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Q: Transmission locked

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Removed engine while waiting for replacement I was pushing truck in and out of shop until eventually one day trans locked up. I removed drive shaft to push truck in and out of shop. I have received new engine and installed it but need to line up flywheel bolts but need to unlock trans.
My car has an automatic transmission.

For your GMC C1500, the transmission input shaft should still turn by spinning the torque converter. If you cannot turn the converter, then you are binding the engine and transmission together.

What may have happened is a torque converter that may have slipped part way out of the transmission and started binding the front pump. You will need to remove the engine out of the way and remove the torque converter from the transmission to see if any damage was done to the transmission front pump or input shaft.

While supporting the front of the converter insert into the transmission by spinning it and pushing it into the transmission at the same time until it is fully seated into the transmission, and then you should be able to turn the front transmission pump by turning the converter. Install the engine and hook it up as normal. If you need help with any of this, a certified technician from YourMechanic can come check your car and advise you with this installation.

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