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truck locked up tight

Posted by timlynn (My Page) on
Thu, Jun 4, 09 at 15:31

350 in 96 1500 locked up tight. Just driving down the road and it stopped. I tried turning it over and it moved the pulleys maybe a 1/4 inch and just stopped. I replaced starter cause thought it was bad. Makes the clang as it engages the teeth on the flywheel and nothing. I tried to turn the crank shaft with socket and it is froze tight.
I never had a chevy engine do this. I have spun lots of bearings in them and thru rods thru the oil pan but never locked one up from normal driving before. There was no sign of troubles from this engine at all. Now I am thinking I might of dropped a valve. But I have never done that before on my older chevys. After I pull the covers and check, Has anyone else had this problem and what else should I check for after that? Pull the oil pan and start loosening the rod and mains one at a time till it turns would be my only other try after the valve check.


Follow-Up Postings:

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RE: truck locked up tight

If you can turn your crank back and forth about 1/4 inch either way usually means the crank is free but the pistons are seized in the block. The engine will definately have to be taken apart. Engines are funny people. One day they love you and the next day they leave you.


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RE: truck locked up tight

HOLD UP!! Don't get too anzy and start taking everything apart. Using a large socket and torque wrench try rotating the engine the opposite direction!! This can un lock the probable cause which could be a timing chain that broke in at obe of the pinned connectors causing the chain to wrap around and JAM the engine. Start out by removing the timing chain cover instead. This is why i am telling you to turn the engine in the opposite direction, because this would reverse the condition that caused the lockup.

Another thing to look for..Take a large screwdriver and underneath the truck turn the flywheel by turing one tooth at a time. Many times vehicles without dust covers can get an iten stuck in the flywheel area. But anytime an engine runs okay without knocks or clanks and locks..generally it will be something more external such as timing chain wrap around from a PIN coming loose in the chain assembly.


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RE: truck locked up tight

If the timing chain broke or jumped a bunch of teeth, the pistons may have hit the valves - Ugh - unless the 360 is a free turning engine.

I don't have information about your engine. If it has a distributor, remove the cap and rock the crank back and forth. The rotor should move, maybe with some play. If the rotor does not move, this is a clue.

If your engine does not have a distributor, remove a valve cover and rock the crank back and forth. Do any of the rocker arms move?

Let us know what your find. You've got us curious.


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RE: truck locked up tight

If he takes a valve cover off of the engine, he needs to observe as to whether one of the retainers came loose from a valve top and dropped a valve in a cylinder, causing a totally loose rocker arm as well.

As far as checking for movement of the distributer shaft under the cap, that is wasted time simply because it won't move if the crank assembly is "LOCKED", nor would that relate to the issue at hand of assembly lockup.

And if a timing chain breaks or skips that CAN NOT MAKE A PISTON TOP TOUCH A VALVE,...because crank and rod assembly does not change it's stroke height because of timing or chains or cams, as it is a pre assembled fixed rotating assembly. The only way a piston can protude in bore assembly height is to disengage from crankshaft at insert and bearing cap.


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RE: truck locked up tight

Ok guys. Thanks for the replies. I haven't had time to do anything to figure out the problems. I am going to hit a few tries as rotate the crank with a large socket to see if it might be the chain that broke or a dropped valve. Take the plugs out to reduce some pressure. The valve covers first because they are the easiest to do. That is if the engine does turn with breaker bar. I might have to make a custom socket with arms on it to catch on couple of the pully bolts to keep from loosening the balancer bolt as I try to free it backwards. I will get back to you all in a few hrs. Thanks for the replies all.


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RE: truck locked up tight

Not looking good here. I have to pre fab a socket with arms to catch a few pully bolts now. If it doesn't turn then I would have to say a piston seized in the block. But it doesn't make sense though. 30mph and it stalls then I start it again and pull off road and it stalls and locks up.But I have to wait till tomorro to fab my socket. I could pull the balancer and put a rag around the crank and then use a pipe wrench on it. I don't have a special socket with groove for key way. I think I will just pull the balancer and use pipe wrench. It would be stronger and I could use a pipe for an extender and try to free that puppy up. See what gives.


