Engine runs fine but seems to seize after wot

[82CRUISER]

So I have checked everything I can think of except the trans. It all idles fine, has good fuel and oil press and timing is good. Coolant is also good. Shifts fine and can drive around but the second you accelerate bar or go wot the engine seems to seize. The same happens when it's in park in the driveway at wot. Won't restart after this. Let it sit for 3 hrs or so and it starts up as before. Any help would be awesome. I have been trying to do some research on line and on this site as well. The car is a 72 duster with 70 340 and a 904

 

[Dartswinger70]

I can tell you what happened to me. I had a four speed in my dart and similar instance where the car would run then seize sitting at Idle. Ended up being the input shaft bearing in the front of the trans. I think it is possible that something is seized in your trans. The only way to be sure is to heat it up until it seizes then remove your converter bolts and see if you can turn the engine with a breaker bar. remove your inspection cover while it is cold as it will be hot after you get it to seize. It sounds like work but you don't want to tear into your transmission unless you are positive that's where the problem is. Although if it is seized you wont be able to get the converter bolts out DOH!!!. Disregard...

 

[jimjimjimmy]

i have never heard of this problem before good luck getting to the bottom of it :happy1::happy1:

 

[moparlover]

the torque converter / trans need some love

you can try flush / fluid / then new filter in the trans first

after that gonna have to pull them

 

[82CRUISER]

Yea did a trans fluid change and filter. Thought it might have to do
With the throttle lever adjstement on the transmission. Anyone got a
TC they don't need

 

[magnumdart]

After it seizes, maybe you could just jack it up and try turning the rear wheels in neutral. If they don't turn or are difficult, probably a trans problem.

 

[B-onefan]

So I have checked everything I can think of except the trans. It all idles fine, has good fuel and oil press and timing is good. Coolant is also good. Shifts fine and can drive around but the second you accelerate bar or go wot the engine seems to seize. The same happens when it's in park in the driveway at wot. Won't restart after this. Let it sit for 3 hrs or so and it starts up as before. Any help would be awesome. I have been trying to do some research on line and on this site as well. The car is a 72 duster with 70 340 and a 904

What is your definition of "seize" ? You said it did this and then 3 hours later you started it right back up? I'm not following you here. You open the throttle and the motor just stops and will not even crank or turn over with the starter?

 

[jbc426]

...or by saying it seizes, do you mean it starts to crank and it stalls your starter due to too much initial timing?

After following the suggestions above and IF you find the motor turns over manually and is actually free to rotate, I would suspect if you retarded your initial timing you will eliminate the hot start problem. OR

You can also try to crank it with the ignition key in the off position, go under the hood and jumper the starter relay to see if it will spin over when there is no power to the ignition. If it spins with no ignition on, you may have a bad ground or too much initial advance.

Once in a while when my car is hot on a hot day, I have a switch to kill the ignition power until I get the engine spinning with the starter, then I flip on the power to the ignition and it fires right up. I have 12.8 to 1 compression, and my initial timing is set at about 22 degrees before TDC. This happens occasionally even with a strong mini starter and a big Oddessy capable of a 5000 amp dead-short with 0 gauge wire going directly to it and a 2 gauge ground cable going directly back to the battery. Plus my block is grounded to the car, as is the battery.

 

[mguner]

Maybe it's not actually seizing but losing ground to the electrical system when the engine torques?

 

[82CRUISER]

Thanks for the info. I will try all ideas. I also think the starter is getting to hot
From headers but still doesn't explain the engine cutting off

 

[TrailBeast]

Thanks for the info. I will try all ideas. I also think the starter is getting to hot From headers but still doesn't explain the engine cutting off

Don't mean to offend or anything, but "cutting off" isn't much of a description to go on.

Could be anything from the fuel pump to the ring and pinion.

 

[82CRUISER]

Bone fan it is actually stopping and seems to seize and not restart. I hope it's
Trans related. Tired of pulling the motor apart

 

[82CRUISER]

Fuel pump is fine. I can turn the key to on and it fills the bowls and squirts
When I press the acc pump. Think of it this way. Let's say u have a manual trans
And u start your car and butt up the front bumper to a building. Now put it in 3rd gear, hold the brakes and keep parking brake on and me out the clutch. What happens? It dies instantly. ( cue smart comments) now obviously no one would do this.
Keep applying the brakes with the vehicle in gear try to start it. Nothing
Happens. Now have some friends help u push it away from said building. Put it in neutral
And start it 3 hrs later. That is the indications the car is having

 

[1969383S]

I can tell you what happened to me. I had a four speed in my dart and similar instance where the car would run then seize sitting at Idle. Ended up being the input shaft bearing in the front of the trans. I think it is possible that something is seized in your trans. The only way to be sure is to heat it up until it seizes then remove your converter bolts and see if you can turn the engine with a breaker bar. remove your inspection cover while it is cold as it will be hot after you get it to seize. It sounds like work but you don't want to tear into your transmission unless you are positive that's where the problem is. Although if it is seized you wont be able to get the converter bolts out DOH!!!. Disregard...

Don't overlook the pilot bushing....

My Cummins Diesel locked up when the torrington pilot bearing failed. Hard to believe a little needle bearing could lock up a tourqe monster like that but it did.!!

 

[TrailBeast]

Fuel pump is fine. I can turn the key to on and it fills the bowls and squirts When I press the acc pump. Think of it this way. Let's say u have a manual trans And u start your car and butt up the front bumper to a building. Now put it in 3rd gear, hold the brakes and keep parking brake on and me out the clutch. What happens? It dies instantly. ( cue smart comments) now obviously no one would do this. Keep applying the brakes with the vehicle in gear try to start it. Nothing Happens. Now have some friends help u push it away from said building. Put it in neutral And start it 3 hrs later. That is the indications the car is having

Nothing happens? or the car jumps a little but the engine won't turn over?
It does sound like a bad converter from that description.

