Hello guys. I have a 91 W150 with a 5.2. I bought this truck used last summer. I am experiencing an engine vibration throughout acceleration... it runs pretty smooth at idle. This is not a drive line vibration. I have replaced the plugs, cap, rotor, wires, vibration dampener, TPS, coil, fuel filter and fuel lines. I also pulled the valve cover to look for a sticky valve. I used a infrared gun to check exhaust temps and they all looked fine. I checked the timing and it was only a little off. There is no check engine light either. The engine doesn't knock so I don't believe its a bad bearing. Any thoughts?

 

have you checked the motor mounts and universal joints?

 

The motor mounts look good as far as I can tell. The engine will vibrate when accelerated in park or neutral. If you let off the gas while driving down the road the vibrations smooth out so I don't think a u-joint problem.

 

Could be the torque converter if it's an auto.

 

Look for vacuum leaks too. Spray ailttle carb cleaner around the intake base and all your hoses and listen for idle up. Had people tell me they had transmission slipping before and it turned out to be air leaks.

 

If trans or motor has been worked on someone May have put a 360 converter or harmonic balancer on the 318 or vice versa. 360 is externally balanced and a 318 is internally balanced. I seen this situation 1 time and it was a bad shake in the motor. Turned out torque converter was bad and they put one in out of a 318. I hope this helps.

 

Spray at the throttle shaft also, the housing wears over time.

 

Crossroads1313 is probably close, I've seen it that in Dodge truck, ran into it in later models. The 360 converter has weights on it. Loose converter bolt or cracked flywheel usually cause different noises. I just looked up your's on Aldata and it has surprisingly little info on older stuff. I have the 82-14 on a seperate hard drive and it's about useless before 95. Found better info in Haynes or Chilton.