3FE Won't Run After Clunk - Realtime (1 Viewer)

[CJF]

This is intriguing; I wish I was nearby so I could check it out in person.

Seems like the next step would be to see if the starter is in fact turning the flywheel. Flywheel should be visible through the inspection plate near the back of the motor?

Curtis

 

[jonheld]

How can this be?
How can the starter be spinning the flywheel and not have the crank pulley turn?

I'm not sure, but that may be a problem...

I think you are on the right track by seeking local help at this point.

Perhaps it's time for a bit more history on this motor. Something a bit more detailed than, "I was driving home and..."

 

[TrustyToyota]

This is intriguing; I wish I was nearby so I could check it out in person.

Seems like the next step would be to see if the starter is in fact turning the flywheel. Flywheel should be visible through the inspection plate near the back of the motor?

Curtis

This was the next step to see what the starter is turning. If the flywheel is turning, I can only think that leaves the connection to the crank or the crank itself to be broken. Both not good things.

 

[jonheld]

If the flywheel is turning I would drop the oil pan and pick up all the parts that come out.

The flywheel (driveplate) is bolted to the crank with 6 bolts. The crank is supported with 4 main bearings. I suppose the crank can split in half and still be supported by the mains. If it was a clean break then the front half of the motor wouldn't turn but the rear half would still crank.

FWIW, I have never heard of a crank failure in a 3FE. Anything is possible...

You didn't notice any pistons sticking out anywhere did ya?

If the driveplate is in fact being spun by the starter, drop the oil pan immediately and all will be revealed.

 

[TrustyToyota]

So with the holiday and two jobs, I finally got a chance to get under the truck to take a look at the inspection plate to check the flywheel. The flywheel IS turning when the truck is turned over. The crankshaft pulley is not turning. The inspection plate was not installed when I got under there, so someone has been into this thing before me. I guess that's not too big of a surprise given the age of the truck.

With my research it seems to me that there are 3 options for failure here:

1. The connection between the flywheel and the crank is busted. This doesn't seem likely, but neither does a busted crank.

2. The connection between the crank pulley and the crank is busted. I don't understand this connection so I don't know if this could even be a possibility. If I try to turn the belts by hand, they don't move, or even budge for that matter. That pulley is locked onto something if it isn't the crank.

3. The crank is busted. From what I've read and heard, if this was the failure, I would have known. They don't break easy.

All three options seem highly unlikely to me.

My next move is to try to get this thing off the Minneapolis streets to a driveway where I can drop the oil pan and see what is going on down there. Where it sits now, dropping the pan is not an option. I need to find a trailer/dolly to move the thing so I can investigate. My first reaction is that if any of the 3 options are the true mode of failure, the truck has met its end. What do you all think?

 

[jonheld]

There are 6 small bolts that hold the outer pulley onto the crank pulley. The crank pulley is bolted to the end of the crank with a 46mm nut. Pretty hard to miss that one.

As far as what comes next, I would make CERTAIN that the crank pulley is seated correctly on the crank and that the nut is in fact on there. If that looks good, have someone crank the motor while you are staring at the crankshaft end. I would look with a careful eyeball at the center of the shaft and see if it spins.

If no spinny, then drop the pan and see what you find.

If it's bad, what comes next will differ depending on many factors. No one can tell you what to do. Diagnosis is first. What is damaged and more importantly what is NOT damaged. Your options are repair, replace, or start over.

 

[Lka1988]

So with the holiday and two jobs, I finally got a chance to get under the truck to take a look at the inspection plate to check the flywheel. The flywheel IS turning when the truck is turned over. The crankshaft pulley is not turning. The inspection plate was not installed when I got under there, so someone has been into this thing before me. I guess that's not too big of a surprise given the age of the truck.

With my research it seems to me that there are 3 options for failure here:

1. The connection between the flywheel and the crank is busted. This doesn't seem likely, but neither does a busted crank.

2. The connection between the crank pulley and the crank is busted. I don't understand this connection so I don't know if this could even be a possibility. If I try to turn the belts by hand, they don't move, or even budge for that matter. That pulley is locked onto something if it isn't the crank.

3. The crank is busted. From what I've read and heard, if this was the failure, I would have known. They don't break easy.

All three options seem highly unlikely to me.

My next move is to try to get this thing off the Minneapolis streets to a driveway where I can drop the oil pan and see what is going on down there. Where it sits now, dropping the pan is not an option. I need to find a trailer/dolly to move the thing so I can investigate. My first reaction is that if any of the 3 options are the true mode of failure, the truck has met its end. What do you all think?

If it comes to the worst, build a 2FE. All it needs is the 3FE head

 

[Lka1988]

Open the oil cap so you can see the valve train. Have a buddy crank the motor and see if there is any movement.

 

[RockDoc]

Open the oil cap so you can see the valve train. Have a buddy crank the motor and see if there is any movement.

Or distributor with the cap off?

 

[Lka1988]

My method is easier

But seriously, both are easier than dropping the oil pan and should give good clues to what's going on.

 

[RockDoc]

My method is easier

I'll concede that.

 

[surfersti]

timing chain?

 

[CJF]

timing chain?

1) No timing chain on a 91-92: Geared timing with a camshaft for the valves down by the crankshaft. (I.e., a "pushrod" motor.)

