1997 silverado trans issue...

[KidCougar]

im just looking for some input or help.My dad has a 1997 chevy silverado 1500 5.7L vortec and its rwd NOT 4WD.It has 189,000 miles and has always been kept up.For the past 3 years it seems the tranmission drops when the truck comes to a complete stop or when it goes only from 1st into 2nd,and sometimes it drops HARD.I think its the transmission but i may be wrong,when the truck gets truned off for over 2min it wont drop hard into gear for another hour atleast.It also doesnt do it rite away it only does it after 30min atleast of driving.Just last month we had the entire rear differential rebuilt to stop the rear end whine and we hoped it would stop the drop but it didnt..ANY Suggestions? Could it be a sensor or maby a bad ecu?

[BR3W CITY]

When you says "drops" what do you mean. Like it goes into gear with a very abrupt *clunk*? First thing that comes to mind is u joints. Have someone watch under the car, and go from Neutral to Drive. You may be able to tell if the clunk is from excessive play in a worn out joint. Also check the carrier bearing if it is an extended cab truck.

As far as internal tranny stuff, I suck in that department.

[KidCougar]

exactly, it makes a hard CLUNK in the rear.I thought maby Ujoints also since my cougar rite now is having an issue with that.And yes it is an ext cab, i will research what the carrier bearing is and where it is.And on sunday ille crwal under there and check the Ujoints like you said.But why would shutting off the truck stop it? maby just luck of the draw? Is there a shift sensor maby i could clean/check..Its a nice truck and its pretty clean so i wanna help my pops keep it that way..

[BAD LS1]

Try cleaning the MAF, these older PCM's use the MAF to help tune the trans line pressure. It sometimes could result in harsh up/downshifts if the MAF is less than perfect. You will need to disassemble the MAF body to clean it correctly, use rubbing alky on a q-tip to GENTLY clean the 5 o' clock shadow off the 3 crosshairs and spray out any build up out of the honeycomb airflow straightener screen and reassemble making sure you point the arrow twoard the engine! Otherwise maybe use the special GM propshaft lube on the trans output shaft splines where the DS yoke slides in, that has been a source for clunks even with 99+ GMT800's.

[KidCougar]

i actually tried cleaning the mafs but it didnt help,it also has a full tuneup recently...thanks for all this input guys, ima try it all untill i fix this problem.

[BAD LS1]

If you dont clean it properly, it wont do anything, thats why i gave the detail on how to do it so it will ensure its clean.

[KidCougar]

i will dissasemble it and try that, now should i use mafs cleaner to blast the wires with,i herd that using a qtip can sometimes leave tiny bits of fuzz that collect contaminates...

[Waver]

Next thread that gets posted up: How do you put back together a MAF?

Honestly, I am willing to bet it is the U-Joints.

[KidCougar]

well, im going to try it all..When i inspect the Ujoints can anyone tell me what exactly i should be checking for...

[Anakonda69]

it's a 4l60e. it's crap. lol

[BR3W CITY]

Your just checking to see if the joints have play in them, the shaft will have a lot of slop back and forth.