th350 issues

[WVscottsdale]

I finally got the conversion ujoint for my 1 ton rear axle but the brakes were rusted and had it locked so used low gear in the transfercase and reverse (cuase of the higher gear ratio) to free the brakes. Got brakes started to move but then I lost reverse. Forward is still working fine infact used forward to finish freeing brakes now truck drives fine but no reverse. Thinking I blew and oring but not sure. Not 100% on auto trans I work on heavy equip and heavy trucks more on the engine side or manual trans. Any help please

 

[WVscottsdale]

forgot to say that it wont even pull down the rpm or lunge back like it does in forward

 

[crazy4offroad]

If you blew the o-ring you would lose 1st gear too. Try manually shifting it into low, take off and manually cycle it through the gears and make sure you have all 3 forward gears.

 

[WVscottsdale]

i can feel the truck lunge in all at a standstill also lost reverse lights not sure if they are pressure regulated or interally linkage while i was driving it in low with the transfercase it shifted into second but not sure about 3rd didnt have alot of running room

 

[crazy4offroad]

1st/reverse share the same piston/clutch pack, so if you lose reverse AND first you can just about bet it's an internal issue. Reverse lights are switched on by a switch on the column, so it sounds like your linkage is out of adjustment. HOPEFULLY that is all but if not you may need to drop the pan and look at the shifter detents and the Reverse and Modulator Boost Valve "B-4" in this diagram, the valve could be sticking...
http://pages.suddenlink.net/crazy4offroad/storage/TH350 Valve Body Exploded View.jpg
Meanwhile keep an eye on that fluid, post back if it looks like it is turning black.

 

[WVscottsdale]

thanks ill look tomorrow dont think its the linkage cause it was working then as it started to move the wheels it just quit, heard a noise but couldnt tell if it was the brakes freeing or the trans.

 

[crazy4offroad]

Broken motor mount or trans mount can cause the linkage to get out of whack, have someone watch the reverse lights while you go through the gears on the shifter. The switch for the lights is on the column.

 

[WVscottsdale]

good job for my wife lol

 

[bucket]

My linkage is adjusted good enough that it works fine, but the reverse lights only come on and stay on if you hold up on the shift lever a little. So the reverse lights being operational (or not) aren't a sure sign.

Have you tried letting the truck sit while the shifter is in reverse to see if reverse might be lazy? Mine was like that for years and the delay got much longer over time, especially on a cold start. If the engine was warmed up it would usually go right into reverse, so I backed in everywhere I parked. Then I could just pull right out on a cold start. Otherwise I would have to sit with the truck running, shifter in reverse, foot on brake... eventually it would kick right into reverse. Now it's going out finally I think. It always goes into reverse, even on a cold start, but it slips and shudders if you give it too much gas.

Anyway, try letting it sit in reverse and slightly blip the throttle every now and then. It might go into reverse.

 

[WVscottsdale]

didnt get to check it out today preping for the storm thats coming our way but hopefully i will one day this week thanks for the help

 

[WVscottsdale]

im gonna have time tomoorow to look at it is there anything else i can try or look for tomorrow. Im a mechanic so i can fix just about anything but just never fooled with the autos

 

[WVscottsdale]

Ok took pan off found small debris also dropped th e valce body and the boost valve that is behind the reverse valve was stuck didnt find anything in it but cleaned and reinstalled and jusr need to oil in

 

[WVscottsdale]

no change boost valve was stuck but after i put it backtogether raised up the rear axle on blocks and the tires and driveshaft goes in the forward direction in reverse and forward. I'm guessing a rebuild in in order