th350 issues

[chevy111]

The TH350 in my blazer has some issues. I haven't done any poking around but heres what it's doing. First if I'm facing up a hill with it in gear it basically will roll backwards like it's in neutral unless I give it gas. Wont do this in park. Second it downshifts with minimal gas and almost seems to be searching for a lower gear at times. It's gutless as if the transmission is slipping when I get it the least bit stuck. It will Literally get up to 3 or 4 k on the tach and will spin no tires. Also I get lousy fuel mileage. Something like 8mpg on the highway. Guy before me said the transmission was rebuilt and supplied a receipt. Has maybe 500 miles on it. Is it possible it's shot or could it be something else?

 

[Z71paramedic]

Sounds to me like the torque converter isn't working right. Is the fluid full? Can you take it back to the shop that the work was done at and ask them?

 

[diesel4me]

I'd suspect it had a high stall speed torque converter installed,that will not apply power to the driveshaft until the engine revs up above 2000 rpms or so...either that or the stock one is dying,or the clutches are slipping,but the clutches should slip above that speed too if worn bad enough...the pump could be putting out low pressure too maybe,not enough to fully apply the clutches at lower rpms..

 

[chevy111]

It was rebuilt in 08 so I would think the warranty is long gone. It's mostly sat since the work was done. I haven't looked at the fluid, that's a good idea, I should have thought of that. From what I see on the receipt it doesn't say anything about the stall on the converter. Even if it was a really high stall I don't think it would do this. I have had it up to 4k and it basically would not spin any tires. Basically felt like it had no power just reved and moved the truck a little. I have a 2200 stall in my Chevelle and there's no way it wont spin both tires with the posi at that rpm. Im going to see if something might be hooked up wrong, fluid levels, and if nothing on that end I might pull it. I guess at least I didn't pay what he payed to have it done. 900 for the rebuild, 200 for the convertor and 400 in labor. I know a guy who will rebuild it with good parts for 600 and ill just do the labor myself. I would go overdrive but the LQ9 with a 4l80e is on the horizon.

 

[LVJimmy]

It was rebuilt in 08 so I would think the warranty is long gone. It's mostly sat since the work was done. I haven't looked at the fluid, that's a good idea, I should have thought of that. From what I see on the receipt it doesn't say anything about the stall on the converter. Even if it was a really high stall I don't think it would do this. I have had it up to 4k and it basically would not spin any tires. Basically felt like it had no power just reved and moved the truck a little. I have a 2200 stall in my Chevelle and there's no way it wont spin both tires with the posi at that rpm. Im going to see if something might be hooked up wrong, fluid levels, and if nothing on that end I might pull it. I guess at least I didn't pay what he payed to have it done. 900 for the rebuild, 200 for the convertor and 400 in labor. I know a guy who will rebuild it with good parts for 600 and ill just do the labor myself. I would go overdrive but the LQ9 with a 4l80e is on the horizon.

I have had good luck in the past reviving thm350s by changing from dexron to type F fluid. Might be a cheap way of getting a fw more miles out of it.