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RE: truck locked up tight

Before you go and remove your balancer, have you tries removing your dust cover and prying with a screw driver at the edge of the bell housing and flywheel teeth??

And yes, taking the valve covers off is a time saver because if you dropped a valve you are going to have a rocker arm with 2 inches of play for sure.

For an egine to run smoothly without a metalic noice is strange, but could be a valve dropped and inserted at a cylinder angle and locked everything.


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RE: truck locked up tight

Let's ease up a bit. Remove the spark plugs to make the engine easier to turn (under normal circumstances). Apply a socket and handle to the damper/pulley nut and try rocking the crank. Under normal circumstances, the crank is fairly easy to turn and can be turned either way without loosening the pulley nut. If you have to apply very much force, its jammed and forcing it will do no good.

There is one more item to check - the starter. It is rare and happened on cars made from 1930 through 1953. I haven't heard of jammed starters in recent times. The starter can engage the flywheel, then go bad and jam. This locks the engine until the starter is removed. On old cars, sometimes we could unlock a starter by turning the engine backwards. (It seemed to happen on Saturday night dates.) This only works with a manual transmission. Have an assitant sit in the driver's seat, put the engine in a forward gear either second or high, then while the assistant holds the clutch in, the second person begins to rock the car or roll it backwards. The assistant lets the clutch out as the car moves backward. This will bump the engine backwards (without any tools). Often, this technique would release a jammed starter.

Unfortunately, I have little hope that it is a jammed starter. I see in a later post you stated that the engine stopped while going 30 mph, and was restarted and the engine quit again.

Whatever you do, do not remove the damper/pulley and apply a pipe wrench to the end of the crank. This is a press fit surface and is precision machined to a tolerance less than .001 inch. Yeh, the pulley/damper is hard to get off the crank. It is keyed and pressed on. You'll need a puller to get it off, and will likely have to remove the radiator to get access and to prevent dings in the radiator. Let's reserve taking off the pulley until later. You only need to remove it if you are removing the timing chain cover. If you can not rotate the crank using nomimal force with the spark plugs removed, there is a serious jam inside and forcing it will do more damage.


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RE: truck locked up tight

As always test don't guess. An engine could be locked up simply because of an internal failure. But it really doesn't happen just out of the blue. There are always signs, it comes down to the driver noticing them. When one of these engines appear to lock up suddenly, it could actually be a transmission problem, or something as simple as the alternator. To find out, you'll have to first remove the belt and now see if the engine turns. Attempt to unbolt the flywheel from the torque converter (assuming this is an automatic, I didn't see where this was specified). Unbolting the flywheel can be quite difficult if the crankshaft in the engine wont turn. This only has a 7/16" front crank bolt, so be careful about how much torque you attempt to use to turn the crank by hand. If this isn't turning at 50-70 ft/lbs something is causing it to not turn. Its quite likely you may need to drop the pan, and pull main and rod bearing caps one at a time to see if you can then get the crankshaft to turn. You might even need to do this in order to unbolt the flywheel from the converter. Do not attempt to turn the crank with a pipe wrench with the damper removed. That would at the least be a waste of time, you can turn the engine with just the regular crank bolt, again watch how much torque you apply. At the worst, you could do more damage to the crankshaft, and/or the pulley key-way. Forcing the engine to turn now will not allow you to run it again without a repair, so don't damage anything else trying.


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RE: truck locked up tight

you have spun rod bearings and broke rods before? whew, you must be hard on motors. or maybe you tow a lot or maybe you don't maintain your vehicles? don't want to get you mad but very few people blow motors. yes some do fail out of the blue but its not common. they do sell crank adapters to turn over motors. gotta take of the balancer to fit it on though. a 96 chevy 350 is pretty cheap used. not hard to find one.


