I rebuilt the 4L70E with one of Dana's kits and a Circle D triple disc converter a couple of years ago and have put 27k miles on it. I don't beat the snot out of it everyday, but I'm not afraid to.

My wife was driving the 2006 TBSS yesterday evening in rush hour stop-and-go traffic when the car stopped moving forward. Whatever gear she selected the engine just free revved. She did say that at first it slightly moved forward with a ton or RPM, but then it stopped entirely right after that. From what I've searched it could be a broken pump rotor or the torque converter failed.

How can I know without taking the transmission out which of the two failed?

What would cause the pump rotor to fail after 27k miles? I would think that it would fail pretty quickly if I made a mistake installing it or not checking for proper clearance, or it would fail after a ton more miles due to it being old and worn out.

 

First would be a real determination of cause, Remove a cooler line or put a guage on it and see if you have any presure , If not its the pump. I ASSUME no REV ether os course .
But yes if you have a vey near excessive clearance it can thought any of several methods break way down he road, FLEX PLATE , THRUST BREARING changes are examples.
Also low fluid and sucking air can cause the slide to vibrate rapidly and shatter the pump.
But first to do is determine if you have presure, If you do Could be converter-input shaft or drum .

 

Thank you for the advice.

Fluid level is at the "C" of "Check" on the dipstick with the engine off. I wanted to start it, but the battery was too drained after my wife, kids and their friends were listening to the radio waiting on the tow truck.

Fluid also is dark and smells very bad. Now this makes me wonder if I did not do something right while building it. The hottest it ever got was around 210 because the torque converter was not locking up (cracked solenoid that was quickly replaced and has worked great ever since).

I have a 4L60E core from a 2003 or 2004 truck. From what I've read, i can rebuild this one and put it in as long as I turn off the ISS in the tune. Last time I went through this transmission I tied up my neighbor's lift for too long, so I would rather avoid that. I was going to use that transmission for my C10 LS swap. Is this a stupid approach? Both vehicles are 2WD.

 

Yes you can turn off the ISS on the 2006 I was just looking at a tune HP that year and it seems to be only a diagnostic tooL That year, Later years however though I have not dug deeply yet while you can still turn it off may have unusal lockup activity as I am told the PCM uses it to determine allowed converter slip VIA PWM and no signal even with code turned off can result in overly harsh TCC engagement . Though I have not personally verified this ans I am not a TUNER. though I see no reason you could not copy all the tables to do with TCC from a pre 2007 unit to fix this also.

 

Turning off the ISS in the tune is a nightmare I would not recommend to anyone.
Especially on a 2006 (somewhat a 1 year Operating system setup)

Just because the drop down option is there in HPT doesn't mean it works right.

I have tried this as have a couple other guys that run transmission shops and we've all been haunted by weird issues.
Codes, shift timing, herky jerky action, etc
It isn't always the same but it seems that without fail every time I've tried there has been at least SOME issue

Always resolved by just putting an ISS model back in

 

Fair enough, HPT is probably lacking some parameters to make it complete.

Now, I don't even know if this is possible as i dont have much experience with the E40 and T42 combos, would changing the T42 OS to a non-ISS work? Like from a 2006 GTO?

Downtime on the lift is really the issue here, i can't expect to have the vehicle on my neighbor's lift again for so long. What parts would I need to add an ISS to a 2003 3CHD 4L60E? I know that the input shaft with the reluctor is needed and that the wiring harness is different as well.

 

You will also need to change the stator support.

 

To swap a Non ISS to an ISS
You need:
pump stator half with hole for the sensor and the correct stator (oil hole positioning changes)
Reluctor Style Input Shaft
Internal Wiring Harness

Swapping OS can get tricky especially with the E40
You could try but just be forewarned you might have a headache in front of you.

In reality, If you are good about ordering the right parts you'll need, there's no reason you can't remove, rebuild, and install that unit in one good weekend

 

You would need the pump assembly (some do mix match front and backs, I have seen it done on units I have torn down as cores . Never done it but they had been running a while so guess it worked. And another method I saw recently had been done. Someone just chucked pump in a lathe and cut the groove for the rubber sealing oring so late pump coud be used with early case. Saw some guy on youtube do that , simple enough if you have access to a lathe. And of couse use the ISS input shaft.
As far as the tuning changes as I mentioned earlier I am no tuner and in fact new to HP so cannot give the advice other more experienced can . My information in this area is second hand. I have hear some say and post over the years they had no issue with it 2006 2007 just tuning it out but again not first hand, Now later models I have heard of issues with lockup. Better to take advice here from others with first hand experince as I said NOT A TUNER HERE or at best TUNER IN LEARNING.

