can the torque converter on my 1997 Chevrolet Blazer 4.3 litre vortec 4 wheel drive be locked up not allowing the motor to turn with the starter or manually with a breaker bar and socket on the crank

The torque converter would not stop the engine from turning over. When a torque converter locks up it is usually just stuck so the trany runs in one gear. Easiest way to start determining if the motor is locked up is to pull all the spark plugs so there would be no compression. Also take the starter off and inspect it, maybe the starter dive is locked into the ring gear. Once the starter is off, then try and rotate the engine at the ring gear with a pry bar. Look to see if all the torque converter bolts are in place also. If I can think of anything else I'll let you know, just give a response so I can find this post again.

Thanks for your response. I was able to get out and work on the blazer today. I removed the starter and bench tested it and it seems fine. I didn't expect to find anything wrong with it anyways. I went ahead and removed 5 of the 6 spark plugs (6th one was behind steering column and couldn't even get a socket on it, but thought 5 should be enough to enable me to hand crank the engine). There is no inspection plate to allow access to the flywheel and torque converter bolts ( to my surprise ). I'm baffled! I've never seen a rear wheel drive where the oil pan comes all the way down to where the bottom of the bell housing is and there is no access to the torque converter or flywheel. Am I missing something? The how to and help websites that I have visited (and even watched a video) say there should be a removable inspection plate. Instead of using a pry bar on the flywheel teeth to try and turn the engine I took a 5/8 deepwell socket and a long 1/2 inch drive ratchet and tried turning the engine with the bolt on the front of the crankshaft. Even with 5 of the spark plugs removed I couldn't budge it. If it is the motor locked up, what would cause a motor thats running good with good oil pressure and temperature to just die out of the blue? And would it have started back up and ran okay until I started driving it again and then "out of the blue" die again, never to turn over again? There were no funny noises or anything. Help!!!

I'll have to do some checking myself. This has my interest. Like how would you secure the torque converter when installing an engine? There has to be access. And it certainly doesn't make any sense for this to just stop turning over without any noise. I don't see at this point that the problem is with the engine. It may be behind the engine, torque converter & transmission, I don't know but want to figure this out.

Also use a 5/8 off set wrench to get that last spark plug out.

And did you notice any damage to the spark plugs? Get that last one out to look at it also.

What are you finding on this?

Just got a chance to see your replies. Thanks again for your help. To answer a couple of your questions, no there was no damage to the spark plugs in fact they looked brand new but I have yet to get the last one out. Also I looked online and found instructions for removing the torque converter bolts. You have to access each one thru the hole where the starter fits in, rotating the engine to get to each one. Not very helpful when you can't rotate it. What checking I have done has gotten varied answers. I have been told that it couldn't possibly be the torque converter and I have been told that yes , that locking torque converter could very well stop the motor from turning. In fact I never suspected it until I started having people tell me about it. I did try to think it thru on my own and decided that if the torque converter was locked and the transmission was stopped it could hold the motor in place, so I took it out of gear yesterday and pushed the vehicle back and forth in the driveway while someone watched the pulley on the crank to see if it turned. It did not, so I'm back to thinking that the engine is probably the culprit. I would still welcome any info. that you might find out. Thanks again.

You may want to start by pulling the distributor to see if the gear is intact. Then the timing chain cover, or pull the trany, I bet you'll be pulling this thing apart to find the problem.

Have a 98 Blazer the engine locked up wouldn't turn over either. It turned out to be hydrolocked because of fuel injector stuck open and filled my number 4 cylinder completely with gas. Change the Spider injector new plugs truck runs perfect again. When I went to change the oil found about a gallon of gas had mixed in made it past the piston.

Even the garage missed it they said it was trashed offered to buy the truck off of me. Best thing I ever did was have it towed home and pulled all the spark plugs. Come to find out those spider injectors GM put in those trucks are garbage. The new injectors are actually an upgrade and truck will run better than it ever had before.