QuestionQUESTION: Hey Wayne
I have a 1985 GMC pick-up 350 eng. 350THM.
I have a vibration when I rev the motor and when driving down the road. It seems to cycle, and only under a load.
The motor has been tuned by a professional and is misfiring,u-joints seem to be good also. I had the wheels balanced twice. I'm thinking maybe the trans, or torque converter????
ANSWER: Is that a typo? 'The motor has been tuned by a professional and is misfiring?" A missfire will definitely cause a vibration under load....
Wayne
---------- FOLLOW-UP ----------
QUESTION: Yes that is a typo the motor ISNOT misfiring.
ANSWER: Does the vibration exist in neutral? If you were to sit at a stop and rev it up a bit do you feel the vibration or does it have to be rolling.
w
---------- FOLLOW-UP ----------
QUESTION: Yes. It does vibrate in neutral when you rev it up. And also when going down the highway.
AnswerHey,
Have a cylinder balance test done or compression test just to make sure you arnt getting a low power output on one hole. Even though it might have all fresh ignition components and a good tune up you may have a valve problem or compression problem on a cylinder that is making it feel like a vibration. A converter would have to be pretty bad to cause a vibration in neutral enough that it probably would have shifting characteristics that would indicate transmission problems.
