Driving the truck down the road, about two miles from the house at around 45 mph when out of nowhere I notice the RPMs shoot up and the speedometer pegging out at 100mph and then bouncing back to around 60mph and then back to 100... No funny noises, jerks, or anything like that. I turn into a driveway to turn around and head back to the house - shift into reverse and the truck doesn't move. I shift back into Drive and still nothing; so I try to put it into park and all you hear is a nasty grinding coming from underneath the truck. No grinding when moving between gears - only when trying to put it into park. You can turn the truck off and put it in park just fine. Crank it back up and take it out of park without any issues, but as soon as you try to go back to park there is the grinding.

Got it towed back to the house (only two miles away so we put it in neutral and pulled it with my other truck) and now I'm waiting to hear from my mechanic.

Any ideas? Time for a full rebuild of the tranny? Truck has always been serviced by dealership or the dealership service manager at his house (good friend of mine). Transmission fluid/filter change done at 85k along with all the regular tune-up stuff (plugs, cop boots, PCV valve, intake cleaning, MAF cleaning, coolant flush, etc.) I had the the rear end fluid changed at 109k, and just had the fuel injectors, forward o2 sensors, and the COPs replaced last weekend. Truck has been running like new without any hint of a problem - purring like a kitten and pulling strong. Truck only has 111k on it now.

 

Anyone? Every time I have ever heard of transmissions going there was bad jerking, noises, grinding, grenading, sudden stops, etc. - mine didn't do any of that...it just stopped pulling while driving.

 

Its very hard to believe this happened IMO, and thats why you arent getting any answers. Your transmission going out would not cause your speedo to fly up to 100mph. Actually, consider this a shot in the wild darkness, but I would guess that you might have a speed sensor or something thats acting up. Maybe horrible U-joints? When my trans went out, it went out slowly. I first lost overdrive, and the truck began to accelerate very sluggishly. After driving it (knowing that trans was going out) for a couple of weeks, it finally got to the point that it would only move around at idle. It was never completely immobile, but trying to accelerate was a lost cause. There was never any grinding, noises, jerks, or any kind of abnormality other than the truck not going anywhere. So what did I do? I drained the oil. The oil was dark brown and smelt burnt. Thats the general sign that the trans is going out, well- if the oil is dark brown or smells burnt you are already too late. You need to check the oil in the trans. If its red and has no smell then you are fine.

 

sounds like you blew up the differential. The wheel speed sensor is on the differential not the transmission. If you popped the diff you could get high MPH readings like that

my guess is probably a spider gear, and it did more damage when it came apart

 

I agree with this. The Speed sensor should be on the very top of the diff. That also better explains the grinding, and all of the other issues the OP was naming.

 

I had a tempo a few years ago that did something really similar. It was a valve body in the tranny that went. Cost $350 instead of $1400 for a rebuild

 

A valve body issue caused the speedo to run out of control???

Darrin

 

id say the torque converter blew up inside. My brother has a dodge that he called me on a couple of years ago, same thing happened to him, moving along and then nothing, no gears at all, grinding when you go to park position, shut it off and it would go into park, start it and no gears, but the grinding came back for park. Towed it to my place, 25 miles, tranny shop came and picked it up and told us when we called on it that the torque converter blew up on the inside. Good luck Bob

 

A torque converter issue caused the speedo to run out of control???

Darrin

 

I am going to tell you that I am (was) completely stumped (because I was thinking grinding instead of the noise a parking pawl makes). Which is why I am not throwing out any wild geese.

This is an odd one.

Darrin

 

This is the most likely idea so far and it does seem to cover all the general complaints. The speedo would run out of control when the speed sensor is on the diff and the mechanical connection in the diff is broken. There would be "grinding" when you try to put it in park with the engine running after it has been put in a gear because the transmission and driveshaft are spinning. It would be like throwing it in park on a vehicle that isn't broken while driving down the road. The parking pawl will make a ratcheting (grinding) noise as it tried to catch the ring gear. And, if the breakage is in the right place, nothing might make any odd noises until you try to put it in park and the parking pawl tries to catch the freely rotating output shaft ring gear.

A broken rear end made total sense to me as soon as the coffee came into effect and I was able to decipher what "grinding" potentially means in this case.

If the above conclusion is correct then the grinding would be more of a ratcheting sound that will match speed with the engine rpm. It won't start until you take the vehicle out of park and put it into any gear and then back into park. And then, it would only happen while in park.

I think Patman03SprCrw nailed it and that isn't the easiest thing to do over the internet.

Darrin

 

If it was the rear diff that was blown then wouldn't the truck be able to move when I put it in 4x4? It did nothing in 4x4 hi or lo.

Rear diff was just inspected/serviced 2k miles ago by the local dealership service manager who does all of my work - said everything looked good.

 

Having thought about it a little more, I am again stumped because I would have thought there would have been a mention of park not holding the vehicle.

As I said earlier, this is an odd one.

The issue with the speedometer doing that likely precludes the transmission because the speedo info comes from that sensor on top the the diff. To include the transmission would mean a multiple failure occurred and usually a serious failure like that would have created at least a minor racket when it happened.

 

I expected it to have made some sort of racket or jerking or something. It was literally cruising at 45-55 mph one second, and the next second i noticed my RPMs were up and then the speedo was pegging off of 100 and then bouncing back down to 50-60 and then back to 100. The lack of anything alerting me to the transmission being out made me immediately think that my alternator had gone out and was causing the gauges to act erratic...so I pulled into a driveway and put it in reverse to head back to the house - thats when i realized it wouldn't move. Tried going forward again - nothing. Then tried putting it in 4x4 - still nothing. When I tried to put it in park is when you could hear the clattering from under the truck - so I put it in neutral and turned the truck off then put it in park.

 

you should have been able to move the truck in 4wd, unless you also have underlying 4x4 engaging issues that you didnt know about until you tried to use it.

Keep us updated once you get it to a shop!