'88 Ranger Cabin Vibes on Throttle Only

[dcpppf]

Hello all. I recently swapped the a4ld out and put in an FM146 and the truck feels SO much better. Now that it has some pep and isn't such a burden to drive around town I'm more inclined to fix the smaller nuances and hopefully make it more comfortable.

I've put around 500 miles on it the past couple of days and one of the more prominent annoyances is the vibrations felt in the cabin. I'm trying to better convince myself that it is the motor mounts, or hear what some folks on here think it may be. Basically I feel nothing through the steering wheel, but the cab of the truck just has a hollow vibration while on the throttle. and about half a second after I let off the throttle (completely) it's whisper quiet and smooth as hell, but then the second I barely crack the throttle (even if I barely open it while coasting at 60-65mph) it immediately starts the vibrations again.

So the fact that it COMPLETELY disappears while the throttle is closed is making me think the motor mounts might be due to replace. Couldn't tell you how old they are, but if I had to guess they would be original. My 2nd guess is something on the drive line, but not real sure where to start there.

Thanks for any insight!

 

[Cees Klumper]

Maybe you can check the mounts by putting a jack under the engine and just slightly lifting it, see what happens at the mounts when you do. Or wedge a pry bar in there, see whether the mounts seem ok. You can also have someone rev the engine (in neutral) while you observe what happens to the engine.

I had vibration in my cab but that was while driving on bad road surface and turned out to be the cab mount bolts not being centered and touching the body. Loosening a couple of them made them shift back to where they belonged (I had had a minor accident that caused this, it caused the whole cab to shift forward when I hit someone's trailer hitch with my bumper - so the chassis stopped dead while the cab was able to keep moving a couple milimeters, thanks to the body mounting rubbers. But this is not your issue it sounds like.