Vibrating noise just before gear shift

revitup

Just purchased a 97 F150 V8 with 89000 miles. Didn't notice before, but somewhere between 43-45 MPH and/or 1900-2000 RPM's there is a vibration noise similar to driving over those rumble strips they put along the side of the road. It only lasts for a second or two, just long enough for the gear to shift and then goes away. And it doesn't happen every time. Any suggestions on what to pursue are appreciated. Thanks all.

mullins87

Change the tranny fluid and filter. Ford's are bad about this. It will only do this under moderate acceleration, correct? This is the torque convertor lock-up shudder. The tranny in your truck is real bad about "cooking" tranny fluid real fast. If you plan on keeping it for a while, put an aux. cooler on it when you change the fluid. Go with a good quality synthetic also.

revitup

You are right on target! I knew I could count on Town Hall folks to come thru. Yes it only occurs during moderate acceleration. Thanks for the help and the direction. Now for a question from someone who is just venturing into the do-it-yourself care repair. Is the aux cooler something I can put on myself? and what is considered a good synthetic?
thanks again

mullins87

If you have an average amount of mechanical ability, you can easily put a cooler on yourself. If you are good at following directions and visualizing how things will fit together, you can still do it even if you have never done anything like this before.

People are going to disagree with me on this recommendation, but I have actual fact and experience to back it up. When you install the cooler, hook the cooler up so that the fluid will follow this sequence; 1. Fluid leaves tranny and travels to the aux. cooler; 2. Fluid then leaves the aux. cooler and travels to the factory installed cooler in the radiator; 3. Fluid leaves factory cooler in radiator and travels back to the tranny.

This is very important. If you live in an area that sees temps much below 50, the torque convertor won't function properly if you connect the aux. cooler so that it cools the fluid after it goes through the factory cooler. The factory cooler lowers the fluid temp. to something under 180 to 190 degrees, or at least is supposed to. If you install the cooler so that the fluid then goes through the aux. cooler after the factory cooler, then the fluid will be too cold when it reaches the tranny. There most likely is a temp. switch that senses fluid temp. and will not let the torque convertor lock-up if the fluid is too cold.

Now, if you install the cooler the way I recommend, the factory cooler will actually warm the fluid to proper operating temp. in some cold weather situations. This is because the aux. cooler is too efficient in cold weather. I told you all this because I had it happen to me on a truck I once owned. I followed the instructions that came with the cooler and installed it the way they said. When I got done, my torque convertor wouldn't lock-up on cooler days. I thought my torque convertor was shot, so I went to a tranny shop to get estimates. The guy at the shop spotted the new cooler and asked about its installation and said if I would reverse the fluid direction, the torque convertor would work. I did and it worked.

I hope I haven't scared you off this project, just make sure which line supplies fluid to the factory cooler and use that one.

As far as a good synthetic fluid, use Mobil 1 if it's available to you. Don't use the Aamco brand fluid that AutoZone/Advance sells. I've used it in my wife's Cougar and have not been impressed with it. I've had good luck with Havoline ATF, but not sure if I have ever seen it in synthetic.

Sorry for such a long post, hope this helps.

revitup

No reason to be sorry, this is just the information I need. I live in Northwest Ohio and the temps get below 50 at a moments notice.
I shall attempt this myself. I figure if I can replace the starter on my 92 Park Avenue, I stand a good chance at installing an oil cooler. Thanks for all the great info mullins87 you've been a great help.

mullins87

Yep, if you can handle a starter swap, you can handle this.