Occasional "Clunk" sound while accelerating near 20 mph

[jvano]

I was wondering what would cause an occasional "Clunk" sound when I accelerate to 20 mph and let off the gas? It almost feels as if I hit something. I have 75,000 miles on my '04 X. All other gears shift excellent, right when they're supposed to. Actually all the gears shift good, it's just very intermittent when I approach 20 mph which is right before a shift to 2nd gear I believe. I was just wondering what the possible causes of this could be. I also have a squeak coming from the driver side front tire when I go over a bump, any ideas on that either? Other than these 2 things I love the truck. Thanks in Advance for the help!!

 

[sethmorgan]

Could be driveshaft universal joints

 

[1AJeremyD]

Do you feel the clunk at all or is it just audible?

 

[jvano]

I can feel the clunk as well as hear it. It's very intermittent though, and doesn't happen all the time. I will definitely have the driveshaft universal joints checked out.

 

[tower]

The squeak would be the sway bar bushings.

 

[jvano]

Thank you for the reply!! I will defnitely have the sway bar bushings checked out by my mechanic. By any chance you wouldn't know the approximate cost to replace them would you?

 

[tower]

Well did mine myself so about $9 and 20-30 mins of my time.

 

[jvano]

Really? That cheap. That's awesome, thanks for the info!!

 

[neilpridenz]

Hi, I have both those problems on my 2004 XLT.

You can confirm the squeaking is the sway bar bush by spraying some silicon spray like WD40 into the rubber bush, get as much inbetween the bush and the sway bar as you can. Wheel best taken off and vehicle jacked up.
The silicon spray will creep in and quieten squeak for a few days before it dries up.

I suspect my clunk going 1-2 is valve body gasket in tranny, getting mine changed soon so will let you know how it goes.

Neil.

 

[jvano]

It's good to know other people are having the same problems as me. Thanks for the reply, and if you could give me a price range on the valve body gasket I would appreciate it. Thanks again!!

 

[neilpridenz]

I was quoted NZ$450-500 for dropping the pan, changing filter, changing valve body gasket new pan gasket and refill with 12L Mercon V fluid. Thats about US $350.

I reckon the valve body gasket and lablour only conributes about $75 to the job - and I was going to get it flushed anyway.

Take a look at this vid - very good demo of what gets done.

http://www.youtube.com/watch?v=HaHIK-dwhbA

Neil.

 

[jvano]

Thanks for the video Neil, it gave me a good understanding of what the Valve Body Gasket is. I will have this checked out at my next scheduled service. When you get it done could you possibly let me know if it fixed the shifting issue? Thanks

 

[neilpridenz]

Sure - its booked for this Friday, I will let you know how it goes.

 

[sethmorgan]

I'm curious, how does a bad valve body gasket cause a clunk?

 

[1AJeremyD]

The reason there is a clunk is the solenoids do not pressurize properly and when it does it is a sudden jolt and bangs into gear. Normally if you do not take care of the issue you will end up having to do a complete rebuild of the transmission. Proper maintenance usually helps prolong the life of the transmission

 

[sethmorgan]

And the solenoids do not pressurize properly because the screen in the gasket is suspected of being clogged? or ripped/open? Or is this what the redesigned gasket took care of?

 

[neilpridenz]

Thats the thinking Seth. Gasket breaking down causes low or intermittent pressure to the solenoids disrupting the shifting.

My truck was diagnosed as needing new VB gasket mainly due to very harsh shifting D-R and R-D, but lately it also gives me a similarly harsh shift between 1-2. usually when I'm just driving slowly, say in heavy moving traffic. Started to happen more often recently.

Its enough to make you feel a slight kick in the seat of the pants when it happens, about twice a day now.

I'm no expert and I've no idea if my clunk comes from the same source as the one this thread was started about. I should know on Friday afternoon if the gasket fixes it though...

 

[sethmorgan]

Any update?

 

[neilpridenz]

Got a bit of an update, slightly inconclusive.

The explorer went in last week and had the ATF and filter changed, and the valve body gasket checked. (95,000kms on the clock)

The gasket was actually OK, it was replaced anyway along with the other standard gaskets in the kit (I think the servo and solenoid block gaskets). The valve body itself was resurfaced in case it was damaged.

I was happy enough to get the ATF changed, the replacement gaskets only cost me another $30 or so on top of the ATF and filter change so no great cost involved. The ATF was pretty gunky so I feel it was money well spent just to get that changed. Total bill NZ$540, about US$450.

Even though nothing was obviously fixed, the problem seems to have pretty much gone away! It shifts way more smoothly than it used to, and I have only felt the 'clunk' once in a weeks normal driving - and much less violent than before.

I now reckon the problem has been caused by a valve sticking occasionally and becoming free suddenly, or similar. The new fluid was significantly less viscous than the old, I think the better quality fluid has freed up whatever component was sticking and its all working more smoothly again.

One thing my transmission shop did tell me was that the Fords have frequent updates to the firmware in the computer that controls the transmission shifting. Normally these are picked up automatically and updated when Ford services the vehicle, but this one has never seen a ford mechanic since it was built - it has been serviced by non-ford places.

He reckoned it would be worth going to a ford place to get it checked for the latest updates, should only cost an hours labour. He couldnt do it for me as he didnt have the right equipment.

So I reckon my problem is about 75% resolved, I will get the firmware checked and call it quits for then. Once I put about another 30,000kms on the explorer I will get the ATF drained and replaced again as only about 2/3rds of the fluid would be changed so far, if I do the same again then only about 10% of the old fluid should still be left. Mercon V is kind of expensive though!

 

[sethmorgan]

Thanks for the update. Here's the sticky on the firmware: http://www.explorerforum.com/forums/showthread.php?t=228805