2000 Limited V6 4WD Auto Noise on deceleration
I was hoping to start my own thread and hopefully get some responses but I am not able to as I do not have any posts. I am fairly mechanically inclined and have been involved with other car enthusiast forums. I have a 2000 Limited V6 4WD (198k miles) that is making an odd whining noise on deceleration.
The noise is somewhere between a screech and a whine and is dependent on load and rpm. It occurs once I let off the gas and changes sound a bit as the RPM's drop. Under load (acceleration), the noise is muted as far as I can tell. Once I let off the gas, I immediately hear it again. When I first run the truck in the morning, it does not seem to happen until I get out of second gear. Once it hits 3rd once, it seems to happen on each deceleration (all gears). It is particularly audible when the truck is holding gears longer while warming. It seems to be coming from directly under the truck and I believe the transmission. Everything feels and shifts fine including 4WD. Fluids have been changed and did not show signs of burning or contamination. I do not have a place to work on it and have not been able to drop the pan/check the screen.
When the noise started last year, I figured the transmission was on the way out so let it be but be prepared. It has now been about a year and 10k miles. It is especially prevalent in temperatures below 50ish degrees and was not very noticeable in summer temperatures (if at all). It decreases slowly as the truck warms and used to go away almost entirely but has gotten progressively louder. It still quiets a bit as it warms up (10-15 mins of driving). Therefore, I do not think it is dependent on coolant temperature and suspect it is from the transmission so is muted when the ATF warms. It does not have a "humming" noise like wheel bearings do when they go bad nor does it have a knock like when a rod bearing lets go.
Right after I bought it last December, I started it to drive to the next state over. I luckily walked around it since it was new to me and heard a gurgling noise. Under the truck, transmission fluid shot everywhere. Instead of the pink milkshake of death, the fitting from the transmission cooler broke off of the radiator and spit the fluid everywhere. The truck was shut down immediately and repaired properly (new OEM rad and fluid). I did check the transmission fluid a few days before that and it was not low. I do not believe the tranny was run significantly low for any length of time. A funny little excerpt from this story.... Imagine a Honda S2000 driving 2 hours with a truck radiator in the passenger seat in December with no choice but to ride top down. I had moreso imagined the 4runner fetching parts for the car instead of the other way around.
I felt like I was writing a riddle of sorts while typing this but I was hoping maybe somebody experienced something similar or had some ideas. I'd like to be able to drive the truck without worrying but it has certainly been bothering me. I was hoping to describe it without entering my suspicions of it being transmission to get some objective views. It doesn't happen in park or neutral and comes from directly underneath the center of the car. I do think that is the root of the problem. Anyone know of a good 4runner mechanic in the Baltimore area? I will try the regional forum when I am allowed. I would appreciate any experience based input to this riddle...
