Th350 questions

[Smokinthehippies]

Another newb question from me today.

My th350 is being a pain lately.
I found out that my kick down setup isn't hooked up and my the vacuum hose isn't either. Normally I wouldn't care but I'm trying to track down some problems right now. Obviously the kick down is pretty obvious. But what is the vacuum hose for. I'm assuming it goes to the yellow looking vacuum actuater type thing hanging off the back of the trans.

 

[owenst7]

But what is the vacuum hose for. I'm assuming it goes to the yellow looking vacuum actuater type thing hanging off the back of the trans.

Correct. Vacuum modulator.

 

[Smokinthehippies]

Correct. Vacuum modulator.

Ando I need that hooked up? Would that cause shifting issues.

 

[blazaroma]

The modulater controls the shifting of the trans, via vacuum from the engine

 

[Smokinthehippies]

The modulater controls the shifting of the trans, via vacuum from the engine

Ah very good. That def sounds like one of my problems.

 

[Smokinthehippies]

I don't suppose the vac mod has any bearing on why my truck in 2nd gear I'm only getting bout 25-30% of actual forward movement. While pushing the throttle. I can hear and see the rpms climb. And can hear a whirring-ish sound from below but can barely maintain speed. In first gear it rolls fine. Idk man.

 

[imiceman44]

I don't suppose the vac mod has any bearing on why my truck in 2nd gear I'm only getting bout 25-30% of actual forward movement. While pushing the throttle. I can hear and see the rpms climb. And can hear a whirring-ish sound from below but can barely maintain speed. In first gear it rolls fine. Idk man.

Well it sounds like you fried your tranny but hook up the vacuum line to the modulator and the kick down cable, and then check the fluid see if it's low.
If it's not low, and the tranny doesn't work right then you are done.

 

[Smokinthehippies]

Well it sounds like you fried your tranny but hook up the vacuum line to the modulator and the kick down cable, and then check the fluid see if it's low.
If it's not low, and the tranny doesn't work right then you are done.

Ah so I was afeard. I kno it's good on fluid bcuz it leaks out so much in the driveway that every time I drive it takes a quart or two. Think it's time to just sack up and do the 400.

Another question for you. If I hve a complete 400 trans sitting on the bench. Is there anyway to test its quality/ usability without ruining anything that would need to replaced before use. I'd rather not force myself to rebuild it if I don't have to.

 

[owenst7]

Ah so I was afeard. I kno it's good on fluid bcuz it leaks out so much in the driveway that every time I drive it takes a quart or two. Think it's time to just sack up and do the 400.

Another question for you. If I hve a complete 400 trans sitting on the bench. Is there anyway to test its quality/ usability without ruining anything that would need to replaced before use. I'd rather not force myself to rebuild it if I don't have to.

You can test most of the seals with a rubber tipped blow gun. You need a picture/map of the passages and when you pressurized them, you should hear a dull thud and no hissing (leaking air). You can also make sure the valves move freely in their bores.