2) Even if that were the problem, front crankshaft pulley and associated belts would still turn.

Welcome ,

Curtis

 

[voorland80]

as a fellow 3fe driver, the suspense is killin' me. have you found out anything else? I wish I was closer.

 

[TrickyT]

Indeed, this sounds like an unusual 3FE problem. If you've still got all the spark plugs out, then if you put a finger loosely over each plug hole while you crank the engine you'll feel and hear a blast of air ejected on each compression stroke. Obviously all six cylinders should do this and indicates the pistons are moving up and down. This together with the visual valve train movement as Lka1988 suggests will tell you if the basic mechanicals of the engine are okay without the need to drop the oil pan (a sometimes difficult task on the 3FE). The front crank pulley is keyed to the crankshaft and held on with a 46mm nut that is torqued to something like 250 ft-lbs (grunt). Even if that was spinning on the crankshaft you'd still get spark and could start the engine because the distributor is driven by the camshaft which is geared to the crankshaft. If the pistons move but the valve train doesn't then one of the keys on either the cam gear of the crank gear has sheared, or the fiber cam gear has failed. To know more about that, you'd need to pull off the timing gear cover - not a job to do on the street during the MN winter. At any rate, you can easily do the above simple tests with the vehicle in its current location. Post up your test results so we can all suggest what to do next.

 

[TrustyToyota]

Sorry for not updating sooner!

Things have been chaos lately, so unfortunately this rig doesn't get much of my time. I'm going to try and pull plugs to do the "finger compression" test this evening. I don't know this for sure, but I don't think the distributor is spinning. I may pull the cap on that and give it a crank to see if that is turning at all.

Another question. When I was troubleshooting spark before, I could have sworn I was getting a strong fuel smell. If the crank isn't spinning, would the fuel pump still push fuel into the cylinders? It doesn't really matter at this point, but I just remembered that piece.

I'm going to try and see if the valve train is moving at all too by pulling the oil cap.

If that crank pulley is keyed to the crank (thanks TrickyT) then at least that portion of the crank is not spinning. The large nut on the front of the pulley is still there and is tight.

 

[TrickyT]

I'd say if you were smelling fuel, and it was being pumped out of the cylinders, then the pistons are moving. The finger compression test will help verify this.

Ideally you should check if both the valve train is moving AND the distributor is spinning. If the valve train moves but the distributor does not, then either the pin that holds the drive gear on the bottom of the distributor has sheared (rare, but not unheard of) or the drive gear on the camshaft, which is pressed on, has loosened and is spinning around on the camshaft (theoretically possible, but I've never heard of it actually happening).

Don't know what to say about the crank pulley. The key could have sheared, and so the pulley is now spinning on crankshaft. But I would think the big nut would also have to be loose for this to happen and you'd still see the nut turn when you cranked the engine. This symptom seems to argue for a more serious problem with your motor, like a busted crankshaft. The tests above are designed to help sort this all out.

 

[TrustyToyota]

The Cruiser Gods are not on my side with this one...

Hey everyone.

I finally got a chance to do some troubleshooting on the '92.

I first pulled the oil cap to see if anything was moving. It was not.

I then pulled the distributor cap to see if it was spinning. It was not.

I then pulled the plugs and did the "finger compression" test:
6-4: compression
3 and up: no compression

First off, my initial reaction is broken crank, but please correct me if that is off line.

Now I guess I will clear up some of the questions that were asked by everyone and myself:

Please tell me how it is possible that you can mistake the sound of the engine turning over as compared to just the starter turning.

It is possible because half of the engine is apparently spinning while the other half is not. I don't feel like as big an idiot anymore. The starter is turning SOME of the motor.

How can the starter be spinning the flywheel and not have the crank pulley turn?

Apparently the crank CAN break without too much of a fight and the starter will turn the flywheel and part of the crank; but not the part that attaches to the crank pulley.

Another question. When I was troubleshooting spark before, I could have sworn I was getting a strong fuel smell. If the crank isn't spinning, would the fuel pump still push fuel into the cylinders?

When I had pulled a plug before to test for spark, I pulled the number 5 cylinder plug since it was easy to get to. Since that cylinder was still moving, I think it was still getting fuel, hence the smell of fuel.

Now my new, major question is: Why did the crank break?

As I had said before, I was not driving the truck hard when it happened, I was merely accelerating slowly from a corner. I don't know, but I would think something in the front end of the engine locked up and stopped the crank quickly, but the back of the engine and flywheel didn't have the same plan. This also brings me back to the fact that I cannot turn the belts on the front of the engine by hand with plugs out. Something in there has got to be holding things up.

Well, I can't say this is the first time its ever happened to a 3FE, but its the only one I have seen on MUD.

And you can trust me... I searched.

 

[RockDoc]

Wow!!!

I think you'll have to pull at least the head and oil pan to find out for sure what happened. This is the first I've heard of a LandCruiser with a multiple displacement system.

 

[Cruiserdrew]

Subscribing.

If you have compression at the rear and not at all in the front, it is logical to assume the crank is broken, and something in front of the break is seized.

Pull the oil pan as was suggested, and watch the crank when an assistant cranks the motor briefly. Wear eye and face protection and keep a bit of distance.