I have an 89 Crown vic. when driving from a stop, It will shift into 2nd smooth as butter, but when going into third; it just revs and will not shift. It acts as though third is not there. A mechanic has told me that when you left off the accelorator it acts like it shifts into third, but when you step on the accelerator again it is gone. I have not changed the tranny oil or filter. Any thoughts? Is this a common problem that can be repaired without dropping and reinstalling a new/used tranny?

Hi, if when you move the gear stick into 3rd gear position if the stick stays where 3rd gear should then the problem is going to be in the box itself.

If you can get 1st gear with no problems and the car drives ok in 1st then shift to 2nd if this also drives ok then when you put it into 3rd if the gear stick is in 3rd gear position and it goes into that position as it normally does then the problem is going to be with the teeth on the spline that is the 3rd gear. You will need to remove the gear box no matter what you decide to do.

Now you have 2 options the first and easiest would be to get the gearbox replaced with a second hand one or reconditioned box. Buying new would be to expensive and a second hand or recon box will do you just fine.

The second option and more time consuming would be to remove the box strip the box down and replace the parts that need replacing this is only a good idea if: a, you have stripped a box before and put one back together, b, if you can get hold of the exact part you need this can be difficult as not many places sell the spares to put inside the box.

Now as for the cost if a garage was doing the work then replacing the whole box would be cheaper as their is less labour involved in removing and replacing a complete box.

If a garage was removing the box then strip it down to replace parts then this would work out more expensive on labour but cheaper on the cost of parts.

Now what i would do would be to locate a second hand box from either breakers yard or off somewhere like ebay then you get the box yourself and get garage to fit or do it yourself if you can manage this sort of work.
Replacing the box with second hand one or recon one would be cheaper than paying someone to strip your box down replace the parts then refit on the car, the problem as your box has started to fail you could replace the part then find out something else goes wrong a month later. This is where buying a recon box would be a better option as you would get some warranty.

Now if you car drives ok in 1st and 2nd gear then you know the clutch is fine and the gear selector rods are fine then the problem can only be with the drive inside the gearbox you will probably find that the cogs on the end of the drive for third has either stripped the teeth off so its not engaging the drive or the weld holding the cog on could have split this also not engaging the drive for that gear.

Im sorry their is no easy fix for this but it is a case of removing the box and replacing its up to you what you want to do but i would replace the box with either good second hand one or trade yours for a recon they usually knock some money off if you trade in your box with them.
You would need to ring around a few garages to see if they can get you a recon box.

Let me know how you get on or if you need further assistance ok