Hey all
I put this out to different F150 forums, but haven’t received much in response. I figured I’d post here too.
I have a 1995 F150 XLT with a 5.0 and 4R70W.
I rebuilt the 4R70W about 3 weeks ago (forward clutch pack was burnt out) and it has been driving perfectly fine. [Side note: flex plate was not removed during the rebuild.]
I noticed a few days ago that there was a noise whenever I revved the engine in park or in neutral. I recharged the AC last week and the noise wasn’t present when I was revving the engine in park.
Drive and Reverse are fine. It only happens when the transmission is not in gear. Transmission fluid level is good.
Here is a video of the sound: https://streamable.com/mho7p
Any ideas? As far as I can tell, it doesn’t affect driving performance, and doesn’t happen at idle.
—Day 2—
I used a mechanic stethoscope and seem to have isolated the issue to the bell housing where the flex plate sits. If it were something in that area, why would the noise go away in gear?
I also noticed that the transmission vibrates when the noise occurs, but I only hear it on the stethoscope around the bell housing.
Some theories were loose flex plate bolts or a cracked flex plate.
—Day 3—
I took the inspection plate off the bell housing and checked the flex plate to torque converter bolts. They’re nice and tight, and there isn’t any warping in the flex plate. I started the truck and noticed the noise wasn’t coming from the inspection hole.
I used my stethoscope again and seem to have isolated the issue to the starter. It seems to be coming from where the starter teeth contact the flex plate.
This is what the starter looks like: http://imgur.com/6OZvFju
I took the starter to the store and they bench tested it for me. It’s engaging and disengaging perfectly fine.
—Theory—
I wonder if there is a short somewhere in the system causing it to remain engaged or partially engaged. Is this possible? I thought the starter solenoid was simply an on/off operation?
Could the reason why the noise isn’t present in gear be because the neutral safety switch cuts power to the starter?
I’m going to run a multimeter to the starter solenoid and solenoid switch on the fender this afternoon.
What do you guys think?