Help! F150 clunks from standstill
filed in 1994 Ford F150
Question: I have a 1994 Ford F150 4X4, 302/V8, E4OD Auto Trans and have noticed a “clunk” when starting from a stop with the tranny in “D”. I have had the vehicle back to the dealer with this problem, but they have not been able to fix it. When I finally got the service manager to take a test drive, he indicated that this was “normal”. I know it is not, as others I know with a similar vehicle do not have this problem.
I have checked the engine mounts and tranny mounts and they seem OK. I also have checked the Ujoints for play and they too are OK. The problem seems to diminish with a load in the bed, and when the engine (and weather) is warm. It is not an intermittant problem, so I should be easy to find (Sure…). If I were to describe the symptom, it feels like a worn U-joint, but like I said, U-joints are OK. Besides this is a new truck (16K miles).
Answer: I’m not much of a mechanic, but have you tried it in other gears, like 2 or 1 or R? If it does it in all gears, I’d imagine it’s after a certain part of the transmission. If it does it only in D and not in any other gear, it would sound like it’s in the tranny.
Just speculating. It’s always helpful to not let the mechanics get by with any speculating that’s not supported by the facts.
Does this clunk occur when you put it in gear or when you let up on the brake and apply power? My old 85 clunks pretty good when you put it in gear, but not when you drive off. Course, my idle is too high, too.
I have an ‘81 which does the same thing, primarily since I’ve boosted the idle speed up so it has better cold weather idling prospects. During the warmer periods, I set the idle speed down to a lower rpm, and the problem goes away. One thing to make sure of is to get an accurate idle speed setting. A number of electronic tachometers don’t actually “count” the ignition pulses, but instead measure a voltage and convert that number to a rpm reading (Fluke, et al). I use an optical tachometer which works well for idle speeds. Perhaps excessive ring gear/pinoin clearance? That could make a clunk, but would remain the same with changing load. A loose spring mounting or shackle? Try looking for this stuff. And do not assume just because a u-joint does not wiggle when it is grapped and shaken, it is good. The shaft should be removed from the car and inspected. Tho bad u-joints make other, uglier noises when launching from a stop (usually a clicking noise). Good luck
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