First off, the truck is a 98, 2WD, V6, with a 4R70W automatic and overdrive started slipping a couple weeks ago. We got a new (used) junkyard tranny to swap in so we can sell the truck.

I got the new tranny in and bolted up to the motor and crossmember and got the torque converter and flexplate lined up with no problems. The problem I did notice is when i tried to rotate the motor to tighten the 4 flexplate/torque converter nuts i was getting a lot of resistance, i mean i used a breaker bar and my body weight with no luck. i loosened all the bellhousing/motor bolts and backed the tranny off about 1/4" to 1/2". With the transmission loose i was able to rotate the motor to tighten the fp/tc nuts and then i tightened the tranny/motor bolts back. With everything all back together i tried rotating again w/ the breaker bar and still had some resistance, but the motor would barely rotate. Then i tried starting the truck and it had a very tough time turning over and when it did start it promptly died. i stopped at this point to contemplate the situation.

I have a couple of ideas:
1. the torque convert is not completely set on the transmission input shaft splines putting a lot of pressure on the motors rotating assembly
2. maybe we got a bogus tranny that's not allowing the motor to rotate (but it rotated fine when i loosened the tranny)

Has anyone come across a situation like this?

Any thoughts would be greatly appreciated.

Thanks,
Avery

 

That's what happened.

That is not likely, but not impossible. Pull the trans out and see if you can rotate the torque converter. To fix #1 above you need to remove the trans anyway.

This actually happens quite often.

Once the trans is out remove the torque converter. See if the end that goes into the trans shows any damage, or if the shaft that goes into the torque converter shows any damage. If so, rebuild this trans or replace it. Running the engine with the torque converter bound up can destroy a lot of parts.

If everything looks good, stand the trans on end so that the bellhousing is up. Install the torque converter and rotate. You'll feel it drop down each time a spline engages. There are three splines that need to engage. Keep rotating until you feel all three engagements. If the torque converter is fully seated the front of the converter will be below the front face of the bellhousing. The be careful so that the converter doesn't slip back out while you are installing the trans!

 

casey is right, this could be bad.

Usually this is from the torque converter not being seated all the way. Unfortunately this usually also ends up destroying the transmission and possibly the converter if the vehicle is started that way.

Not good.

The way to check this is to keep checking the converter during installation. If the trans binds up at all or doesn't want to go in then make sure the converter can move and ALWAYS check this before installing the converter bolts. If the converter has free movement inside the bolt holes it will clang side to side with very little effort. You just stick your thumb up in the round hole on the bellhousing and move it side to side with your thumb.

If it isn't moving freely then take it all back off and reseat the converter.

Also like he said, this happens a lot. I hear it all the time and hate when I hear that people started the vehicle. It almost never turns out good for them after that.

Sorry to have to tell you this.

Darrin