Flange Nut Identification

So a few days ago I noticed a buildup of grime on the drivers side of the engine bay, specifically centered around the front differential breather tube. Well I crawled under today and checked for any sort of block in the breather line, and while removing the line this 14mm flange nut just fell onto the ground. I'm operating on the theory that my front diff was overfilled slightly, and a recent trip to Big Bear, CA at elevation with 4x4 led to a small puke. However, this flange nut is covered in the same sludge, and quite a bit of it. It's possible that the nut might be apart of the issue. I couldn't for the life of my find where it would go. Any 1st gen experts out there care to lend some insight on studs that require a 14mm socket for my mystery nut? Probably a thread pitch of M10 x 1.25 or so, not certain yet.

Truck is a 1995.5 SR5 Extended Cab 4x4 3.4L. First photo shows where I've been having issues, and also where the nut fell onto the ground. Then there's my grimey nut

 

If it came from that area, check maybe the bottom bolt of the alternator?

 

Kinda looks like a trans cross-member nut

 

Thanks for the ideas guys. Honestly I figured with the skid off and in a localized area, I’d be able to find it. It’s been raining so I haven’t been able to go out and investigate further.

It’s possible, i’ve been there too. This definitely looks like an OEM nut, I would rest a bit easier even knowing where the replacement is located.

I’ll look around the alternator mounting, accessory systems, and cross member tomorrow. It’s a somewhat uncommon nut, I was hoping It would jump out at someone. Thanks again!

 

Unless you have some super giant hands, that is not a 14mm nut. It looks to be a 10mm nut.

 

Socket size is 14mm that goes over the nut. 100% sure about that.

I know that's not the correct way to identify a nut, you're right in that the thread pitch is probably like M10 x 1.25 or something.

Edit: I'll get the pitch tomorrow, that would be a more useful indicator of where to look. I'm assuming this nut mates to a stud and not a hex bolt, from my limited experience.

 

It could have been dropped !

Exhaust Manifold Nuts are M10x1.25 also the crossover pipe nuts

I am not sure when the Stainless Locking M10x1.25 nuts were put into use .

Have you had your Truck since new ??

 

Thanks for the info! I need to check the thread pitch to be certain, but I was checking the exhaust manifold nuts and they seemed to be a 12mm socket? It’s possible that it’s M12 - x.xx but it’s definitely a 14mm socket head.

I have had the truck for a little over a year, the PO had owned it since new and had toyota exclusively do the service, so who knows the quality of work over the last 23 years. Besides the valve cover gasket leak (servicing next week, hopefully minimal sludge) the truck is in perfect condition and drives like new.

 

It's not a wiper arm nut is it? I can't check mine right now to confirm.

 

Pretty sure wiper arm nuts are brass colored.

 

OP, look for a missing nut on the driver's side of the fan bracket, just below the upper timing belt cover. On mine there is a nut at that location identical to the one you pictured.

 

Is this the nut you're talking about? Come to think of it the current nut/washer on the stud doesn't look factory IMO. The outer diameter of the washer is proud of the fan bracket. Pics for reference of the current nut, closeup, and the mystery nut threading on to the stud. Plus in the parts diagram its not shown as having a washer, but rather a single flanged nut. You might have solved it...! Makes a bit of sense too as it was a Honda dealership that performed the service of timing belt/water pump. They probably put the nut down on the fusebox and lost it? So much speculation hahaha. If someone could provide a picture of theirs it might clear things up.

 

Yup. You appear to have found the OEM nut that goes there.

 

As requested.

 

There it is! Thank you so much for your help, I owe you a beer!

I guess the good news is while I was doing this I also installed a fuel filter in the front diff breather, did the rear diff breather mod, greased the driveshaft and greased my upper control arms.