Trans problem I think [need help]

[SHANES SOCAL 70 K5]

I just replaced my engine in my 70 k5 350 to a th350 np205. Now I think my trans is going out. When I have been driving for about a hr. I notice it gets a little sluggish, and when I put it in reverse it starts to skip and hop. Only when its hot. All seems OK when I first start driving. One more thing I did, was replace the trans filter and fluid. I'm thinking I put the filter in properly, but don't know what problems that would cause. All help would be appreciated, thanks be for hand.

 

[4X4HIGH]

Have you checked the fluid level once the trans is hot? Sounds like it might be low. Also after checking the fluid level if it is showing full then you might drop the pan and double check that the filter hasn't come off or something.

 

[SHANES SOCAL 70 K5]

I have checked the fluid level at a lot of different times, cold and running, and hot and running. It shows a little over on the dip 1/8 in or so. I guess I will have to pull the pan. I was hopping that would not be necessary wright at first, new fluid and all. Thanks for your input 4x4 high

 

[Greg Ducato]

It's worth checking all the easy stuff first, while you are poking around, make sure the vacuum line from manifold to trans is not coked up with carbon or sludge. We have seen rare instances where the vacuum is actually stored in the line, reducing line pressure in the trans under throttle and creating stacked, sluggish shifts. If the modulator is an adjustable style, two or three turns of the screw in the hose nipple clockwise will increase line pressure. If everything looks good in the pan and the vacuum line is free and clean and you still have the reverse shudder and sluggish shifts it may be rebuild time...

 

[SHANES SOCAL 70 K5]

It's worth checking all the easy stuff first, while you are poking around, make sure the vacuum line from manifold to trans is not coked up with carbon or sludge. We have seen rare instances where the vacuum is actually stored in the line, reducing line pressure in the trans under throttle and creating stacked, sluggish shifts. If the modulator is an adjustable style, two or three turns of the screw in the hose nipple clockwise will increase line pressure. If everything looks good in the pan and the vacuum line is free and clean and you still have the reverse shudder and sluggish shifts it may be rebuild time...

Thanks for the info. I will check all and let you know. As for the modulator, how do I tell if it is adjustable. I'm not a trans guy at all. I can take it out, and put it in. I have never done any thing else on a trans.

 

[4X4HIGH]

If the modulator is adjustable you will be able to pull the vacuum line off and use a small screw driver through the vacuum port and there will be a screw that you turn. I doubt you can look into the hole and see anything so just find a straight blade screw driver that fits into the hole and see if you can feel a slot that it will drop into.