Engine runs fine but seems to seize after wot

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Im having trouble incorporating the 3 hr to normal restart thing into the above theory.
-I have seen it where a hot starter would not spin because the armature would magnetically stick to the field coil assy, due to excess clearance in the end bushing.Upon diss-assembly the drag marks could clearly be seen, both on the armature and on the coil. Just FYI.
 
On a friends engine had a spun main bearing that behaved like this. As soon an the engine reached temp it would shut down and start right back up after a long cool down. Oddly it produced no noise. He was also fond of no load nailing it to wot in the driveway.
 
mopar head said:
So, you set in your driveway and run it wide open?:shock:
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GeorgeH said:
On a friends engine had a spun main bearing that behaved like this. As soon an the engine reached temp it would shut down and start right back up after a long cool down. Oddly it produced no noise. He was also fond of no load nailing it to wot in the driveway.
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This is why I asked, with no reply, Bad on engine with no load:happy1:
 
After rereading the original post, and seeing "same thing happens in park", I came to the conclusion that my theory is likely way off; which is why I couldnt finish it.
-So, in park,all the circuit pressures in the trans are dumped by the manual valve, and even if the TC was all locked up, it would just become a very heavy flywheel.
-Assuming the engine really is seizing,that takes us back to; rings, pistons or main bearings. That means proving it by attempting to manually rotate the crankshaft, sparkplugs out, with a bar/socket on the dampner nut. If the bearings are seized the crank will not budge, but if its pistons it may move a tiny bit, back and forth. If its end gaps butted there may be a bit more crank-rock.
-In any case the only remedy seems to be engine tear-down.
-There is another scenario; hydro-loc.But the OP doesnt mention coolant loss, or coolant in oil,or steam clouds. And a 3 hr cool down period is likely not enough time for the coolant to drain away sufficiently enough to restart "like normal".
-So I guess I will have to concur with the previous poster(s) who said endgaps; even though the OP says he is tired of tearing the engine apart, as I cant imagine the damage not having been obvious enough to change the assembly specs. -Well, I guess there is one other possibility, however improbable; insufficient piston to head clearance.
-How-some-ever; in the event that the engine will turn over with the bar/socket test, proving that it is not really seized, then I would lean towards an electrical issue.
 
well, whatever it is, it probably won't happen too many more times before it's toast. Then it will be obvious.
 
When the rods blow out of the oil pan while revving the piss out of it in the drive way. I think you will get your answer!
 
AJ/FormS said:
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....
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Yes it goes from 5k to 0!in one second. It will not happen in part throttle. I want to try it with linkage discod but haven't yet. That's next step. It will crank but won't fire. Almost as if it he batt is real low. Other checks out will be done fri
 
-Ok,now we are getting somewhere.
-So heres the recap: Under Wot condition, in any gear including Park, at up to 5000rpm, engine QUITS to 0rpm in 1 second. Then attempting a restart, engine cranks very slowly, like battery is dying, but wont fire up. And it will do this also while cruising at say 30mph in Drive,going wot.Then 3 hours later cranks and fires up as normal.Oil pressure and coolant temps are normal.
-And it never; bogs, hesitates, sputters, or gives any sign of distress. It just stops running.
-That sound about right?
-And youve had the engine apart (several times?) looking for the problem and found nothing?And it still doesnt burn oil?
-Have you tried it with open headers or at least without mufflers, to prove its not the exhaust system? Does the engine seem to be making good torque under non-wot conditions.You know what, if somehow the exhaust backed up I suppose it could overheat the rings and/or pistons,maybe to the point of soft-seizing.I have seen that on small one-cylinder engines. But 5000 rpm to zero in 1 second.....I dunno.Seems like a longshot.
-Ok thats it for now. Ill keep watching.
 
So what did the trans fluid look like when you changed it? If it wasn't burned maybe there was a bunch of metal in the filter. If not, maybe you should look to the engine. Is it full with the proper oil? Pull the plug and check it for metal particles. Strain the oil and look for solids. You could have the trans and engine oil checked by a lab. That would give you an idea of the composition of the parts that are wearing.
 
back in the '90s when my duster had the 340 in it, it would lock up and stall at red lights (almost like letting the clutch out without releasing the brake. Hard to do with a 727 lol). Thought the tranny or converter was locking up, but it turned out to be the electronic ignition box.
 
No metal particles and oils are good. I will ck the box but I am still getting spark. I will also ck the start in neutral. Exhaust is free
 
Well, if you are sure the oils are free of contaminents, adjust the valves, and look to fuel supply, and ignition. I' d start with fuel 'cause for me it would be easier. I don' t know how high you are revving this engine, but if you could keep it below redline you could have a helper give it a quick shot of starting fluid when it tries to die. If it stays running you may have your answer.
 
Well now I can't get it to start at all but it cranks and has spark. Maybe the starter isn't turning fast enough?
 
Charge the battery first and then worry about the starter. You need to be certain it is getting enough fuel. By the way, the symptom you have could be indicative of an empty fuel tank.
 
How did you test for spark? Pulling a plug and watching the spark jump the plug gap is not nearly an adequate test; a weak spark can jump the spark plug gap in open air but not come close to jumping the gap in a compressed fuel/air mixture. In open air, the spark should jump a 1/4" gap or more. ANd I assume you are testing spark whiel cranking? Please confirm.

Starter not turning fast enough would be critical for a diesel but no so much for a gas engine; don't focus on that, IMO. Either the spark timing is going waaaaay off for some reason (but does not seem likely if the engine runs OK otherwise), or more likley you have a fuel problem: either flooded or no fuel.

So have you determined for sure that the engine is not physically seizing/locking up? The symptom descriptions seem to be all over the place, so it would be helpful to everyone to make sure what is going on; we can't be with you in the garage to see directly and pick up clues.
 
a couple of years back i had similar issues, MOPAR orange box was getting hot and would just stop working. also coil was weak.

went back to points and problem solved.
 
Yes the engine is physically not seized. I checked the spark in open air. What would u think the resistance should be on a accel super stick coil? It's getting fuel for sure. After trying to start for so long I checked the plugs and they are wet with fuel. Carb is good and so is timing chain set. Coolant is free from oil and visa versa. Battery is charged and still can't start. I think I am having to get a starter or at least have it tested.
 
If your valve lash is too tight an engine will start and run seemingly OK until the valves start to come up to operating temp and then then they tend to be open a tiny bit when they should be closed tight, the engine just slows down and dies. Will not restart until it cools down. I would try opening the lash up about .020 and try again. And yes it can happen with a hydraulic as well as solid cam. Good luck
 
Coil resistance is 1 ohm and sec is 12-15k. It's a super coil
 
It's not starting like it would if it had the valves opened
 
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