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Discussion Starter · #1 ·
I have a 2004 Chevy Astro van 2WD 4.3L with a 4L60E automatic transmission and something is seriously wrong, but I have yet to figure it out. I definitely need some help. I usually do all my own repairs and I am very mechanically inclined, but this has me stumped. I even consulted a friend who knows a lot more than me and he was puzzled and asked that I share with him what was wrong once it has been diagnosed. I would probably be willing to drop the big wad of cash down for parts for a remanufactured transmission if needed, or for a remanufactured rear end and new axles.... BUT the van is not worth spending $1,500 (or more) times TWO. I need to definitively be able diagnose the problem so that I can decide how much I'm going to have to invest to get it going again. I bought it used from a municipal police department that used it as a crime scene investigation vehicle and it has no hitch on it, so to the best of my knowledge it has never done any towing. Here is what happened and what I have checked thus far....

I pulled out of the driveway at work and after I had cleared the 2 lanes of oncoming traffic and was in the crossover in the median I let off of the accelerator and heard a slap, pop, or bang. I instantly thought it might be trouble as it sounded like clapping/slaping two solid bricks together. I hoped it was just something I ran over. Then I pulled out and accelerated up to 55 mph. Then about a 1/2 mile down the road I heard what sounded like driving on a tire that was completely flat. I pulled off the road to check out my tires. I was surprised when they all looked fine. I realized something had to be wrong and I wanted to get my van to a better spot where I could investigate further. I put it in reverse to back up a few feet to better align me with the area I wanted to drive to, but the van would not move backwards. I wondered if something with my rear brakes had broken or locked up. I was able to move forward in D, but there was a good amount of resistance as the engine was struggling to move the van forward. There was a good clear spot nearby where I parked.

I thought somehow something had broken in the rear brakes and bound things up preventing the van from moving as normal. I jacked up the van and removed both of the rear wheels, removed the pads & rotors, then propped the calipers out of the way. I put the transmission in neutral. I replaced the rear wheels as it was easier to rotate the tires by hand than trying to rotate the lugs on the hubs by hand. The tires spun freely by hand, but after about 10 revolutions there was a clang noise and the tires stopped. I rotated the tire in the reverse direction and it no longer made the driveshaft move as it had been in the forward direction. Then the clang noise again and the tire stopped rotating in the reverse position. This made me think that it was possibly something going on in the rear end. I pulled the cover and I saw no obvious problems with the differential. I have the G80 rear end which I had never seen that type of rear end before. When I moved my tire foreward by hand slowly there was no movement in the rear end, but when I put my foot on the tire and give it a spin the tire moved a lot and the rear end moves a little. I didn't see anything that looked worn or damaged in the rear end. I cleaned up the parts, cover, and magnet and put the cover on with a new gasket and replaced the fluid. While both the rear wheels were still off the ground I cranked the van. It was still in neutral, but both rear wheels were slowly rotating forward. Then I shifted into Drive and, with the engine idling, the wheels would pulse several rotations forward, then slow to almost a stop and then repeat the pulse & near stop. I couldn't understand why the surge and slow was taking place. Then, I drove it the 1/2 back to work to leave it in their parking lot. The van made all sorts of popping, grinding, and clanging noises. When I stopped I put the transmission in neutral, but it would not roll backwards. I tried reverse and the nose of the van dived down and the rear bucked up, but the van never traveled any distance in reverse. I pulled it forward a few feet into the nearest parking space.

I thought that I might need to remove the driveshaft and see if the transmission would turn the output shaft while in reverse. Also, I could try to see if there were and weird noises, pulsing, or resistance to the output shaft turning when in Drive. But, I wouldn't necessarily know for sure the tranny was good if it only misbehaved while under a load.

I had ordered a set of shop manuals about a week before all this happened, and they have now arrived but I wanted to see if anyone had any ideas about how to diagnose my problem before I resorted to the shop manuals. I get bogged down in them because there is soooo much information in them.

How can I definitely determine if the problem is my tranny, my rear end,or both?
 

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Well one way to find out is to actually pin point where the noise is coming from, you can use an automotive stethoscope.

You could also remove the driveshaft but before you do that mark the drive shaft it is best to always reinstall it in the exact position it came out.

How does the transmission fluid look? pull the dipstick a few times look for any metal shavings, burnt smell or very dark/burnt fluid. Consider dropping the pan for further inspection, 4L60E transmissions hold about 5 quarts for pan drops so keep that in mind.