Excellent description.

 

[moparlover]

also could be gas lines clogged now that i think of it... tank is full of rust and stuff

clotting of the arteries

 

[TrailBeast]

also could be gas lines clogged now that i think of it... tank is full of rust and stuff clotting of the arteries

From that last explanation of symtoms I got the impression it is definatly a drivetrain problem.

But this statement is a little confusing because it shouldn't be starting in gear anyway, but it seems as though he is describing a froze up converter.

"Let's say u have a manual trans And u start your car and butt up the front bumper to a building. Now put it in 3rd gear, hold the brakes and keep parking brake on and me out the clutch. What happens? It dies instantly. ( cue smart comments) now obviously no one would do this. Keep applying the brakes with the vehicle in gear try to start it. Nothing Happens. Now have some friends help u push it away from said building. Put it in neutral And start it 3 hrs later."

 

[mopar head]

The same happens when it's in park in the driveway at wot.

So, you set in your driveway and run it wide open?:shock:

 

[BigBlockMopar]

So what are your piston ring-gaps set at?

 

[Oklacarcollecto]

Don't overlook the pilot bushing.... My Cummins Diesel locked up when the torrington pilot bearing failed. Hard to believe a little needle bearing could lock up a tourqe monster like that but it did.!!

A 904 doesn't use a pilot bushing.

So what are your piston ring-gaps set at?

You might be on to something there.

 

[1969383S]

A 904 doesn't use a pilot bushing.



You might be on to something there.

No doubt.. About the 904..

Thought I read clutch somewhere in these posts!!!!

 

[82CRUISER]

Ring gaps are good. Tried to start it today and battery was flat. Will try again tomo.

 

[BigBlockMopar]

Awesome info.

 

[AJ/FormS]

When you say seizes:
-Is it rpm related or throttle position related? See, you can go wot at any rpm, right? And are you saying the engine goes from 5000rpm to zero rpm in like 1 second or 5 or what? And if its rpm related, can you get it to seize at part throttle? Does the engine bog or hesitate first or just flat quit, like you shut it off? Is there any sign of missfire or backfire?
-When you say it wont restart; does that mean:A) it wont crank? Or B) cranks but wont fire? If A) it wont crank, have you tried to manually turn the engine over? If yes you tried but it wouldnt move, then remove all sparkplugs and retry. If it still wont move, well then get the rear wheels off the ground, put the gear selector into neutral and retry.If it still wont turn over, then it really is seized.
-Assuming it "really is seized",you said the oil pressure is "good", so lets assume the bearings are all good. Inside the engine the only thing left, powerful enough to stall the motor at wot, is the pistons and rings. Since you said it runs fine and didnt mention burns oil, lets also assume the rings are "good". Well that just leaves pistons. However after several seizures, there would have been enough metal transfer to tear up the rings and you would have a smoking engine, which you again didnt mention. So, conclusion is; its not the engine.
-Moving along; Some have indicated a possible bad convertor. Well lets think about that.You said it "runs and idles and drives fine".And it happens in park also. Well if the parts inside the convertor were to seize, I cant imagine that you wouldnt have mentioned how crappy the acceleration was, or something about it stalling when you put it into gear.So lets move on.Lets go to the hub and pump.If the hub were to seize in the front bushing, it would just tear it out.If the pump were to seize it wouldnt stall the motor at 5000rpm. So moving along;The only other thing indirectly connected to the the crankshaft is the input shaft to the rear drum(forward clutch). Lets see, how could that seize at 5000rpm and stall the motor? Im not getting a picture.....
-Heres what I am picturing.Going back to it only happens at WOT.Again, assuming, your KD linkage is functioning correctly, lets think about whats happening. Your cruising along in Drive and you mash it. The KD linkage calls for a downshift. Depending on your roadspeed, the trans will want to go to 2nd or 1st, right? But its still in Drive. What if the trans is finding two gears at once? .......Instant stall.How can this happen? I dont know, but we will have to prove it.Or disprove it. I would be tempted to disconnect the KD linkage and try it.This will prevent a WOT downshift command. If the problem goes away, now youve learned something.If it persists, the theory could still be right; it just not KD related. It could be a ValveBody issue.
-Now on to the restart.If the engine stalled due to a tranny locked up, at wot, chances are very good that it is flooded.And, as soon as the pressures in the tranny leaked down enough to free the clutches( a few seconds), it should at least crank.Unless it hydrolocked.
-Now getting back to tranny locked-up.In a mopar tranny there are 2 bands and 2 clutches. On a stock VB when any forward gear is selected,the forward(called rear clutch) clutch is engaged.For manual low the rear band is energized as well.For 2nd the rear band is released and the front band is energized, as well. For Drive the front band is released and the Hi-drum (called front) clutch is engaged,as well. When reverse is selected,the forward clutch is released, the rear band is applied and the hi-drum is engaged. Its easy for me to imagine a failure in the hydraulic circuits causing a two-gear lock-up.Esp the 3-2 downshift circuit, which is hi not releasing while front band is applying.Or 3-1 downshift, which is hi not releasing while rear band is applying.
-Ok my head hurts....

 

[Lonewolf3165]

Is it a lock-up transmission(lock-up converter)? Perhaps a malfunction causing the converter to lock up & then after time the pressure bleeds out of it & it releases.

My 1st thought was ring end gap, but you said you have checked that.