Clunk when accelerating

[hosejockey61]

Can anybody help me out? I had my tranny rebuilt less than two years ago. I took it to the shop and they don't think it's the tranny (naturally).

This clunk does NOT happen when starting from a stop. It occurs when I am going down the road...I'll let off the accelerator to slow down a bit and then when I press the accelerator it sounds like it slips just a bit before grabbing and making a clunking sound. It does this at speeds from 20-60 mph.

Could it be my rearend? I checked my u-joints and they are solid.

ANY help is appreciated!

 

[stamp11127]

Check all mountings to the engine, trans and cross member to make sure they are not loose. It does sound like a trans issue since the drive line is unloaded before you hear the clunk.
Get a second opinion on the trans.

 

[Moemantha]

Check rear lower knuckle to control arm bushings. They are called ball joints, but they have no ball lol. Mine were worn and the truck would knock on acceleration. Easy to check. Jack ul truck, and pry rear tires up. If there's play they be done.

 

[blue oval guy]

get a second opinion on the health of your U-joints. They sometimes appear ok but are not. be sure and check ALL driveline parts and not just your rear drive shaft. 5.4 motor makes a lot of torque especially with mods and will eat up components as normal wear and tear. please let us know what you find.

 

[beenbroken]

Mine did the same thing, only above 40 MPH, also had the common shudder issue. I would bet on it, easy fix = Complete Tranny Flush & Filter change or at least two pan drops, the second one after running a hundred miles or so. On my second pan drop, I placed Dr Tranny's Shudder Fix in the pan directly after cleaning it out, being careful not to spill any out during re-install. I simply done this because I am OCD and wanted to make certain that the entire tube was making it into the pan rather than clinging to the filler tube and funnel. Issue has been resolved for thousands of miles hopefully never to return. Ford had a TSB on this, which simply said to change the fluid to Merc V. A third Pan Drop and Filter change with another tube of Shudder Fix may be a good idea after a couple thousand miles or so. So, my issue was very similar with the addition of the shudder, the above eliminated both.

 

[metaldrgn]

Mine did the same thing, only above 40 MPH, also had the common shudder issue. I would bet on it, easy fix = Complete Tranny Flush & Filter change or at least two pan drops, the second one after running a hundred miles or so. On my second pan drop, I placed Dr Tranny's Shudder Fix in the pan directly after cleaning it out, being careful not to spill any out during re-install. I simply done this because I am OCD and wanted to make certain that the entire tube was making it into the pan rather than clinging to the filler tube and funnel. Issue has been resolved for thousands of miles hopefully never to return. Ford had a TSB on this, which simply said to change the fluid to Merc V. A third Pan Drop and Filter change with another tube of Shudder Fix may be a good idea after a couple thousand miles or so. So, my issue was very similar with the addition of the shudder, the above eliminated both.

You can do a flush by yourself. Nothing special required except a big pan to catch all the fluid and a cheap siphon pump to remove and replace the oil in the pan before flushing the rest of it. I did it with my 03 expedition. If you just change the fluid and filter you are only mixing around 5 quarts with 13.9 quarts then remixing it if you do it later. If you can do the math it's easier to see that it would be a waste of money and time to do it that way. I bought the cheap store brand mercon V at walmart and it works fine, but I didn't do it for the shutter problem.

 

[larshell]

Having the same problem with my 2005, I recently change tranny oil. Also pull down torque converter to remove the remaining oil. Change filter too. It was ok until one day it start to shudder on take off. Should I change the oil again? Thanks!

 

[1997SCEBFEX]

Sounds like torque converter to me.
Do you have a cel, or the O/D flashing??

PanHandler.

 

[larshell]

What is O/D flashing and cel sorry for my ignorance.

 

[metaldrgn]

O/D is overdrive and cel is check engine light. If I am not mistaken anyway

 

[larshell]

How do I flash O/D?
No cel as of now.

Sent from my SM-N9005 using Tapatalk

 

[Zap Rowsdower]

The Rowsdower mobile is experiencing this same issue.
I personally do not have a check engine light or the overdrive flashing while I'm experiencing this.

 

[larshell]

Oh i get it.
No O/D flahing and Cel here also.

Sent from my SM-N9005 using Tapatalk

 

[SailorKane]

I have the same issue. Clunk when accelerating. Its happening at a downshift and getting more pronounced as time passes. Original tranny fluid and filter. 120,000 miles on truck. Getting mixed opinions as to whether I should change the fluid at all. Some experts say I shouldn't do it, it might cause tranny to fail in a few thousand miles. Others say it shouldn't hurt. What is the TSB that Ford issued on the tranny? Change to Mercon V?

 

[1997SCEBFEX]

I have the same issue. Clunk when accelerating. Its happening at a downshift and getting more pronounced as time passes. Original tranny fluid and filter. 120,000 miles on truck. Getting mixed opinions as to whether I should change the fluid at all. Some experts say I shouldn't do it, it might cause tranny to fail in a few thousand miles. Others say it shouldn't hurt. What is the TSB that Ford issued on the tranny? Change to Mercon V?

I trailered a lot in my Expy's earlier days, thus changed the filter/fluid every 25K in addition to the oversized trans pan.

Q: What does you fluid look/smell like on the dipstick? I'd venture to say you're well beyond service life. I could be wrong, but with the hundreds & hundreds of heat cycles you've had on the life of the trans....time to change it out IMHO.

MERCON V is the latest fluid for these trannies.

PanHandler.

 

[larshell]

I don't have this clunking issue until change my oil. After few thousand km there it is.
I have it scanned at dealership there is VSS error any suggestion guys. Thanks!

 

[Zap Rowsdower]

Took the Rowsdower mobile into the stealership this morning and had the transmission fluid changed along with a new filter. On the drive home I didn't notice clunking when I accelerated.
I hope that solved the problem.

 

[SailorKane]

My fluid is slightly brown.
Rowsdower, please give update when you have some more miles on the vehicle. It is encouraging right now, however.....

 

[Zap Rowsdower]

My fluid is slightly brown.
Rowsdower, please give update when you have some more miles on the vehicle. It is encouraging right now, however.....

Understandable. I'll follow up in a week or two.
However, if I happen to forget. No news is good news!

 

[Zap Rowsdower]

It’s already been almost two weeks and I haven’t noticed the problem anymore.
I have to say it was a little pricey getting the transmission fluid changed at the dealership but considering I don’t have to deal with that clunking when I accelerate anymore, it was worth it!
-Rowsdower