Well, losing 3rd needless to say isn't good, I guess you have a couple options. You could throw in the towel and spend the $1800 in which I agree isn't a bad deal for an R&R with rebuild...which is likely inevitable. The other option would be to pull the valve body and see if you punched a check ball through the separator plate.
The issue is how much driving has been done with it losing a gear, how much life do you have left IF the separator plate is the cause or your 3rd accumulator which could be the checkball capsule.
The only sign of life I see is before it would go a few hundred yards, now it went a few miles.
How much driving could you do after the filter change in 3rd or even 4th before you realized you didn't have 3rd?
What would be a bummer is the possibility of having life left and not realizing it, but just a few hours of labor to check.
Does the fluid smell burnt? What color is the fluid?
Are you up for removing the valve body to see what's going on? Not hard to do just some drips of tranny fluid on your head and a bunch of bolts.
If that were mine, I would pull the valve body and see what was going on. If you have a worn plate then that could be the problem but odds are not in your favor....worth a look IMO.
This is exactly what I was going to suggest yesterday as well, but deleted the post as I felt it was 'too' long. As gmcman said - you *may* get lucky and find the 2-3 checkball has pushed through the plate (partially or fully). Even if it takes you a full day to get the VB and the separator plate off to check, it's way cheaper than immediately shelling out for the rebuild.
Actually, you may not even need to remove the separator plate, if the checkball is stuck in the plate, or punched through it entirely - you'll see that checkball missing in the VB, and / or sticking in the hole in the plate.
If you get lucky, and that's the case...fix the problem (including a new hardened separator plate), put it back together (make sure you don't mix up the bolts for the VB - they're different lengths!), and you may get a little more life out of her.
If not - you're only out time, fluid (and maybe a filter, depending on how long the current one's been in the trans). You can drive it in 2nd ('2' on the selector) if you need to keep it on the road, until you've got the scratch for the rebuild.
If you do wind up rebuilding...
- Consider getting a hardened sunshell (the 'Beast' shells are the way to go here), and a HD 3-4 clutch pack / steels. Those are two of the three weakest points of the 4L60, which is otherwise considered an excellent auto trans - one of the best ever, from GM or anyone else.
- You'll also want to get a good 2-4 (intermediate) band. I'd stay away from the Kevlar bands - they're really aggressive, and most people who put them in on performance builds tend to regret it, and often have to replace them - plus they don't hold as well (being too hard to grip the input drum, and causing wear on the drum, especially one that's been in-service awhile). The Borg-Warner 'High-Energy' (which I now have) is supposed to be the same one that the dealer sells as a 'performance / heavy-duty' band. Alto also makes a couple of nice bands - very highly rated.
- Replace any plastic accumulator / forward pistons with aluminum ones. Sonnax makes pinless ones, if you want to eliminate a potential wear spot, and increase the holding power a little more before each shift (firmer). The plastic ones tend to form stress cracks where they move back and forth on the pin, and eventually crumble, creating harsh shifts - so
don't reuse them.
- Put a NEW Torque Converter on. NOT a rebuilt one. Yes, it will cost a little more than a rebuild. Just get a new one. Unless you're running the truck really hard all the time, or towing, you can stay with an OEM / equivalent. Otherwise, you could put one in with a slightly higher stall speed - I have a 3200 stall in mine. IIRC, the stock ones in our trucks are 2400-2600.
- Finally, take care of the TCC / PWM issue - by disabling it. The first way is TransGo's shift kit (4L60-SK2 - 'orange box') - they replace that valve with one that converts the PWM to an 'on / off' function, instead of continuously slipping the converter (and wearing the bore in the VB that the valve sits in.) I have this, and it works as advertised.
If your TCC bore is worn, you either need a new VB, or have the Sonnax kit installed - which provides an oversized valve, via reaming the bore. The Sonnax reamer is expensive, so only go this option if your rebuilder already has the reamer, and experience using it - if he has the reamer, he'll probably want to go with the Sonnax option. A lot of people prefer the Sonnax option - but many here have done the TransGo version, and find it works fine / lasts just as long as the Sonnax option.
- Use a good synthetic Dexron VI - Valvoline makes a good one that won't break the bank. Make SURE you put enough in - the owner's / service manuals call for 5 qts for a regular 'pan drop' exchange - but if you have the truck down for a long time, you may have more than that drip out. Be careful - I wasn't, and ruined all the work I had done on my own putting in the shift kit. An expensive lesson, to be sure.
And after the new trans is in - especially if you plan on holding onto the truck - get a good external trans cooler - like a stacked plate, which is the most efficient type. You don't need a huge one - I run one of the smaller Derale coolers, and it keeps the fluid at about 150F - without going through the radiator first. The lower you can keep the fluid temps - the longer the fluid
Yes, this is a lot of info. Hopefully it helps you when it comes time to do your rebuild. Maybe you'll be lucky, and you won't have to rebuild yours.
