new here, and I broke something between the engine and the wheels

[millican]

I found this forum searching for any helpful clues and thought I'd sign up, and post.

I was told by a mechanic a few weeks ago that the throw-out bearing was going out. He said it still has a couple of years and if it were his, he wouldn't replace it yet. Today, I thought I heard a whine while driving through Oklahoma City, The whine is like the sound an electric forklift makes. I wasn't sure since it's hard to hear much of anything over the diesel engine. About 30 miles later, there was a loud clunk, and then coasting. I coasted onto the shoulder and stopped. I know that just saying loud clunk isn't descriptive, but that's what it was. It will go into all of the gears, but when I start to let off the clutch, it just sounds like gears not meshing. There is no movement. In gear, the truck can't be pushed. In neutral, it's fine. With the engine off, it's inconsistent with shifting. It might go into a gear easily, or it might not go at all. I had it towed to a motel. I'll either rent a u-haul and tow it the rest of the way to Tucson tomorrow or have it fixed here. Only thing is, I have no idea what to expect for a repair in terms of cost and time. Either way, it would be nice to be able to fix it. Any ideas?

I'll also confess that I was carrying about a dozen boxes of books in the pickup along the interstate 540 in NW Arkansas at the start of this trip, which has some nasty long steep grades that I took at about 45 to 50mph in 4th gear.

[wayno]

I know that you might not have an answer to this question, but I will ask anyway, when it was in neutral with the clutch out while running did it make noise, did that noise go away when you pressed the clutch in?

Right now does it do the same thing, clutch out it makes noise, push the clutch in and the noise quits?

 

I hate to tell you this, but that clunk you heard was likely the cluster gear bearing in the transmission destroying things as it exploded, unfortunately you likely are not going to get this fixed fast, it really depends on if the transmission case cluster gear bearing hole and front steel cover were destroyed/damaged, if they were, then you only have about two options, one is to have the hole punched out to the larger sized 85/86 bearing, and get another aluminum front cover from another 85/86 transmission, or find another good diesel transmission.

Even if your case is good, you still likely are going to need to find another longshaft 5 spd. transmission out of a 720 to put your diesel case on if it was not screwed up.

When you hear that noise that goes away when you push the clutch in while sitting still, you need to quit driving it, as diesel transmissions are hard to come by, as everyone wants them, diesel guys want them to replace their bad trannys, and the roadster guys want them to use Z car transmissions.

 

Let me know exactly what noise it makes with the clutch in, and clutch out, if it makes a squeeling noise when you push in the clutch, that would be the throwout bearing.

[millican]

It was making the squealing noise when pushing the clutch in. I was told that it was the throw-out bearing, but it was still OK.

I just went out and started it to check for noises now. In neutral, there is no longer any noise with the clutch in or out. Would the throw-out bearing damage the transmission, or would that be an unrelated problem?

[wayno]

Did it make noise before when the clutch was out in neutral?

What I am getting at is when the clutch is pushed in, the input shaft shaft of the tranny is not turning, so no noise will be created by the tranny, but if the clutch is not pushed in, then the input shaft turns, if the bearing is bad, then it makes noise.

If it was making noise while driving down the freeway in gear, that makes me think it is the transmission, because you are not pushing the clutch when driving down the freeway.

Since it starts, it is not likely a flywheel issue, and since it don't move at all anymore I am assuming, then it is either the clutch disc, the transmission, the driveline, or the rearend, if you put it in gear and let out the clutch, is the driveline turning?

Just try to figure out what has failed without taking it apart, if it squeals when the clutch is pushed in, then it makes me think it is the throwout bearing, but it is not likely the TO bearing going bad while driving down the road would stop the truck.

So check the driveline, U-joints, just check everything you can before taking it apart, unless you are home.

[Sick720]

Sounds like the small bearing behind the front cover on the transmission, good luck man.

[Sick720]

Mine threw that bearing and it wouldn't do anything, except grind when i let the clutch out.it would go in every gear too.

[Sick720]

And these transmissions ain't fun to get out by yourself, I'm really sorry to hear that man, i know the feeling.

[millican]

It will probably get towed behind a Uhaul and put into a shop then. I've made repairs to the transmission in my wife's Saturn, but none of them required dropping the transmission. I live in an apartment, and there's only so much I can do in the parking lot as far as repairs go before drawing unwanted attention from the manager.

[wayno]

It will probably get towed behind a Uhaul and put into a shop then. I've made repairs to the transmission in my wife's Saturn, but none of them required dropping the transmission. I live in an apartment, and there's only so much I can do in the parking lot as far as repairs go before drawing unwanted attention from the manager.

Somehow you need to drop the transmission and see if it is indeed the tranny, otherwise it will just sit till you either give up on it because the case got wasted and you cannot find another one, or you sell it to another person, or a scrapper.

Putting it in a shop might become an issue that will have to be dealt with fast, as there could be storage fees ect. if you cannot find the parts you need fast.

If you can find a way of dropping the transmission yourself, I can walk you through getting it back on the road, as long as the case is not buggered up beyond repair, but you will need another 80-83 datsun/nissan longshaft 5 speed transmission, all 720 2wd kingcabs have what you need, longshafts are 31 inches long from the bellhousing to the tail, and you possibly might need the front bearing cover from an 85/86 720 5 spd. transmission, it all depends on if the case is damaged badly.

[millican]

It turns out that it wasn't without all gears. 4th still worked. The shop mechanic suggested that it was "fused" with that gear in place. I felt really boneheaded when he mentioned that. I was under the hood before leaving with the intention of checking the transmission fluid and got distracted. (So how many are going out to check theirs right now?)

I wish I could take you up on your offer to help. I love doing as much as possible myself so that I can learn how it works. I don't have the facilities or tools here to do the work since I'm in the middle of moving. It will cost about $700 for the shop to put in another transmission. That's not too bad. I think the valve body solenoids alone in my wife's transmission cost almost that much. I will ask the shop mechanic to save the old parts though so that I can see what they look like. I'm sure it's not pretty, which is all the more reason I want to see it since the damage is done already.

[wayno]

You have another datsun 720 diesel transmission?

[millican]

found one for 450

[wayno]

found one for 450

 

WOW, that was good timing.

 

The reason that 4th works is because it doesn't go threw the cluster gear, it's like direct drive.

Next time you hear that noise when the engine is running, and in neutral with the clutch out, quit driving it.

Don't throw away the front diesel case till we see a photo of it, it might be savable, and you can just put it on a good gasser transmission, absolutely don't throw it away, it's worth money if it can be saved.

[millican]

I'll ask them to just put the old transmission in the back of the truck.