But this does sound more like a differential failure.
 

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If you lost reverse, but it still drives forward, then it may be the transmission. The bang you heard, could be the sun shell that broke inside of the transmission. The only way to know for sure besides the loss of gears, is to pull the transmission apart. I rebuilt my rear end in my 97 Silverado because it was making a lot of noise. Once I pulled it apart, I found a broken carrier bearing mount collar. So I rebuilt the rear end. New everything. Cost me $1100 in parts. A week and a half later, I broke the sun shell in the transmission. Took it the transmission shop, and had them do a performance rebuild, so there was another $2800. The owner of the trans shop, used to do a lot of business with our shop. He said that its very common to have the rear end and transmission go out like that at about the same time. Everything I did, and had done was high performance, so it did cost me more, but I dont plan on sailing my truck and its a show truck more or less although I do drive it every day. I didnt mind spending the money on my truck. I figure it like this, it would cost me a lot more to replace the truck, and over all, my truck is worth somewhere around $15000.
 
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If you lost reverse, but it still drives forward, then it may be the transmission. The bang you heard, could be the sun shell that broke inside of the transmission. The only way to know for sure besides the loss of gears, is to pull the transmission apart. I rebuilt my rear end in my 97 Silverado because it was making a lot of noise. Once I pulled it apart, I found a broken carrier bearing mount collar. So I rebuilt the rear end. New everything. Cost me $1100 in parts. A week and a half later, I broke the sun shell in the transmission. Took it the transmission shop, and had them do a performance rebuild, so there was another $2800. The owner of the trans shop, used to do a lot of business with our shop. He said that its very common to have the rear end and transmission go out like that at about the same time. Everything I did, and had done was high performance, so it did cost me more, but I dont plan on sailing my truck and its a show truck more or less although I do drive it every day. I didnt mind spending the money on my truck. I figure it like this, it would cost me a lot more to replace the truck, and over all, my truck is worth somewhere around $15000.
He would not have 2nd and 4th gear if the sunshell broke.
 

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He would not have 2nd and 4th gear if the sunshell broke.
I had 2ed, when mine broke, just no reverse, or 4th. Point is, untill you take things apart, you dont know what you have. If it was just the rear end, it would be making noise, and the issue would be there all of the time, not just in certain gears.
 
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I don't think he lost reverse... He wouldn't get the nose drop and rear end hike if he had lost reverse, right? Sounds like reverse is plenty strong, but not strong enough to overcome the binding. I'm wondering if it's not in the front. I don't recall seeing a "the noise is coming from here" mentioned above. On a whim, make sure your front wheels spin freely. I had my brake calipers flop over (lost a bolt b/c college me was dumb...) and bind inside my rims. This allowed me to move incrementally back and forth, but finally completely bound. I didn't know it until I was broke down at church one Sunday morning missing a bolt from both front calipers. 😕

Is it possible one of the C-clips came loose and is rolling around inside the G80 internals where it can't be seen? Or one of the clutch packs is dangling, so it looked alright when it was inspected, but has since fallen out of place? I find it hard to believe this is a transmission issue... I'm leaning something uncommon and dumb (dumb = extremely rare and specific) or we're examining the wrong area on the vehicle.
 

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Discussion Starter · #7 ·
None of the noises sound like they are coming from the front. Also, I failed to mention that both front wheels rotated freely by hand when I checked them, so my problems are not related to the front brakes.

I do have a video of the rear end when the cover was removed. I'll try to get it posted on here.
 

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Discussion Starter · #8 ·
I forgot to mention that The van did throw a MIL code on the way back to work, which was a P0756 (PCM sensed an irregularity in shift solenoid B).
 

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I had 2ed, when mine broke, just no reverse, or 4th. Point is, untill you take things apart, you dont know what you have. If it was just the rear end, it would be making noise, and the issue would be there all of the time, not just in certain gears.
I don't see how you had 2nd with a broken sunshell because if the sunshell breaks that is it no reverse, no 2nd and no 4th it's not going to grab for 2nd and not for 4th and reverse the splines literally shear off.

This video shows a good example of where these 4L60E sunshells fail.
 

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Discussion Starter · #10 ·
Here is a link to the video on YouTube where I have the rear end cover off and I am spinning the tire forward with my foot to evaluate the differential while moving:

 

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Discussion Starter · #11 ·
Here is a video link showing when the rear end cover and fluid were replaced and both rear wheels were off the ground in Neutral and in Drive with the van running:

 

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Did you see any metal debris inside the rear end when you drained the oil?
If no metals, rear end is good then.

