350 Turbo Transmission Question

I have an 83 chevy silverado 4x4. It has sat for about 4 months. The truck will crand and go in reverse fine, but will not go forward. The transmission only has about 20,000 miles on it. Have tried to switch gears and let it sit to get everything lubed back up, but that didn't work. Any ideas out there? Thanks for the help.

Did you check the fluid level?

i have had that happen on a truck i had sit for 4 years. dropped the trans pan and did a fluid filter change. still did not move right away but after let it heat up it did fine. still is. been 2 years.

Thanks for the help guys. Fluid levels are good. I have heard from a few people that I am going to have to drop the pan. I guess that's my only option. Thanks for the advice.

Single Shot while you have the pan out go ahead and drill and tap you a drain plug in there.

If the fluid looks Ok, and you have a solid Rev. don't worry about dropping the pan just yet, Go to Napa buy you a can of trans medic, make sure it has a seal conditioner in it, it should say,"stops leaks" the 350 trans is bad about the clutch drum lip seals getting hard and not sealing, it takes a lot of heat to make them pliable again, the conditioner with attack the seal and soften it. people has used brake fluid to do the same thing, but it only takes a little , to much and a seal that is as big as your hand will go over your head.

didn't work

This didn't work, any other ideas?

Did You Know.....?

Single Shot said:

This didn't work, any other ideas?

Click to expand...

Are you aware that the fluid level in an automatic transmission MUST BE CHECKED WITH THE ENGINE RUNNING and the transmission in Park or Neutral (some early Chrysler a/t's must be in NEUTRAL since the a/t pump didn't work in Park)?

With the a/t 'cold' the fluid will be near the 'add' mark on the a/t dipstick and near the 'full' mark when the a/t fluid is warm/hot. The 'add' mark means to add ONLY ONE PINT of a/t fluid. You must also be using a Dextron type a/t fluid in your Chevy (or one that is compatible).

Did you ever 'drop the pan'? If so, what did you find in the bottom of the pan.... any deposits or metal particles? What did the a/t fluid look/smell like? Was it 'red' or 'brownish' colored?

Your 'symptoms' seem to indicate that the a/t fluid level is 'low'.... or that the bands are 'slipping'. If the fluid levels were checked with the engine OFF, they would have probably indicated a FULL (if not OVER-FULL), but when you started the engine and the a/t fluid started circulating the fluid levels would have been about a quart or more 'low'. If driven this way for any period of time you would have most likely 'burned' the clutch plates/bands due to 'low fluid levels'.

Had you done any HEAVY TOWING or PULLING previously?

Slug-Gunner

slug gunner

A/t fluid levels were checked properly. Put brand new transmission in about 4 yrs ago. Don't think I ever even pulled a little duck boat about 5 times. Not heavy at all. Truck sat for about six months, when parked it ran fine. Now this is what I have, reverse and no forward. Haven't pulled the pan yet. Going to this weekend unless I hear any other alternatives.

slug gunner

meant to say pulled a little duck boat

Pulling the pan won't tell you much unless you know what to 'look for'. For one, check the transmission fluid color and smell (dark red/brownish color or smells 'burnt' indicates a possible problem/overheating).... but this can be checked using the a/t dipstick and a white towel. Look in the bottom of the pan for sludge or metal deposits.... a sign of major problems if the a/t is relatively new (rebuilt) as you state. Once you get the pan off and the a/t fluid stops dripping a little, carefully pull the a/t filter off (making sure that it was properly seated in the 0-ring pickup tube). If it isn't/wasn't, then that may be your problem since it wouldn't properly pickup and circulate a/t fluid properly. It should be a 'snug' fit in the O-ring to seal properly. Other than that, there isn't much you can check yourself by dropping the pan (unless you're really familiar with the internal workings of an a/t).

You will find it a little less 'messy' to drop the a/t pan if you first pull as much fluid as you can from the filler tube using a gear lube extractor pump and a long vacuum hose stuck down the filler tube to the bottom of the pan. You may have to wiggle it a little to get it past the lip on the a/t filter. Pump it into a clean container for disposal or reuse later.... you should get about a gallon out this way and there will only be about 1/2" left in the bottom of the pan when you drop it. This makes it much simpler to drop the a/t pan without getting a/t fluid all over you and the area under the vehicle. Placing a 'drip pan' under the a/t will catch almost all of the a/t fluid that drips from the filter and a/t body once the pan is removed - making 'clean-up' much easier.

I recommend using only a rubber/neoprene type a/t gasket when you replace the pan and tighten the pan bolts only 'hand tight', using a nutdriver if possible. Tighten all pan bolts progessively and evenly to obtain the best pan-body seal. Too many people have a habit of overtightening pan and valve cover bolts, thus distorting or splitting the gasket (if cork is used). Using a 'high-tack' adhesive on ONLY THE PAN SIDE of the a/t pan gasket will hold it in place for you when reinstalling the pan. Putting RTV on the pan bolt threads will help prevent any seapage around the bolt threads on any bolts that may go thru the a/t body into fluid areas.

Although it probably isn't an issue, pull the vacuum hose off the modulator valve mounted on the side of the a/t and make sure there isn't any a/t fluid in the hose. If there is, the modulator diaphragm is ruptured and the modulator needs to be replaced. The modulator valve controls the shift points based on engine load (manifold vacuum).

Hope this helps.

Slug-Gunner

The additive was only to cure a hard clutch seal, if the trans has a good rev. and doesn't delay, It should go forward if the internals were good, regardless of fluid level. If it pulls forward in manual low and not drive suspect a broke rear sprag. if no forward at all, manual low or drive but has a good rev. with no delay, pull it out. 350 has no bands except for a 2nd kickdown band. uses only the foward clutch and sprag for first D position. uses the low-rev. clutch for manual low and foward for manual low. if you still want to question fluid level, dump a couple quarts in to overfill, if it moves, good deal. if you must pull the pan, the only thing that will hinder drive is the nut that holds the rooster comb on the internal linkage, it will come loose and cause problems, but most of the times locating park will be a issue also. if you pull the pan, don't worry about looking for a O-ring on the filter, 350's use a paper gasket, and if it doesn't seal you want know it, because the fluid level is higher that the gasket.