I own a 1994 Mazda B2300/Ford Ranger. Ever since I have owned it, there has been a slight “thump” when you let off the accelerator. Annoying, but for a cheap truck, I just ignored it. NOW, there is a clunk when I lift off, and when I hit the accelerator after shifting gears. There has been a loud “rumble” sort of sound for about two weeks, and I was told by a mechanic that I needed a “cat back” exhaust. Okay, but when I rev the truck in the driveway, it doesn’t sound like the exhaust has issues. I DO get the rumble through the steering wheel and floor of the truck, and up until this morning, when I took the thing out of gear, or stepped on the clutch, the rumble sort of went away. Now, it doesn’t. I don’t have a lot of cash to spend, and want some ideas of what I might be looking at before I take it to a mechanic, and fall into their evil, boat-payment-making grasp!
Universal in the drive shaft. Not to worry if there is a slight “bump”. If it turns into a vibration in the seat of your pants at highway speeds, take it in to be serviced or replaced. If it has fittings, they should be regularly greased to prevent excessively fast were. It’s a normal wear item in rwd trucks.
The other problem is exhaust system hangers rusting which allow the system to vibrate against the chassis. You can drive that for a while longer. Failures within the exhaust system as the mechanic indicated is another possibility. Non is life threatening but the symptoms of all just get worse. So I would just drive it.
When cooled down, go under the truck and check out hangers and excessive play. You may be able to fabricate your own if that is the problem. Uses stainless steel though and not regular as they will just rust again. I have used SS hose clamps that lasted years. Pad them were possible.
I’m also thinking drive shaft. The rear axle might be torquing up under power and when the throttle is released the axle will quickly fall back to the ‘at rest’ position. If you park with the front bumper against an immovable object and alternately release the clutch enough to push forward and then release you should hear the noise. If you have someone else operate the clutch while you look at the rear axle and listen for the noise you might find that the axle’s front yoke will tip upward under power and drop down when power is off and cause the noise. Also, if there is a 2 piece drive shaft the hanger bearing might be torquing up. But please be careful. I would hate for someone to get hurt due to my suggestions. The truck can hop, the tires can throw loose gravel and if you come in contact with the spinning wheel serious injury can occur.
Also look at the rear of the transmission. If the transmission mount is failing the rear of the transmission can lift up when power is applied.
And I wonder how many shops have installed transmission mounts “gratis” while installing a cat back exhaust that wasn’t needed? But I’m just thinking “out loud.”
Also look at the engine mounts.