Lately I've noticed a rumble strip sound when downshifting from overdrive to drive on our 04 FX4 (has 156,000 miles). It doesn't seem to matter what speed this happens at. Runs fine otherwise. I have not checked anything yet. Any thoughts? I suspect a tranny problem beginning to show.

 

Have you changed the transmission fluid lately? Is it when the trans is warm or cold? Check the fluid level, smell, and color. It should be a nice red color, shouldn't smell burnt. Try this first then you may have to run it by a transmission shop.

 

I have not changed the tranny fluid yet since we purchased it in Nov 2014. I would say this happens when warm. Level is good, smells like oil (no burnt smell), and isn't cherry red (seems red but not like new).

I'm assuming Mercron V is what is required. Is this correct?

 

Change the fluid and filter. Mine did the same thing at cruising speed slight uphill coming out of OD. I did a search on here at the time and found it to be a somewhat common issue.

 

Any brand filter & fluid recommended? About how much fluid is needed? I may add a drain plug to the pan while doing this.

 

Factory stuff is best. And good call on the drain plug. Im gonna do that next too.

 

Just be aware that a pan drop will only get about 5 quarts of fresh fluid; the tranny holds around 11 quarts. Most is in the torque converter which does not have a drain plug, So as soon as you start the truck, you'll be mixing 5 quarts of fresh oil with around6 to 7 quarts of old dirty fluid.

 

Dropped the pan, found the bobber plug, changed the filter, added a drain plug, & refilled with 5 quarts of Castrol Mercon V (I know I mixed it with the old dirty fluid). Went for a ride about 25 miles. Checked the fluid level in the middle of the run and at the end. Level is about 3/4 of the hot section. Everything seemed to be fine at this time. Will keep an eye on the fluid level over the next couple days.

To add the drain plug, I bought an engine oil pan drain plug (for GM with rubber seal, 12mm x 1.75 thread pitch) and a nut to fit. I drilled a hole, and welded the nut on the inside of the pan. I put the drain plug by the magnet because that corner the plug would interfere or come in contact with anything inside once the pan was put back in place.