4L60E Auto Trans question

Sharps40

Old Mossy Horns
So....trans mechanics.

02 Blazer ZR2 4WD 4.3L V6 with 4L60E trans.

Runs great. 167000 miles. Never off road, always babied.

Changed Wix trans Filter and 5 qt top off at 150000 miles. (Don't know history before beyond, owner bought it at the dealer she worked for).

Fluid was red but dark and did not smell burnt.

Pan had the normal/expected film of metal mud on the magnet and no chunks of anything. Old filter looked great too...overall, inside looked great and it shifted great though a bit slow to pump up into reverse when you shift from D to R.

After the change, same same, perfect function, slow going to reverse.

This week: Trans is full, fluid clear and no burnt smell but......a bit of a hesitation and a tiny bump when sitting in drive and pressing the accelerator. No other bumps jerks grinds hesitations shudders or belching of fluid....i.e. it works great but for the wind up to a bump in D when pressing the gas.

Thoughts? (Wondering if I should be saving up for a rebuild/replacement.....ain't had but one auto trans in my life so, no experience with them beyond knowing that a TCI 350 Street Fighter is the berries behind a 300 hp 327 in a 62 impala)
 
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Sharps40

Old Mossy Horns
It feels like its sitting in 2nd at a stop then as the rpms slightly advance, it finds first and off we go!
 

JimmyC

Button Buck
Try manually putting into low gear and shift it your self and see what it does that way. Cloud have a price of trash stuck in a valve somewhere.
 

nccatfisher

Old Mossy Horns
Contributor
If it doesn't have any burnt smell and no abnormal clutch debris in the pan it all points to valve body issues.
 

Sharps40

Old Mossy Horns
Prolly right. Be good to put seals in xfer case and engine rear main at the same time. Might need to start saving a $ or 3
 

bigten

Old Mossy Horns
Contributor
Rich, I'm NOT normally a proponent of canned fixes, but the best additive I've found over the years for transmissions is Trans X
It can be found in any parts store as well as many Wal Marts. It frees sticky valves and softens seals without swelling them. I'd try a quart in your case.
 
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Eric Revo

Old Mossy Horns
Contributor
I was gonna post something along those lines as well...I've used the Lucas brand transmission additive and it worked great for a car with over 300,000 on the transmission. Sometimes the new fluid doesn't provide enough grab in older transmissions, the additive packages will provide that needed grab sometimes.
 

Sharps40

Old Mossy Horns
Copy. Just tryin to see if I am on a short or long road to loosing a gear. It's intermittent now so I'll keep driving. Kinda went in figgerin it'd be a rebuild. No shame though, 15 years and 167000 miles. Mebby coax another hunting season out of it and put in to a shop over Christmas.

I'm guessing its a worn clutch pack issue for reverse . And a pump/pressure issue in drive since there is no flaw in low gear forward takeoff when the shifter is in low or when in drive and the rpms are over 550 with the engine still warming up.

Trans is prolly tired. Reckon I'll run it some more and shop in the meantime since Really like the truck....prolly go with it and drop in a pint or qt of good bandaid in the interim.
 
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JoeR

Eight Pointer
.i.e. it works great but for the wind up to a bump in D when pressing the gas.

If you're saying that you are sitting in Drive, and get a slip-bump when you press the gas, then this is the most worrisome symptom. For the delayed Reverse, I'd first suspect hard seals on the low/rev piston. Same as the TH350 you are familiar with. Most likely not a big deal.
I'd want to diagnose the slip-bump as best I could before disassembly. On the 4L60E, there are a couple of things that are likely suspects.

Low pump pressure, causing the input clutch to slip at idle. Touching the gas bumps the pressure and engages the clutch. This could cause slow reverse engagement too. Thankfully it's easy to check.

As already suggested, valve body troubles. If i was building it, I'd put a quality reman valve body in it. The TCC PWM valve is due to start sticking in it anyway (google P1870 Code on this trans).

If you already have some trans knowledge and want to build it, yank the trans and make a trip to Stokesdale. I'll give you a hand. Shoot me a PM if interested.

Joe
 
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Sharps40

Old Mossy Horns
Slip bump is exactly the symptom....

Thanks joe, for the offer of help, but I have avoided transmissions all my life. Don't make any sense to me how they work, everything spinning and going from front to back to front again...and, For now, no funds. When I was young, I raised a 62 impala up high enough to pull out the worn th350 on my chest and man handled a new TCI StreetFighter off my chest and up into place. It was a cuss fest.

I'll have to nurse this along and then drop it at a shop for a reman install on the old credit card....hopefully not till months from now! If there is money a 5.7L conversion too....since I'm already getting v8 gas mileage, it'd be nice to have an 8 but the likely scenario in the near future is a simple trans swap as even that'll tax the budget + its already higher wider and not sure I want a 2" body lift just to be able to retain AC with the V8 swap....

No codes at all on this truck, I have a code reader and its all clear.

As an update, dropped in a 10 oz can of lubeguard platinum as that's about what the dipstick said we had room for. 150 miles later.....trans has a different feel. Best I can describe it is, not loose and, it moves forward a bit faster at idle. As for the rev bump.....only did it once since pouring in a can o bandaids.

About the only other benefit of the liquid bandaid that I can surmise is the obsure feeling that my testosterone may have increased by 17%, so smashing the gas harder with my new manly powerful foot if only to feel it shift and convince myself the lubeguard did a miracle, I'll drive her till she breaks!

Thanks all!

If ya see us on the side of the road.....we need a ride. :)
 
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45/70 hunter

Old Mossy Horns
Contributor
Rich, I'm normally a proponent of canned fixes, but the best additive I've found over the years for transmissions is Trans X
It can be found in any parts store as well as many Wal Marts. It frees sticky valves and softens seals without swelling them. I'd try a quart in your case.

^^^Second this!!!^^^ I put it in an old Dodge Dakota that I was sure needed a rebuild at around 180k ... she's still rolling, just passed 200k.
 

Markfromflorida

Eight Pointer
I had a 98 ZR2, great little truck with lots of pep.... Tranny went out around 150k miles...but I did abuse it a little off-roading.
 

bigten

Old Mossy Horns
Contributor
Shoot, I just realized I left the word "not" absent in my post. Went back and added it in....
 
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