Transmssion Question

[Jose]

So I have a 2002 Ford F-150 with around 210K miles on it. I'm starting to hear a slight "thunk" (for lack of a better word) when I'm in OD and give it a little gas and it downshifts into third gear. Fluid level is fine. I've had the transmission fluid and filter changed before about 6 or 7 years ago. I was thinking about doing it again but a friend of mine is telling me that I will probably make the problem worse. I have no idea what sort of problem I'm having and I'm hoping this will help it and not make it worse.

Any thoughts on this? Should I go ahead and do a transmission fluid and filter change or is it not a good idea?

[lilvega]

My 2005 Expedition does the same thing. OD to 3rd downshift thunks. To me it feels like a bad U joint on the drive shaft but I have been too lazy to crawl under there and check it out.

[Denny]

That's what happened with my Lincoln right before I lost OD altogether. I'm not knowledgeable with autos, but the guy that fixed it said the OD pump was gone and some bands were stretched.

I didn't really care, just rebuild it.

[4EyedTurd]

Why do people say changing a trans filter and fluid on a high mileage auto trans is bad for it?

[lowthreeohz]

Why do people say changing a trans filter and fluid on a high mileage auto trans is bad for it?

I've always heard the junk in the existing fluid helps it out, never knew whether to believe it though

[Chas_svo]

I think it goes back to shops not wanting to do it, as then they get blamed when the tranny fails soon after.

If it were mine, I'd change and flush.

[Jose]

My 2005 Expedition does the same thing. OD to 3rd downshift thunks. To me it feels like a bad U joint on the drive shaft but I have been too lazy to crawl under there and check it out.

Why wouldn't you hear it under other gear changes though?

That's what happened with my Lincoln right before I lost OD altogether. I'm not knowledgeable with autos, but the guy that fixed it said the OD pump was gone and some bands were stretched.

I didn't really care, just rebuild it.

That's almost what I'm thinking as well. But I've been wanting to buy a new truck this year and this is a good enough excuse to go ahead and do so.

Why do people say changing a trans filter and fluid on a high mileage auto trans is bad for it?

I've always heard the junk in the existing fluid helps it out, never knew whether to believe it though

I think it goes back to shops not wanting to do it, as then they get blamed when the tranny fails soon after.

If it were mine, I'd change and flush.

To me this is the automotive equivalent of an old wives tale. I know around the same time I did the trans fluid and filter change I also did a gear oil change on the rear end. This was all done before I did a long trip and although everything went fine on the trip, over the next year or so I started getting a perceptible whine and I got it rebuilt. Granted I know I didn't follow any sort of prescribed maintenance schedule when it came to changing out the trans and rear end fluids but I've never beat up in either.

I'm going to go ahead and get the trans fluid and filter change done this week and go from there. I'm planning on buying a new(ish) truck this year and this may or may not accelerate those plans.

[UserX]

Check the tranny mount before doing anything to the transmission.

[UserX]

Why do people say changing a trans filter and fluid on a high mileage auto trans is bad for it?

If the clutch packs are worn, fresh tranny fluid can cause additonal slippage. I don't think that's the case here if he's hearing a clunk and it's not slipping now.

[Jose]

Check the tranny mount before doing anything to the transmission.

Good idea. Thanks!

[UserX]

Good idea. Thanks!

Every clunk I've ever felt in a tranny, was the result of deteriorated rubber in the mount allowing movement. Cheap and easy fix

[Jose]

Every clunk I've ever felt in a tranny, was the result of deteriorated rubber in the mount allowing movement. Cheap and easy fix

Jeezz I hope it's something that simple. Thanks for the tip.

[dcs13]

Any chance the carrier bearing is out ? That will thunk and click..

[Chas_svo]

To me this is the automotive equivalent of an old wives tale. I know around the same time I did the trans fluid and filter change I also did a gear oil change on the rear end. This was all done before I did a long trip and although everything went fine on the trip, over the next year or so I started getting a perceptible whine and I got it rebuilt. Granted I know I didn't follow any sort of prescribed maintenance schedule when it came to changing out the trans and rear end fluids but I've never beat up in either.

I'm going to go ahead and get the trans fluid and filter change done this week and go from there. I'm planning on buying a new(ish) truck this year and this may or may not accelerate those plans.

The rest of the story is that people usually wait until the trans is slipping, clunking, or not shifting correctly, then change the filter. It's better to follow the maintenance schedule. Not picking at you, just describing issues I've seen people go thru.

[dsrtuckteezy]

To me this is the automotive equivalent of an old wives tale.

Could be, but it held true in my case. Have a Honda civic that had 160k+ miles at the time, and changed the trans fluid (5spd) just thinking normal maintenance. Trans was fine before and then shortly after couldn't get it in 5th or reverse. The guy at i35 transmissions told me when it comes to a car with that many miles, kind of a "if it ain't broke don't fix it" deal