I bought my first truck, a 97 f-150 4x4 4.6 lt xlt about six months ago, it has 100,000 miles on it, and I'm really enjoying it. It looks and drives like new with the exception of a slight shudder which only occurs intermittently under light acceleration around 35 mph. I never notice it a highway speeds, just in town when driving slowly. It almost feels like the truck drove over a couple of small bumps or something similair on the road. I have had my mechanic replace the rear diff fluid, the transmission fluid and filter, the transfer case fluid, and the front diff fluid. He also installed a new air filter, all new plugs, new wires, and the fuel filter. The truck drives and idles beautifully but still has this shudder from time to time. I was wondering given the age of the truck if I should go ahead and try replacing the coil packs and would that possibly be the cause. Anyone know what these cost? Any advice or similair experiences would be greatly appreciated.
Thanks
Jimmy

 

Helped cure my shudder...

I think it's in the tranny still. The Valvoline has anti-shuddrer additives, and is made with the Ford tranny in mind.

Did you drain the torque converter too??
Just dropping the pan and changing the filter doesn't get out much fluid.
There are 14 quarts in there...draining the TC, and pan gets out 12 quarts.

 

Thanks Jim,
I asked about that when I picked it up and he said that he did not drain the torque converter. After reading your reply I found another post on torque converter "lock-up" and shuddering between 3rd and 4th gears being common in these transmissions once the mileage gets up. So as you've suggested, maybe that's what I'm experiencing.

Should I have the transmission pan pulled again if I get the torque converter drained?

 

Good advice, but here's what you wanna do first. Pull the drive shaft, mark it first so you put it back on exactly the way it was. Slide it out of the slip yoke, clean the spline with brake fluid , apply some good Teflon grease to the spline(a thin coat) . This is a known and common problem - do a search on slip yoke shudder within this forum, I posted the TSB a few times , I don't feel like looking it up right now(lazy) lol.

 

the 97-98 had a problem with the valve body's loosing pressure from poor design. so your most likely going to be replacing the valve body and torque convertor like i am to solve the same problem. i spent alotta money chasing down. but its torque convertor shutter. and id recomend replacing the valve body with a newer 03+ style. those were the best.

 

What trans you refering to Fast? One specific or both?

 

Thanks for all the advice guys,

I called Ford and the service person recommended I begin with a flush as it would be the most cost effective approach. Given the mileage on the truck it sounds like a good idea. He too suggested that it could be the valvebody being dirty, which would benefit from the flush, or possibly the solenoid on the valvebody.

As |I understand it, flushing and refilling the tranny, torque converter, and cooler lines etc, dosen't require dropping the pan so they would not be looking at the solenoid or valvebody initially.

If the flush doesn't fix it, then I'd have to have the pan dropped and further inspection done. I guess I'm just wondering why not drop the pan and inspect the valve body and if it looks good and the solenoid tests alright, replace the pan and then do the flush? Either way I think the full fluid change and flush would be a good idea, just not sure if I should have the valvebody checked first?

 

Read up on 'FLUSH' vs 'FLUID EXCHANGE'. A 'lush on an older, higher mileage tranny with an unknown previous service history can create other issues and headaches. Unless your truck came with complete service records, you have to ASSume nothing has ever been done with it. Apparently most dealers will do a 'power flush' (faster turn-around time for the shop) rather than the slower (and dare I say 'safer') fluid exchange. There's another thread on here - I think it's titled Fluid Change - where someone describes the difference and the 'dangers'. Check it out!

 

I wouldn't recommend a flush if the mileage is over 100,000 and hasn't been changed per the manual. However, a torque converter drain and fluid replacement will probably fix the problem. It did with my 1998.

 

Yeah, I posted quite a bit in that thread , I went to hell and back , but saved her I think - it's starting to shudder again a little bit , right after I get off the e-way from an 80mph run. Mine shudders just at take off , very little now though, allmost undetectable. I had mine on the bench in pieces, cleaning everything because I follow some one else flushing techniques and compromised my trans with contaminants. Not Fun!!!
I'm not sure what trans you have I have a 98 E4OD. What ever you do , don't flush the way some have described in the tranny forum. Just do it in three different stages - do not pump out any thru the line with truck running , this is not safe , with the 97 you do not need to do this. Two old timers told me the proper procedure and it's helped my problem ton's. I have a drain bolt on my pan, so I drain that first. I have a dual core radiator and two coolers from the factory - one is an oil cooler and the other a trans cooler. As soon as you drain the pan , pull the pan and then the filter, that's step 1. Step 2, unbolt the supply and return lines from your trans. Just unbolt for now. The get you a large ratchet and correct socket that fits your crank bolt. Line up your converter drain plug so that it's straight up and down. Pull the bolt and let your converter drain.
Step 3. With compressed air join the air hose to the supply line - dial in 40lbs of pressure only and let it run thru your lines (NOTE: WHEN DOING THIS PROCEDURE IT IS ADVISED THAT YOU HAVE A WATER SEPERATOR ON YOUR COMPRESSOR , YOU CAN ALSO RUN A CLEANER OR SOLVENT THRU YOUR LINES FOR BETTER RESULTS)
After about 10 minutes hook your air hose to your return line and do this for 10 minutes. Most of the contaminants are now flushed out of your cooler , but you need to re-hook to the supply line once more for 10 more minutes @ 60lb's max pressure to clear foreign matter and then the return line as well.
Install your new filter and bolt your cleaned pan and re-usable gasket back in place - crank the bolts to 120" lbs . Put your converter bolt back in. Reconnect your supply and return lines to the transmission.

That's it for draining and flushing.

Add 8 quarts threw your trans fill tube. Start truck , go threw the gears slowly and shut it off. Add 4 more and do the same. Add 2 more and do the same . Now check your fluid and add accordingly.

This is the fail safe way for a high mileage transmission.

If I were you I wouldn't touch my trans at all until I pulled the driveshaft and applied teflon grease to the splines. That might be your problem and theres even a TSB on it . It's definetly worth looking into and it doesn't take long.

 

That shudder is the torque convertor, my old 99 Expedition had the same problem.

 

The torque converter , the forward clutch, solenoid, driveshaft - could be any of the above really.