Hello all,
New to the forums and I just bought myself a 1990 F150 4.9l automatic 4x4 (push button OD, not sure which one this is yet) and there is an issue with it I can't put my finger on.

When I take off, if feels like something slips out of place and it seems like I lose over half power, when it shifts into second, there is a noise/vibration coming from the back, whatever slipped out goes back into place, and I have full power again. Happens only from 1st to 2nd shift. In 4wd, the same thing happens, only longer vibration/noise.

I'm thinking maybe trans, transfer case, or rear diff (since it's coming from the rear) I haven't taken anything apart yet till I go down to Milwaukee where I have all my tools and such. I'll only be down there for a few days and I'm going to rebuild the trans and rear diff whenI get down there. I just don't want to do both of these and have it be the xfer case. Any ideas?

 

Just checked this. 3.55 non-ls rear diff and E4OD trans. Was going to change filters and fluids today, but it's raining and I have no garage

 

tranny might be shot, id check your universal joints just incase, i know i got a wiked vibration (with speed) from the rear when my U joint was shot.

Definetly change the tranny fluid (WATCH THE PAINT!) and check to see if appears to be burnt or smells burnt. You could change the fluids in the read differential

 

Well, I changed the fluid in the rear diff and did a filter/fluid change on the trans and nothing changed. Fluids were rather dirty and in need of being changed, but that's about it. No damage to rear diff, no metal shavings that I could see. Researching farther and I've ruled out the rear diff as it's clean and there were no metal shavings of any kind in the housing or fluid. I've also ruled out the transfer case because there are no problems switching into 4wd high or low from 2wd.

So now I'm thinking it's a transmission and/or torque converter problem. Explaining the issue better. When I take off slowly these symptoms do not occur. It's only when I take off with a little bit of umph. Getting going, it seems like something slips out of place and there is some power loss. The engine still revs up and I am still gaining speed, just not as fast or with the power I should be. After everything seems to "catch up"/stop slipping/return into place, (this is all in first gear mind you) the trans makes the 1-2 shift. When the shift occurs and there is a rather intense driveline shudder for about 1-3 seconds then stops. Feels like its coming from the bed, which is why I suspected the rear diff, but that has been deemed to my eyes.

I read up a bit on torque converters and transmissions and this seems to explain most of the issues that I am having. Here's what I've found pointing at the TC and Trans...

Slippage- "Another problem that affects the operation of the torque converter is a condition called "transmission drainback." One-way check valves normally keep the torque converter full of fluid when the engine is shut off. But if the transmission input shaft bushings are worn, it can create a path for fluid to drain out of the converter back into the transmission. The loss of fluid from the torque converter can make the transmission feel as if it is slipping on initial take-off for about five to 10 seconds."

Torque converter. Adequately explains the issue I'm having. Happens when I am rolling at 1-10 and from dead stop. Accompanied by a ...

Driveline shudder- "Another driveability problem which may be blamed on the torque converter is a driveline shudder. A shudder may occur if the torque converter lockup clutch has problems engaging, usually because of low apply pressure. In most causes, the low pressure is an internal transmission problem, not a bad torque converter."

Transmission the target here. This is a 100% accurate description of the symptoms I'm having when trans shifts from 1-2.

Terrible gas mileage- "If a vehicle's fuel economy suddenly drops three to four miles per gallon, but the engine seems to be running normally (no misfiring or loss of power), the problem may be a lockup torque converter that isn't locking up. If the torque converter clutch (TCC) fails to engage, the vehicle will still drive normally, but with increased slippage between the engine and transmission. The underlying cause is usually a bad TCC solenoid, but loss of the vehicle speed input signal to the computer may also prevent the computer from energizing the TCC solenoid."

Because the gas mileage on this beast sucks.. harder than it should. Loss of power.. catch phrase there. I'm noticing a loss of power but to TC slippage? Does that count under this?

I'm wondering if anyone else has come across an issue similar to this. I don't want to throw a couple hundered dollars and a weekend at this thing and hope it works better by the "trial and error method" of automobile repair.
Sorry for the lengthy post btw.

 

I would say your it's your trans. The TC sounds like a good start. But what you just pulled up would also be a good explination. I think you are on the right track. You may just need to rebuild the tranny.

 

Rebuilding the transmission... Probably not as easy as it sounds. Sounds like I'm going to hit up a boneyard for a transmission or try to find a dirt cheap rebuild (Yeah...right). Everything I've read about rebuilding a transmission is "don't, get a used, rebuilt, or new one". How difficult would this be and how long do you think it would take if it were worked on nonstop? 2-5 days?

 

Relik, The time that it will take to rebuild a trans really depends on your mechanical ability and what you find when you open it up. If you have all the parts to rebuild it and you find nothing major wrong when you get in to it you should be able to do it in a day or two but don't forget nothing ever works out perfect. If you doubt your ability to take it apart and fix it then go look for a used one the worst thing is to take it apart and not be able to put it back together especially if you are away from home and it is your only ride well good luck

 

I called Ford service and described my problem and they said it probably is a bad torque converter. My symptoms as I described them to the service guy do not seem at all to be the same as described in this forum for a bad torque converter.

My case is the engine seems to 'cut out' or jerk momentarily while there is a load on the engine, such as going up hills towing something. When I turn off the overdrive and the RPM's rise then the symptoms seem to go away.

Does that sound like a torque converter? Thanks for any help.
Mike

 

Does it have the E4OD?

Is the CEL on? Have you checked for codes even if its not?

Was the fluid burnt? Has it ever leaked tranny fluid out the front seal (pump seal) but then stops once the truck cools down say over night, but then drips or leaks a steady stream once driven and hot again?

 

You could check for the simple things like broken motor or tranny mounts or missing or loose bolts.