700r4 question
 

Just picked up a 1992 rs 305 auto for my son.
Car has 85000 miles and runs very good. I noticed today a slight weird noise when it shifts from 2nd to 3rd today at a slow speed but no noise if your on the power a bit more. So I thought it might be something loose under the car. I went through the entire undercarriage today and everything is tight as it should be. So I sat in it while it was running sitting in my driveway I went through the gears. I slowly shifted it into reverse then neutral then OD then into D all was perfect then when I put it into 2nd I could hear a humming. Not super loud but definetly a humming. Then Input it into 1st and the humming remained. You can clearly hear a difference from D to 2nd back and forth hum no hum hum no hum.

I know this is not normal as I have owned 9 auto 3rd gens and have never heard anything like this.
So my question is: where do I start to look for whats causing the hum/hum noise as it shifts? Or should I just pull the trans and have it rebuilt? Every other function of the trans is perfect. Shift at the correct rpm the tv cable is adjusted correctly the fluid isnt burned and is filled to the correct level. Just dont want my 16 year old stranded . Thanks for any suggestions

Re: 700r4 question
 

What you're hearing sitting still sounds normal to me. Did your 9 others have transmission mods? Does this one? Manual 1 and 2 get a boost in line pressure, so the pump is going to make some noise then. Start the car, pull out on the TV cable and you'll likely hear the same whine. I don't think this is the noise you're seeking.

Re: 700r4 question
 

If the filter is the wrong make (cheap China no name ones), it can be restrictive causing pump whine. Sometimes the filter is not sealing against the orange ring in the front pump tightly and this can pick up air, which can cause pump whine. These problems will show up when manual "1", "2" or reverse is used as the line pressure rises when in those shifter positions. The best filter to use here is the Sealed Power filter. It will have the markings SP, SPX, filtran or microfelt stamped on them.

Re: 700r4 question
 

Thanks for the replys. This weekend my son and I will be changing all the fluids. So Ill pick up one of those filters for the trans and see if that helps.