My tranny slips when accelerating at about 60 or when going up a hill, does much better when I shut o/d off but still slips occasionally. It is a lariat. Do you think it will need rebuilt or can it be fixed. It has been doing this for 8 months.

 

Truck details, please.

 

2004 ford f150 5.4 liter 4wd lariat automatic

 

If it's truly slipping then it can't be fixed without removing the transmission from the vehicle and getting to whatever needs to be replaced inside. When it gets to that point you wouldn't want anyone to just fix that problem because others will soon follow.

Hate to say it, but if it's slipping then it's tie for a rebuild.


Or, could it be a shudder you are feeling? If so, then most likely it's time to look at replacing ignition coil packs. A failing coil pack or packs will fool almost everyone without a lot of experience working with these that the transmission or torque converter is shuddering.

Can you exactly describe what it is you are feeling when it slips?

D

 

When going up a hill, I lose a lot of power and then it starts slipping

 

Im trying to get your impression of "slipping". What exactly do you feel or see that makes you say that it is slipping?

D

 

I feel a jolt kind of

 

Based on the very limited info I am hearing, I am betting that this is ignition related and not transmission slippage.

Can you see the engine RPM flare before this jolt happens?

D

 

Wouldn't a "slip" be a sharp increase in engine rpm accompanied by a feeling of loss of power or actual loss of speed? (i.e. a feeling that the vehicle is "coasting" in neutral and the engine is freewheeling.)

I'm just trying to help him understand your words "engine flare" here Darrin.

- Jack

 

Actually, not so much. That would have to be a terrible, horrible slip. Likely one that you wouldn't recover from and be able to drive normally anywhere at any time.

What you are describing is a lot more like dropping out of gear. This is what I think he is feeling if it is actually transmission related. The transmission dropping out of gear is a lot more likely to be a fluid supply issue to the clutches. Until it gets to the point of being much worse due to being neglected. Then you will definitely have a slip.

A slip will normally still pull enough to not freewheel. Unless it's so bad that it's already shot. But again, you aren't likely going to be driving that normally otherwise without knowing it. With a slip you will be able to hear that the engine is revving more than it should be for the pull that you are getting. Slip is like spinning your wheels in the rain. You are still moving, at least somewhat, but the contact surfaces have lost their grip. You may feel it nose over, but it usually isn't going to stop pulling enough to where the engine free revs.

Unless of course you keep giving it gas enough to burn the hell out of it and then it's just going to get worse until it won't pull anymore.

D