This all if time is really pushed and just cant make time to remove build and install .

As is said ANYTHING CAN BE DONE . BUT SHOULD IT?

 

I'm not aware of a T42 TCM having an option for a non-ISS OS. (A 2006 GTO still uses a PCM. CORRECTION: The 2005 and 2006 does indeed use the E40 ECM ).
The TCM simply requires the ISS signal for its software to work correctly; it has nothing to do with HPT limitations.
As @MaroonMonster mentioned, few if any have ever gotten it to work perfectly without ISS.
A proper 4L60E with ISS should be easy and inexpensive to find. Taking even a free non-ISS and converting requires way more complexity, time and parts than its worth. For example, swapping stator supports has frustrated many people who don't have the right tools. I know I used a hydraulic press, alignment is critical and just getting the bolts out can be a challenge.

 

The 2006 GTO does have a T42:

I did do some more searching and it looks like just turning off the ISS option will lead to unwanted transmission behavior. I also talked to my neighbor and he does not mind if I tie up his lift for 2-3 weeks. Ill need to get into the transmission and see what the extent of the damage is, and also I think it would be a good idea to send the converter back to Circle D to have it inspected and repaired as the fluid is dark and it smells.

Assuming that only the pump rotor broke, what other components should I replace while the transmission is apart?

 

You will not know till you get it apart. Take photos of what you see that might be of question. That way I can let you know what you might need here.
We'll go from there.

 

If this is an AWD trailblazer SS, i would first inspect the AWD intermediate axle coupler on the pass side of the oil pan. This is known to strip out and cause a similar issue. Due to the AWD TBSS transfer case being a helical gear style, SOME resistance is needed to distribute torque, when the coupler fails and load on the right front axle goes to zero, 100% of torque is distributed to that corner.

I have had a handful of tbss brought to me over the years that "need a trans" only to find that coupler stripped on the awd units.

This is a picture of the intermediate axle on my personal tbss i tore down at 85K and the axle splines are mostly stripped.

 

Will do, thanks Dana!

I really wish it were that easy, but 2WD here.

 

doesn't the fluid level CHANGE on the dipstick if the engine is running or not? If so, you would think if the pump rotor is broke, the level would stay the same when running or not?

 

and btw, I DOUBT its the convertor. If it was an FTI budget convertor, I would put my money on that... but circle D, nah.... I doubt it. Fluid was probably low and shocked the rotor. Fluid level should be higher when the engine is off and if its showing "check" now (with engine off)...... well...you know the rest....

the unfortunate thing is the pump is probably going to be scarred and damaged because of the rotor. And youll likely have had chunks of metal go into the convertor, so You'll need to send it off. But do yourself a favor while its apart. The thing I preach about pressing the input shaft out and loctiting it back in, do it. Do not skip this step. That shaft will leak and burn up your 3-4.

You'll need to get some loctite shaft retainer. I use 638. You'll need to slide a reaction shaft over the input shaft to support the drum, if you do not, you'll break the aluminum drum. Then youll need to support the hun on the other side when pressing back in. If you need more direction with this, just holler.

 

Glad you posted this super simple method of determining if the pump is shot. It was mentioned here many years ago, maybe by you.
I would expect the fluid level to go down by at least one inch on the dipstick when the engine starts and the pump is good.

 

yea if the engine is shut off for a little while, fluid from the converter, a little from the valve body and clutches, drains back into the pan. It’ll show a bit overfilled when off, and normal level when running. If it shows overfilled when running, the pump is bad. HOWEVER, the more you run it with a damaged pump, the more damage will happen to the pump…..but it’s probably shot at that point anyway.


being that his level was low when he checked it while not running, makes me believe the level was low and got damaged because of it, like someone above had mentioned.

 

Running a 4l60e low on oil can be super hard on the pump
Those vane style pumps do not deal with being cavitated well at all
Combine that with the slide that can move and you've got a recipe for a broken rotor.

Good luck to OP

 

Can't go out and try it since it's snowing and my wide ran the battery down with the hazards and listening to the radio while waiting.

When I looked at the fluid the next day, the level was just by the "C" in "CHECK", so above the "HOT" range, like in the photo below (not my dipstick, closest example I could find):


I will charge up the battery and see if the level drops with the engine running once the weather improves.