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RE: truck locked up tight

Take the serpentine belt off and try to see if it spins. You may have an alternator locked up.


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RE: truck locked up tight

not to be rude but there is no way in hell you have an
alternator lock up. Water pump lock up, power steering pump
lock up, or A.C. compressor lock up or all of the above at the same time. That will never stop and engine from running. It will burn the belt off first. My money is on Joe MN. You've spun a rod bearing. Bottom line. Why try to get it to turn. The motor is done. It has to come apart and be rebuilt or replaced.


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RE: truck locked up tight,, piston touching a valve.

One thing i forgot and no offence but i don't think Earl53
has much experiance in engine failures. You have no idea how many engines i've seen when the piston kisses a valve.
I can't count how many push rods i've bent on my 312 on an
over rev when the piston kissed a valve. not that common on
hydrolic lifters but normal on solid lifters. They call it
an interference engine. Timing belts are non interference
engines because the belt will break or jump as you drive.
Normal. Ever seen a hydrolic lifter " pump up " and punch a valve through the piston top ? Almost normal on the old
318 dodge. 390 had the same problem. When a rod bearing spins the connecting rod will also push the piston up higher than deck hight but if the valve timing is ok there will be no valve kiss. ( almost no valve kiss )if operated
at normal road speed. Please disregaurd this post if found
offensive.


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RE: truck locked up tight

a broken valve with piston bits in 1 cyl could make the motor turn over not well at all. could you pull some plugs and look for debris on the plug tips? maybe no oil pressure seized some bearings. crank, rod, or cam bearing?


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RE: truck locked up tight

kalinin.

An alternator can lock up and cause a no-start, no-crank, can't turn the crankshaft by hand on these! The 4.3l V-6's are known to do it as well. A good belt, with a good tensioner really grabs the pulley firmly.


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RE: truck locked up tight

I might partially agree with that. Usually a bearing seizes
as it stops moving and will not turn again on the next start. Funny thing you mentioned a 4.3. My brother had one
in his shop last month. Alt seized but didn't stop the motor. The belt caught fire and seriously damaged the under hood and related parts.They wrote the car off.


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RE: truck locked up tight

The reason I mentioned the alternator possibly being locked up is because that is what happened to me on my 1990 Silverado with a 350. The engine just stopped dead at a stop light. The starter would not turn the engine over at all, only engage and stop. I normally would not have thought that the alternator would prevent the engine from turning, until it happened to me. Sometimes we get lucky and it is the simple things we overlook.


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RE: truck locked up tight

LOL..I suspected this topic was made by someone, then either site administrators followed it up to make it appear somewhat real to the NOVICE or maybe a group of people "bored wanna be guys whom know one another" decided to play on a forum.

Other than my own replies..the replies are NONSENSE and FICTICIOUS. You sillies that are arguing and "catching and throwing" do not even know if the distributor is on the front or back of the 350.

As i said before..you clowns do not know who you're responding to with your nonsense.


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RE: truck locked up tight

Earl.

Fill out your member page so we get to know who you are, and see what your experience is. To get to my page simply click on the link next to my name. Now granted mine does need updated, I think its been four or five years since that one was written. But as an ASE CMAT, L1, A9 with over 32 years experience as a full time technician, who averages fifty cars a week inside my own shop, who owns fourteen FACTORY level, or otherwise known as O.E. scan tools, attends over 100 hours classroom training each year, and as an instructor, delivers approx 400 hours of continuing education classes for professional technicians all over the eastern United States I'm pretty sure that I don't have to tolerate statements like the ones you have made in this forum.

In your own words, "You don't know who you are talking to", but now you should have an idea. If those (my) VERIFIABLE credentials aren't enough, I'll get a few people from around the country to chime in.


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RE: truck locked up tight

Come on, Earl53, Lighten up. You have been attacking some of the best responders on this forum. It makes me wonder why?


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