ol' burb got trans issues

[heffalump]

Alright I need a few opinions on this problem..
Recently the trans in my suburban has started holding in gear longer than it should, especially going from second into third. Around about the same time I noticed a vibration/roaring that starts around 55-60. Oddly, it stops as soon as you let off the gas and starts again as soon as you give it throttle. Also the torque converter whines like crazy when first started when cold but, stops when it warms up.. I know I've got multiple issues but have narrowed it down ( I think) to the trans but I'm not sure what the exact problem is.. I'm a decent backyard mechanic but im not a transmission tech. Any advice, experiences, opinions, pointing, etc. would help.

 

[89Suburban]

Could be the torque converter clutch taking a **** and slipping. That's what happened to mine. Un-plug it from the transmission and see if it stops. It's the plug that plugs in right behind where the shifter linkage is on the driver's side above the pan.

 

[heffalump]

Took a look around the engine bay and the rubber hose on the metal line Goin to the modulator valve was dry rotted. Replaced it and it seems like everything is good now. Shifts fine, and the vibrating and roaring seems gone also.. could that one line cause all that drama??

 

[89Suburban]

Is this a 700R4 we are talking about?

 

[heffalump]

No its a turbo 400. Tried the plug trick too..

 

[bucket]

Beats me about the noises, but a bad vacuum line can sure cause late shifting.

 

[heffalump]

Fairly certain the noise and vibration is in the torque converter. Just glad the whole trans isn't toast, finding a 400 around here isn't the easiest thing especially one worth anything. I found a few here and there but they all needed rebuild or looked they've been at the bottom of a lake for the last 20 years. The fluid looks good, still nice and red. Plan is to go ahead and do some preventative maintenance - new converter, filter and fluid, and might as well replace the front seal while I'm at it.

 

[heffalump]

As much as I hate it being down I'm not in a real big hurry to fix it for one reason...

This is what I'm driving till I get the burb Goin again..

 

[89Suburban]

As much as I hate it being down I'm not in a real big hurry to fix it for one reason...

This is what I'm driving till I get the burb Goin again..

Cool toy!

 

[heffalump]

Wish it was mine... borrowing it from my dad for a while.. and no he won't sell it to me, been trying for years.