Tranny trouble?

[eminem3150]

When I am cruising at a steady speed it feels like the car will sometimes shift from 4th to 3rd and back to 4th repeatedly. It does this intermittently but is very noticeable when it happens. The tranny is original with 122k miles. Is it time for a rebuild?

 

[rubydist]

how much does the tach change when this happens?

 

[jonreese]

have dead 97 with only 7k on ford warr tranny. whole car 110k good shape.pinned cams but valves bent b4 pinned and welded. sell for some over scrape. jon reese iowa

 

[eminem3150]

how much does the tach change when this happens?

about 50 rpm and the speed usually remains constant when i am cruising at 45mph. sometimes will drop a couple mph but i can defiantly feel when the rpms are changing.

 

[rubydist]

Sounds more like the torque converter is unlocking and relocking. This can happen for several reasons, the most common of which are that the pcm thinks the trans oil temp is too low or that the vss is bad. Both of those typically set codes, so pulling the codes would be a good next step.

 

[shotime1994]

Sounds more like the torque converter is unlocking and relocking. This can happen for several reasons, the most common of which are that the pcm thinks the trans oil temp is too low or that the vss is bad. Both of those typically set codes, so pulling the codes would be a good next step.

I agree with you. Also does it hapapen on flat ground or while you are going up a slight hill?

 

[eminem3150]

I have only experienced this on flat ground since there are not many hill here in Florida. I will check my codes. Where is the trans oil temp sensor?

 

[eminem3150]

I forgot to mention that the car has the same problem in AND out of overdrive.

 

[shotime1994]

The trans temp sensor is on the side of the trans behind the cover.

 

[whiteguy3]

I

forgot to mention that the car has the same problem in AND out of overdrive.

Good to know. Because 4th gear is also referred to as overdrive and if your car had an issue with gears themselves or a clutch-pack it would not do it with OD off because '4th gear' is turned off when OD is turned off.

My bet is that it is a torque converter issue. Either the fluid is really too cold and the torque converter is unlocking due to temperature. Probably not VSS related and normally if the transmission temp sensor senses that the torque converter cannot lock up because of temperature it will set a code. Not necessarily the engine light.

Do you have the stock lines and cooler or do you have another cooler installed?

 

[whiteguy3]

The trans temp sensor is on the side of the trans behind the cover.

LOL...It's funny you say that because this trans is freakin' huge and it is on both sides because of the enclosed half shaft. So it' on the driver's side behind the pan.

 

[eminem3150]

I

Good to know. Because 4th gear is also referred to as overdrive and if your car had an issue with gears themselves or a clutch-pack it would not do it with OD off because '4th gear' is turned off when OD is turned off.

My bet is that it is a torque converter issue. Either the fluid is really too cold and the torque converter is unlocking due to temperature. Probably not VSS related and normally if the transmission temp sensor senses that the torque converter cannot lock up because of temperature it will set a code. Not necessarily the engine light.

Do you have the stock lines and cooler or do you have another cooler installed?

I have the stock cooler and lines installed. The problem happens often even after a long highway drive. The trans fluid is dark. Would a flush help me?

 

[eminem3150]

Should I flush my tranny fluid???

 

[Guido0136]

If the fluid is dark and perhaps old, I don't see how a flush and fill could hurt.
Give ita try and report back to us.