i have a 2008 F350 6.4 liter 4x4 that has a slight clunking sound when coming to a stop and when initially starting off. The wrench light on the dash is on which is for drivetrain but the transmission seems to shift smoothly after the initial clunck, does anyone have any suggestions as to what this might be?

 

My suggestion is a bad u joint in the driveshaft. Have someone watch under the truck (from a safe, outside the truck, position) while you shift from Drive to Reverse. Better yet you should be able to push/pull/twist the driveshaft by hand (with the truck off) and see if any of the u joints show any movement at all.

If you are referring to the wrench light that comes up on the info center, this may be for a different reason. Does it come on every drive? Does it wait for the truck to warm up before coming on?

 

I crawled under the truck and tried to move the driveshaft and it's solid, the lit up wrench is on all the time from when I turn on the key to when I turn it off, but the transmission seems to shift fine.

 

Are your front hubs unlocked? Can you hear the noise when shifting from drive to reverse?

The wrench doesn't necessarily mean transmission. It can be any number of things, one of my previous trucks had it on because of a bad oil cooler, with the oil cooler the wrench doesn't come on until the truck is warmed up - that's why I asked.

If you have access to a scan tool, (friend or local parts store) it should tell you what is causing the wrench. I don't think a basic OBD reader will work.

 

Ford truck put together with clunk when stopping makes me think you need to grease the Slip joint in the driveshaft. Common superduty problem. Just make sure you mark where everything bolts up before you drop the shaft so you don’t get anything misaligned.

 

Thanks I try greasing the slip joint

 

the latest clunking cappuccino is to lube the drive shaft splines.

some folks pull the shaft out and lube the splines.

 

Drivetrain noises are some of the worst. Not easy to track down. And 6 or 7 things that could be causing the same noise. I have one currently that I am struggling with at the moment.

 

Firefighter - still no luck? Rear bearings were good?

Sorry thread hijack...

 

HAVent had a chance to get to the rear bearings yet. I am hoping for tomorrow. It’s been so stinking cold your hands are numb in about 5 min. Just got my driveshaft back from the shop today. New u joints and they said it had a bad wobble at low speeds. So I am really hoping tonight I will have some progress. For bad rear bearings what am I looking for? Scoring? Blue spots?

 

Sounds like they may have found the noise I would put it on and test drive before you dive into the bearings. If the noise is gone then there is nothing to look for on the bearings. If a bearing is bad enough to make an annoying road whine then you should be able to feel which one it is by turning the wheel by hand with the truck off the ground.

Just get that crappy looking fluid out of them and top off with more new oil.