Drive train noise help please

[mississippi]

im gonna try to give as much info i i can and see what you men think the problem is.

i have a 2000 chevy suburban 2500 4x4. here's the deal. when i drive down the road and the transmission has shifted out, at about 1500 rps or so i get a hard/loud vibration. sounds like i run off the road and hit the wake up strips..if i let off the gas it stops and if i give it gas it stops. it happens at the time the engine/transmission has the least load on it (if that makes sense) not going up or down hill, but say on flat road, cruise set and you try up increase speed just by pushing cruise control +. does that make sense??

 

also, when i pull something and the transmission gets to about 190 degrees it starts shifting really hard. does anyone know what is causing these 2 problems?

[Doug_Scott]

For the vibration/noise, try just touching the brake pedal, not enough to apply brakes, but enough to turn brake lights on. If your trans has the lockup converter, that will unlock the converter. It would be best to try that while it is vibrating. It will not prove the converter is the issue, since once the converter unlocks, engine speed will raise about 500-700 rpm, which may take the engine out of the range that the vibration occurs. It may not prove trans is bad, but it can prove it is not bad.

 

When all this fuel injection, on board computers and other high tech crap came out, I was told to not forget the basics. Always check the easy stuff first. Generically that means check plugs, wires, cap, rotor, filters, and fuel, before you start throwing parts at it, hoping something sticks.

[mississippi]

Doug Scott. Thanks for the reply. Tomorrow I'm gonna hold it at the rpm it happens at and lightly touch the brake and see if that make it quit. I bet it does because any slight rpm change it goes away.

Does that mean its a possibility it's the torque converter??

Ill post back the results tomorrow

[mississippi]

ok doug.. drove it this morning. let it shift out.. shifts out as smooth as always. while in 4th, running about 1500 rpm's it starts the hard/loud vibration. i lightly put my foot on the brake pedal while maintaining the rpm and it continues. i graduly push the brake harder and it continues until it shifted down to 3rd. for the next 20 miles. i could not get it to do it. i will add it does it worse when its cold, not as much once everything gets up to temperature

[gmtech4]

have a tech road test it ,,,,unless you can get audio or vidio with the help of a buddy and post back ,,,

 

13 yr old truck and the internet is a hard one to fix ya know

[Doug_Scott]

ok doug.. drove it this morning. let it shift out.. shifts out as smooth as always. while in 4th, running about 1500 rpm's it starts the hard/loud vibration. i lightly put my foot on the brake pedal while maintaining the rpm and it continues. i graduly push the brake harder and it continues until it shifted down to 3rd. for the next 20 miles. i could not get it to do it. i will add it does it worse when its cold, not as much once everything gets up to temperature

 

I had written a long reply last night, but did not press Post. I had asked if you could try using 3 instead of D to see if it happens when limited to 3rd gear.

 

If your truck is like my 2000 GTP, it would not lock up the converter until it was warmed up. I have found that if you are going to have a trans issue due to worn/leaky seals, it would be worse when cold. I think govtech4 is correct, it is time to get a technician to experience it.

[mississippi]

i tried 3rd and yes itll still does it.. once it warmed up it dont do it anymore.. ill take it and let someone listen to it..i just hear these horror stories of folks taking it to places and never getting it fixed the first time and shops just swapping parts until something works. im one of those folks that if it need a transmission.... lets put one in it and be done... i dont like to change part after part and by the time its fixed... i could have put a new one in it ya know?? i was hoping it was something common on a 2000 model that mine just waited 13 years/130,000miles later to do!! LOL when i get the results i'll repost and maybe itll help someone in the future. thanks