NissanDiesel Forums

I pulled this plug out of the top of my transmission while searching for the dipstick. I'm wondering if this is what I'm supposed to measure the fluid level from, or if this is just a filler tube? I noticed my speedo cable was loose and had sprayed oil everywhere, so I need to fill it back up.

Looks like a breather....

Agreed. it's a vent

What transmission are you checking ?

The plug is solid, no holes for venting as far as I can tell. Its a 1982 720 long bed with a 5speed, 2WD.

There will be a baffle in the trans under that tube. It allows for the expansion of air in the trans from hot to cold, and the baffle stops fluid from being expelled should you have the truck on a steep angle, etc etc.
The trans fluid level is checked by removing the pipe plug on the side of the transmission. The fluid should just be at the threads of that plug once removed, or even trickle out a bit. Some guys put the truck on a ramp on the left side to get a bit more fluid in. Too full of course is not recommended. The plug will be similar looking to the plug at the bottom of the trans.
A good trick to remember when removing pipe plugs, ( or any pipe thread in general ) it to tighten it slightly first before trying to remove it ( just so it moves ) . Pipe threads are tapered and they get bound up with residue and gunk over time. By tightening slightly you break this stuff loose and it will wind out much easier that trying to just loosen and round off the edges.
Filling the trans is done through the same plug that you remove to check the level.

HTH

Paul

Had to tap the wrench with a hammer to get the plug to break free but I found it! So much easier when you know where to look thanks Paul.

Couldn't feel any fluid in there, online I read that it takes 75w-90 gl4? 3.5quarts? I'm in California so it doesn't get too cold, but sometimes there is frost at night.

There is something most people don't know about pipe plugs and especially those threaded into aluminum. That 'something' is that most poeple -including mechanics- OVERTIGHTEN pipe plugs. Whatever torque is applied to the plug at installation grows to almost double after the transmission heats and cools a few times after the plug is installed. If you tighten a pipe plug to, say, 40 foot pounds, it will take about 80 to remove after a few heating/cooling cycles.

With that in mind: Use teflon tape and resist the urge to tighten the plug as though it is holding a truck tire on a tractor trailer.

N_R

Get 4 qts of the Amsoil Manual Trans 75/90 GL 4
Or the Red Line MT 90. ( I use Red line but both are very good )
I have no trouble here in the Great White North in winter and it's so much better than the dinosaur oil in those temps. Ease of shifting etc.

The "Tighten Method " of taking pipe threads apart or open has never failed me.
Teflon tape is good too but I have some PST ( made by loctite) and it's also a sealant so you need only to go a touch ( 1 turn approx ) over finger tight.
As Ranger said, a lot of people over tighten, and then add dissimilar metals to the equation and it gets worse.

Take the drain plug out of the bottom and then fill with Auto Trans fluid, jack the rear wheels and start it and run it through all the gears and up to approx 40mph. Let it idle for a few minutes in N
The auto trans does a good job of washing the baulk rings and the surfaces of the synchro drums, and all the brg.
Makes the brass grip again etc.
There is a magnet on the lower drain plug and will give you an idea if there is anything nasty happening. or about to happen inside the trans.
Drain the auto fluid and install either the Amsoil or the Red Line.

Then, just keep an eye out for leaks. The reverse light switch can start to leak and they are still available from Nissan. I have a part number here someplace. Can be changed on the truck without too much drama. Drive the pass side up on ramp and you can change it without losing more than teaspoon or less.

Good Luck

N_R, sounds like the same thing people have with oil-filters! I'll try the teflon out.

plenzen, Sorry I figured the only 5speed was a manual, mines a manual transmission. Or do you mean use auto fluid to clean it out and then fill it normal?

BTW: thanks for all the help so far! Was worried about being able to find a community for this truck.

Yup that's what I mean.
Use the auto trans fluid as a wash.
Then drain and use one of the oils I mentioned.

Well the truck is jacked up and I've got all the oil, but the drain plug is wonderfully stuck. The socket is stripping the inside out so I'm going to get an impact wrench, I've been wanting one for a while. Hopefully that will work.

Its 1/2" drive right?

You're going to get into trouble with this thing real fast if you have to ask what size it is (No offence intended; just my observation!)

If it is a half inch square 'hole' like mine, then, yes, it would be a 1/2 inch square drive. And using an impact on it is literally the last thing you want to try.

What has worked for me very well is to use a johnson bar; power bar; strongbar, or whatever they call those things where you are.

What I do is make sure the hole in the plug is cleaned right out. Then, I put the square drive of the johnson bar into it. Then, I pump up a bottlejack underneath the square tip of the johnson that's now in the plug and put some pretty good pressure up against it. (The johnson handle is horizontal, of course) That will hold it right up in there and keep it from jumping out when you pull on it. You could likely also use a good strong ratchet drive instead just so long as it will take a strong pull on your part. Be careful that the head of the jack stays in place under neath the square drive. The plug should now should come out with a firm steady pull. If not, we'll think of something else.

Its chill, just wanted to be sure it wasn't some strange metric size. I'll see if there is any grit in there. The breaker bar i was using was chewing up the plug and not turning it.

I'd try out the jack trick but we ended up topping off the level so we could check an oil-leak. The leak is now ridiculously bad (oil is flowing out the breather tube). So the transmission is going on the backburner I think :/ Its looking more like a mistreated lemon every day

You didnt try the "tighten" method did you ?

Ipper: I hear you about those trannys. I went through two of them in a year in my truck. I now have no spares:-(

N_R