4l60E transmission help

My Wife's Trailblazer is having a couple of possibly related issues. When you put it in drive it takes a solid two seconds before it engages. It goes into reverse normally. It's also started to suffer from torque convertor shudder. It typically happens at steady state cruising around 55 mph. Lifting off or pushing on the gas stops it as does tapping the brakes.

I was hoping to replace this truck in the next year so I don't really want to drop money on a new transmission. What does the hive say? Drive it until it dies, try a miracle in a can product or just pony up for a rebuild?

When was the transmission fluid last replaced? What's the current condition (and color) of the fluid?

I would mask the symptoms and get rid of it right now.

Does the delayed engagement happen even after the truck has warmed up or only when cold?

In reply to dj06482: Sorry I missed mentioning this. I flushed the tranny and put a new filter in yesterday. Filled it with Mobil 1 Dextron VI. The fluid was little dark but not bad.

Does the TPS have more than 150k miles?

Trailblazers are all drive by wire.

Drive it a bit and see how it is with the new fluid/filter. If you still have the oil filter, set it up on its side for a day or two to drain out, then use some dikes to cut the sides off and open it up to look for metal shiny bits. If you've never opened one up before, they're kinda neat inside, all the debris will be inside the "sandwich" so you have to open it up.

Maybe it's more like pita bread than a sandwich. Now i'm hungry.

In reply to Vigo: It happens warm and cold. No change.

Most 4L60es don't live much past 100-120,000 miles.

Could be a big leak in the forward clutch apply piston or some part of its hydraulic circuit. Does it engage right away if you shift straight to manual low/1 Position?

Suck out 24oz of fluid and replace it with Lucas trans fix, then hope and have cash set aside for the possible rebuild.

In reply to Appleseed:

My '96 C1500 has 257k on the original transmission.

racerfink wrote: In reply to Appleseed: My '96 C1500 has 257k on the original transmission.

Wife's 4x4 Jimmy had 170k on it when we drove it 2300 miles to give it to her brother. Original trans.

Brother-in-law's Blazer has 250k on it, original trans.

My brother's 1/2 ton full size GM truck with 4.3 Vortec did need a new transmission. At 280,000. After towing several cars, campers, and other trailers with it.

Wife's Suburban is on the original 700R4 (non-electronically controlled 4L60E, basically), with 179,000.

YMMV

I'm not sure why the delay in engagement. The 700R4 in my wife's Suburban engages Reverse in about 1/2 a second when shifting from Park. When going from R to D, or P to D, I can count "One thousand one" before I get that little clunk to let me know it's in gear. Some googling brought up guys having to wait 4 or 5 seconds, so I feel a bit lucky now. General consensus seems to be, change the fluid and filter, drive it for a few hundred miles, and see if that helps.

I have had pretty good luck with that Lucas trans fix in a bottle, too. On the trans on my Mercedes 300TD it cured a slight leak and firmed shifts up noticeably.

My recent 4L60e woes turned out to be a bad TPS and crappy spark plug wires. The wires caused the shudder (at a very specific 50-60 mph in OD, cured by revving it up a bit and putting in in D. The TPS just sent bad info and made everything bad past 1/2 throttle. The 'e' part of 4L60e means that everything is controlled by a sensor so I'd look at that first.

(234,000 miles in a Suburban)

I picked up some Lucas transmission mechanic in a bottle stuff. I'll add it tonight. I think look into the cost of a TPS and throw one of those at it too. The plugs and coils have been changed recently. It isn't throwing any codes but it's still pretty subtle.

Just FYI, the fact that something is new doesn't mean it's good. Mine had no codes but when I popped the hood one night I could see sparks arcing off the two year old plug wires.

In reply to KyAllroad: Oh I know all about having new parts fail. I'm just trying to work from cheapest first. The TPS is unfortunately part of the throttle by wire body assembly and has to be replaced as a unit. I'll try cleaning the connector and throttle body.

Dad's original 4L60E lasted 180k miles. Had it rebuilt, it lasted another 21k miles before the sun gear exploded (quite literally). Did have some issues with a pair of back to back bad rebuilds (NEVER get one from Movarus) but is back on hte road and rocking again at 220k.

As to the original issue, the 700R4 in the old 9C1 I had did this same thing from the day I bought it with 109k. Put 20k miles on it before I lost 2/4th. That one lasted until I sold it at 209k.

Wayslow wrote: In reply to KyAllroad: Oh I know all about having new parts fail. I'm just trying to work from cheapest first. The TPS is unfortunately part of the throttle by wire body assembly and has to be replaced as a unit. I'll try cleaning the connector and throttle body.

Poor TPS is something that you only have to think about on old drive by cable vehicles with a separate trans controller where the transmission is reactive. On drive by wire, the trans isn't just reacting to what the engine is doing.

Did I miss the part where you tried putting it in manual low to aid in an actual diagnosis? I guess that's sort of implied by "working from cheapest first". Le sigh.

In reply to Vigo:

Sorry. Yes I tried doing that before I posted here. It has delayed engagement in any forward gear.

Ok. Looking at the apply chart for that trans i'm going to guess you have a huge hydraulic leak in the forward clutch circuit and it's possibly dragging down your pressure enough to make your torque converter slip at low engine (pump) rpms. You could acquire a pressure gauge and check that. You could drop the valve body and inspect the separator plate gaskets for signs of leakage and see if the valve body is warped, and then air check the forward clutch circuit in the case. I kind of doubt it's something you want to get into unless you're just curious about automatic transmissions.