700r4 help

[Mr_Random]

Are these slushboxes known for wearing out torque converters quickly? Our suburban is acting a bit squirrelly and making sounds from the tranny/bellhousing area. The transmission was rebuilt about five years ago and we really don't want it to be the source of the problems.

I'll explain a little more if anyone needs the info to help me.

 

[1blackz28]

I wouldnt say torque converters exactly but the 700R4/4L60E are known for failures that require rebuilds. For example I had 3 camaros and 7 transmissions between all of them 2 700R4s and 5 4L60s

 

[Mr_Random]

I wouldnt say torque converters exactly but the 700R4/4L60E are known for failures that require rebuilds. For example I had 3 camaros and 7 transmissions between all of them 2 700R4s and 5 4L60s

Well the main difference is that the 4l60e is completely electronically controlled. They have a complete "lock-up" converter, much like the aw4, but I think the 700r4 has a normal viscous converter, which wears out faster? I don't know... I've only dealt with manual transmissions and I'm only eighteen, so I'm trying to figure this out you know?

I'm hoping the transmission will be rebuilt under warranty, but I'm not sure... Our last one lasted 120K (from 88 to 2003), why would this one go out at only 20k (2003-present)?

 

[5-90]

What year?

The "early" THM700R4 (up to 1985 or so) is known for having a "fatal flaw" - and the primary fix is to install a newer transmission (THM700R4 or 4L60 - the "E" version, as previously mentioned, is electroncally controlled.) However, I believe this fatal flaw is something in the valve body, and not the torque converter. I do know it can't be reliably repaired for any length of time.

NB: The THM700R4 is first is the series of THM700R4, 4L60, and 4L60-E. The first two are hydraulically controlled, and the third is electronic. All three will interchange mechanically (the 4L60 is simply a renamed THM700R4, given the new GM naming convention.)

 

[8Mud]

The noise you are hearing could be pump cavitation noises. Which can be caused by sheared (thin) fluid, cheap thin fluid, overheating (thin fluid) and sometimes a worn pump. Sometimes because of fluid starvation, low fluid, blocked filter. Or in the case of 700R4's on two seperate occasions on my truck, blocked cooler lines. Which is a really expensive lesson in the mundane.
Once the cooler line was almost completely blocked, the second time partially.
Compare the length of your dipstick, with another. My rebuilds were complete and sent with a new dipstick. One with the wrong dipstick.
My 700R4's seemed to be good at spitting metal when they were failing, anywhere from an ounce to a spoonful in the pan and filter.
I seem to remember flushing the cooler and cooler lines as being a warranty requirement. Not all that difficult and obviously some engineer thought it was important enough to include in the rebuild warranty.
Low pressures can be a killer in the 700R4, be careful shifting from reverse to forward and the other way around, wait for it to engage before you gas it.

 

[Mr_Random]

The noise you are hearing could be pump cavitation noises. Which can be caused by sheared (thin) fluid, cheap thin fluid, overheating (thin fluid) and sometimes a worn pump. Sometimes because of fluid starvation, low fluid, blocked filter. Or in the case of 700R4's on two seperate occasions on my truck, blocked cooler lines. Which is a really expensive lesson in the mundane.
Once the cooler line was almost completely blocked, the second time partially.
Compare the length of your dipstick, with another. My rebuilds were complete and sent with a new dipstick. One with the wrong dipstick.
My 700R4's seemed to be good at spitting metal when they were failing, anywhere from an ounce to a spoonful in the pan and filter.
I seem to remember flushing the cooler and cooler lines as being a warranty requirement. Not all that difficult and obviously some engineer thought it was important enough to include in the rebuild warranty.
Low pressures can be a killer in the 700R4, be careful shifting from reverse to forward and the other way around, wait for it to engage before you gas it.

No cooler on mine AFAIK. 88 1/2 ton 2wd suburban.

So you're suggesting dropping the pan for inspection, and if I don't find anything refilling the atf? What type of ATF? I'm thinking dexron III, but once again I don't know much about autos...

 

[8Mud]

There should be some sort of transmission oil cooler lines going to the radiator. While the tranny is empty, you may as well blow through the cooler and cooler lines to check for blockages.
A change of fluid may not help, but sure isn't going to hurt any. Pretty much the first step in any kind of serious troubleshooting. Save what comes out, in a clean container so you can inspect the Dexron.
You didn't mention whether the sound was worse cold or hot, louder during acceleration or whatever.
Have you adjust the TV cable lately?.

 

[four_shot]

dex III should be fine, it's what superceeded the Dex IIE that came in it. and there is a cooler built into the radiator, even if you dont have an external cooler. x2 on adjusting the TV (Throttle Valve) cable.

 

[blue95xj]

Another thing to remember is a rebuilt trans is only as good as the rebuilder.

 

[Mr_Random]

There should be some sort of transmission oil cooler lines going to the radiator. While the tranny is empty, you may as well blow through the cooler and cooler lines to check for blockages.
A change of fluid may not help, but sure isn't going to hurt any. Pretty much the first step in any kind of serious troubleshooting. Save what comes out, in a clean container so you can inspect the Dexron.
You didn't mention whether the sound was worse cold or hot, louder during acceleration or whatever.
Have you adjust the TV cable lately?.

Okay yeah, at least having lines to the radiator makes sense.

Um... it's usually noisier when cool and accelerating softly. Hard acceleration after warming up results in smooth, quiet shifts.

It's not like the thing shifts at the wrong spots or anything, it's just that when cold it whines until it makes a full shift. Sometimes the shifts are hard, but never clunky.

I have too much atf +4 sitting around, and it supercedes dexron/mercon III, can I use it?

 

[8Mud]

Okay yeah, at least having lines to the radiator makes sense.

Um... it's usually noisier when cool and accelerating softly. Hard acceleration after warming up results in smooth, quiet shifts.

It's not like the thing shifts at the wrong spots or anything, it's just that when cold it whines until it makes a full shift. Sometimes the shifts are hard, but never clunky.

I have too much atf +4 sitting around, and it supercedes dexron/mercon III, can I use it?

I've no experience with ATF-4, dealer changed two of my AW-4s to ATF-3 on two separate occasions and both had some slippage issues within weeks. Multiple refills with Dexron cured that.
If it isn't broken don't fix it, do you really want to take the chance with ATF-4. Dexron 3 may be a better solution and maybe cavitate less.
It gets cold here and the cold weather groan of the AW-4 is fairly common, until it heats up. Never seemed to hurt anything that I've never noticed. Tends to shift late and a little hard, until it heats up. I don't remember my 700R4 ever making pump noises, but it did tend to have a slight gear type whine when it was cold. I've trashed like 3 700R4's, I'm on my 4Th now, I'm not a big fan of that tranny. I really should have changed my 88 Chev. to the TH350, after the second 700R4 failure.
Pretty much the same thing with the power steering pump (cold weather groan), synthetic power steering fluid seems to help. I actually run a mix of regular power steering fluid and synthetic.
I've used Dexron, Dexron 2, Dexron 2a and Dexron 3, with no real differences that I've noticed, except the newer Dexrons seem to discolor quicker. They all seem to have about the same friction properties. I use Dexron/Mercon now, as it's readily available. And my two Chev.s ( 88 TH700R4 and TH 350), my 74 Dodge and two XJ's all use the same tranny fluid. My tow truck (71 Chev.) is still on the original TH350 (manual shift, auto) tranny, It's on it's second engine, the odometer has turned over so many times I've lost count.