TH350 acting up

[lostsheep]

ok the trans in the t-top is doin funny sh*t and i gotta sort it out before thunder.

trans is a TH350 with stage 2 shift kit.

only when the trans is warmed up (cruise around town and a few hard pulls) ill be putting along in 3rd with VERY minimal throttle, just enough to hold speed and it randomly drops to 2nd but not fully. if you give it gas after it drops it pulls as it would in 2nd but if you let off it drops to a idle. manualy shift it down to 2nd while doing this and it goes into 2nd normaly, gives you good hard acceleration and deceleration. i made sure there was a good seal on all the vacume lines going to the vacume modulator and the kickdown cable is adjusted properly and the fluid is well within the operating range with car level idleing in park with the trans warm.

any idea whats doing this? faulty vacume modulator?

 

[RegalBegal]

Sounds like your vacuum modulator is going or you have a vacuum leak.

 

[lostsheep]

i myself suspect the vacume modulator. had someone also say possibly the govoner

 

[billyjack]

The modulator has more influence on light and medium-throttle shift points than the governor. Governor is mainly for heavy throttle and high rpm shifts.

Bill

 

[lostsheep]

basically what i thought. i will pickup a new modulator and give it a shot

 

[lostsheep]

well new modulator didn't change anything. i also figured out that when it does it if i click it into Neutral and rev it couple times and put it back in drive its fine for a few miles. also only does it when its hot. im thinking it might be a oil pressure problem, meybe the pumps getting weak?

 

[Pontiac455]

Sounds like a internal leak on the valvebody to me. Maybe one of the bolts have backed off in the valve body or it also could be that it picked up a bit of dirt. Take the pan off and have a look. If the pump was gettin weak yer line pressure would be low and cause havic in other gears as well.

 

[Pontiac455]

Reason why i say check the bolts in the valvbody is that when it gets hot the valvebody expands and cannot make a seal. Also check the bolts in the support plate.

 

[lostsheep]

car is going for a filter and fluid change on monday. was going to get them to also check over everything on the inside like valave body bolts.

 

[lostsheep]

well pontiac 455 nailed it. two bolt holes were stripped, one bolt was laying in the pan. they heli-coiled the holes and re-torqued the valve body and claened the wack of fillings out of the pan. they also put a gunk additive in to try and buy me some time but looks like its fried. now on the hunt for a 700r4 or if someone is selling their manual swap for a 5spd.

car still has same symptoms but goign to baby it around and see if the addictive will work but im doubting it.