Over Drive issues

[Vern60]

Hi I have a 1985 Monte ss,8.5 yrs ago I swapped out for a 350hp 350 and anew 200r4,it's been a great car but the problem I am having is that until recently when cruising around and it shifts into 4th the rpms don't go down like they used to,examples 50 mph it would be just over2000 now it's up to3000and at 65 it would be at3000 now it's at 4000,I'm just kind of baffled any idea what I should look at to correct this? My gas mileage is suffering bad

 

[pontiacgp]

Lock up is not engaging...

 

[Vern60]

Maybe it's in the switch?

 

[Rob-Legacy1]

You have no 4th gear.

 

[pontiacgp]

You have no 4th gear.

he said he has 4th, don't you believe him?

 

[Rob-Legacy1]

4th gear is not operating. lock-up only makes a 2-300 rpm difference

 

[Zeus785]

So you counted 4 shifts? Lock up should not be a 1000 rpm drop. 200-500 rpm drop usually on lock up.

If it is shifting 4 times and not dropping, there could be a valve sticking, cable not adjusted, or it is slipping real bad.

Can you suck out the oil into a clean container and inspect it for shavings or other debris? I would start there with your trouble shooting.

JMO

 

[olds307 and 403]

How is reverse? It sounds like the 3/4 clutch pack is dying.

 

[UNGN]

Put it up on jackstands and see what it does with no load on the drive train and document what it is doing.. If a clutch pack is sliping don't drive it because it will burn up, then grenade.