Bad vibration?

Whats up any help would be appriciated here. I have a 89 jimmy 4.3 4x4 with 176,000 miles when you are driving around town it runs great no problem but when you get it out on the highway or rev the engine up above 3,000 rpm it vibrates really bad. It is just the motor to not the drive line if ya put it in neutral and rev it it does the same harmonic vibration really bad, the faster the motor goes the worse it get. Also around town the temp is fine bout 190 but on the highway runs about 220 or 230, dont know if that makes a diff or nor. Thanks for help

This one could be a few things. Loose torque convorter bolts, harmonic balancer going bad up front. If thats an original balancer, it could very well be it. It could be a transmission problem, a loose/worn torque convertor bushing. Either way this problem can be hard on the main bearings because of the unbalanced situation. Also if your having a hard time loacting this vibration, and your not sure if its the engine or tranny, easy way to find out is to unbolt the torque convertor, push it away a little(towards the transmission) and start it up. if now theres no vibration, you have narrowed it down to the transmission. If its still there, its an engine problem.

Thanks I will try that today cuz it is really getting bad, need to figure out what it is.

well i pulled the bults to the converter slid it back and started a little smother but still there. That was last week, well today i go out to start it and battery is dead go buy a new one start it up purrs like a kitten and no vibration at all. Strange but also it is really cold today (16*) could that maybe have stiffened the rubber in the dampner and made it not vibrate so bad. Havent had a chance to look at anything since pullin the torque converter bolts.

. Strange but also it is really cold today (16*) could that maybe have stiffened the rubber in the dampner and made it not vibrate so bad.

It could have, it is possible. Maybe the vibration was coming from a bad running engine. The old bad battery was just keeping the engine going, but was boarderline. That could have been the case too. Either way, hopefully it stays running good for you.

Thanks il see what happens with it.