Lost all gears while driving

[Mr-Jack]

New to this site but not GM forums in general...I recently retired from the military and now work in construction. I've been an aircraft mechanic for 20 years. I have 8 years experience as a diesel mechanic, and I've been a gear head all my life...one of my main areas of expertise are "NOT" automatic transmissions. I can replace, modify valve bodies, flush, and other minor maintenance, but have not rebuilt an automatic transmission before. (Manual transmissions are a different story).

So...coming home from the DOL and was coasting for a little bit and when I went to accelerate, had power, but lost all gears and just hi-revved. wouldn't go in any forward or reverse gears. Tried selecting 4wH/L and nothing. had to have my wife pull me home with my 1 ton.

The truck I'm referring to is an 01 2500hd Silverado CCLB 4x4. 6.0 w/4l80e

A little history, a year and a half ago my wife overheated the tranny and I had to replace it. Found a salvage yard transmission for a reasonable price and threw it in over a weekend and everything worked fine...until now.

It wasn't slipping or anything up until this newer transmission took a dump...just gave up. I tried letting it sit overnight and start it up to pull it in the shop, but that's not happening...it won't budge. On that same note, when you start the truck now and put it in gear, it makes a grinding noise...that grinding noise gets worse when you put it in neutral or park. Also...it holds in park so fairly certain the transfer case isn't the problem. Once it warms up here, I'll pull it into the shop and try a few things to see if I can save a grand or so on a new remanufactured tranny.

My plans are to pull the pan and filter...Inspect that, flush the cooler/radiator/lines out...I guess in that process, I can eliminate if the pump went bad or not. Other than that and pulling the case apart to see what let loose...do any of y'all have any suggestions?

Thanks in advance for suggestions on this matter. (I attached a picture of my 01 next to my 67 just for fun).

Jack

 

[Sparky]

4L80 is pretty sturdy usually.

I'm assuming you've checked the basics like fluid level, condition, etc? Does it smell funny at all?

Aside from that, you're on track for what I'd be doing, checking it for pump failure etc. But nasty noises makes me suspect something blew apart.

 

[Mr-Jack]

Fluid level was fine...didn't smell burnt or anything...light sediment in it...that's because I didn't flush out the lines when I replaced the transmission...oops LOL.

I hope if anything blew apart, it's the pump...I have a spare pump in good working condition sitting in the shop.

 

[Mooseman]

I know my 4L60e kinda died like that. I still moved bit lost reverse and would grind all gears. Guessing it was the sunshell that broke.

Drop the pan and see if any metal in there. If there is, I think it's done.

 

[Mr-Jack]

I will just as soon as the weather breaks and I can get it in the shop. Got 4 more inches of snow since I originally posted.

The truck is a 3/4 ton and my 1 ton can't get traction going backwards uphill in ice and snow... and my tractor isn't big enough to push it

 

[mrrsm]

This link is for an earlier model truck...but it shares the 4L80E Transmission and many of the symptoms there are quite similar to what you are dealing with. Are you close to any of our members who possess a GM Clone Tech2 ? If so and you can get someone to pitch in...this linked information explains that the Primary Diagnostics might be easier to perform with the "Official GM" Scanner and more than likely you will find something damaged that is electrical rather than mechanical (we hope) that might be the cause of the sudden loss of the powertrain. As you are well aware ...the 4L80E is a ridiculously robust transmission for an automatic... and in the absence of you trying to pull a wheel stand while towing a Freight Train... merely driving normally does not seem like enough exertion to have the guts go out all of a sudden. I hope this is helpful... Thank You For Your Service... and Welcome Home, Brother:

http://www.gmtruckclub.com/forum/threads/2000-silverado-2500-4l80e-problem.800090/