standard torque for that size stud. A grade 10.8 goes up to 24 ft/pounds. Don't forget, there ten of those studs that hold the diff on, so everything is nice and tight.



The paper gasket shouldn't harden but it can it can tear very easily.

Right, I was thinking if you put an FIPG in instead. I bought a bottle of right stuff thinking that's what I'd do.

 

[Singtoe]

Right, I was thinking if you put an FIPG in instead. I bought a bottle of right stuff thinking that's what I'd do.

I agree. I used RTV sealant when I retrofitted the e-locker to my non- locker housing.

With over tightening the the studs as you did, the surfaces could be warped now and a paper gasket would never seal it again.

Definitely get some new nuts and lock washers and use 1/8 bead of RTV silicone on the mounting surface bolt it up.

 

[legokcen]

Here is a torque spec chart for different bolt sizes and grades.

US & Metric Bolt Torque by Grade

I would assume what we have is similar to a grade 5 (8.8 in metric) fastener.

 

[Nelsonmd]

Well, to update this thread, I finished my work. Here is the list of everything I did:
Tightened diff carrier bolts
Stripped and POR-15'd the diff cover
Refilled diff with oil
Replaced and adjusted rear brake drums
Bled entire brake system
Seafoamed the engine
Seafoamed the engine oil (looked in at the cap saw alot of hard gunk in there)
Removed parking brake hardware and pressed out the corroded in pins
tightened throttle cables

I checked the diff for any leaking, and after 72 hrs, I saw no oil whatsoever. I found this to be a very amusing point because they had taken it into a shop (A meineke franchise that is trusted by several friends, and seems to be an honest shop, at least the owner is) and the mechanic there told them that to fix it would be very expensive, and not really worth it for the value of the vehicle (it's a 96 LTD auto with 158k, in slightly rough shape). Turns out it was a free fix. Kind of a big difference there.

Anyway, I am going to order at least a couple new diff carrier nuts and washers from the dealer, and replace them when I get around to putting the parking brakes back on. At least for now I don't think I am going to pull the diff off. If they get leaking again, perhaps I will, and be very careful of the torque, but until then, hand tight with a standard socket wrench seems to be doing the trick.

I am seriously tired of working on cars at the moment. I spent most of my long memorial day weekend working on them, so I think I am just going to enjoy mine for a little while. At least until July when I get into my new apartment and have a real garage.

Thanks for the help guys. Good to have found a typo in the FSM and chilton/haynes guides.