Test transmission by manually selecting each gear position from 1, 2, 3 and R. Watch the rpms to see if it upshifts from 1 to 2 to 3.
 

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Here is a video link showing when the rear end cover and fluid were replaced and both rear wheels were off the ground in Neutral and in Drive with the van running:

That looks more like a rear end issue. You could try a junk yard swap. That would be the cheapest way out.
 

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I don't see how you had 2nd with a broken sunshell because if the sunshell breaks that is it no reverse, no 2nd and no 4th it's not going to grab for 2nd and not for 4th and reverse the splines literally shear off.

This video shows a good example of where these 4L60E sunshells fail.
I know what a broken sun shell looks like. Like I said, it just happened to me. I drove the truck to the transmission shop across town. When it broke, it sounded like a bomb went off. Im just saying what happened to me, believe what ever you want. I have about 750 miles on my trans rebuild, so this was very recent. I had about 250 miles on the rear end rebuild, when the trans blew.. The rear end I did my self. New gears, all new bearings and races, and an Eaton true trac.
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I may have not had 2ed, but like I said, no reverse and no 4th also.
 

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I know what a broken sun shell looks like. Like I said, it just happened to me. I drove the truck to the transmission shop across town. When it broke, it sounded like a bomb went off. Im just saying what happened to me, believe what ever you want. I have about 750 miles on my trans rebuild, so this was very recent. I had about 250 miles on the rear end rebuild, when the trans blew.. The rear end I did my self. New gears, all new bearings and races, and an Eaton true trac. View attachment 169100 View attachment 169101 View attachment 169102
Well good luck with it, I hope the transmission shop did the rebuild correctly but 750 miles can be too soon to tell. I currently have 123,000 miles on my S10 RWD which has a 4L60E and G80 Locker. Hoping to get 200,000 out of it, I bought it late summer last year only put 1,000 miles on it since I owned it, I baby it however it had one hell of a work out this past month moving a bunch of truck loads in town. I had a 94 Silverado 4.3 with a 4L60E make it to 250,000 miles it was still running and driving good when I sold it.

I think I will pay the $1400 for a ETE transmission from O'reilly if I ever run into needing a transmission which hopefully I don't. 3 year unlimited mile warranty and they gave me a list of the parts they use on their builds it is a really solid build honestly.

169105
 

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shops that build race car transmissions dont fail. I also have a stage 3 Heavy Duty 4L60E built by a mom n pop race shop that's been in the business for over 50 years and has seen the entire evolution of transmissions and know their ****. of course they rebuild all transmissions. now how did I find this gem? I actually went to a local GM dealer and asked them if they would do a rebuild on my truck, the head Master GM tech jumped straight to the point and gave me the business card for this shop. he said they do not rebuild transmissions, they only remove them and send them to this place for a rebuild and then they get it back in 2 days and reinstall it. the customer is none the wiser and pays double than what the tranny shop charges for the full R&R. he said most GM dealers in Southwestern Ontario send their trannys there too and he didn't want to touch my 21 year old truck. I said hey, I just replaced the transmission 20 000 kms ago! he burst out laughing.

A shop like this also stands behind their product even when out of warranty, if one of their trannys fails they actually want to know how and will probably still fix it for free. a shop like this also wants to know why the original tranny failed, they will do a fluid anylsis which they did and found coolant in the transmission fluid! so that's why the tranny i just installed failed as well as the original.

my 4L60E is rated for 600 HP and it sits behind the original untouched 350 with 333 337 miles! all stock! hahahaha

Al
 
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I dont see anything about upgrading the planetary gearset from the 4 to the 5, like what's in the 4L65E. I also have a brand new high performance Torque Converter. My truck was also dyno tuned as a part of the deal. they even tuned the car that dropped me off..... FOR FREE!
 

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shops that build race car transmissions dont fail. I also have a stage 3 Heavy Duty 4L60E built by a mom n pop race shop that's been in the business for over 50 years and has seen the entire evolution of transmissions and know their ****. of course they rebuild all transmissions. now how did I find this gem? I actually went to a local GM dealer and asked them if they would do a rebuild on my truck, the head Master GM tech jumped straight to the point and gave me the business card for this shop. he said they do not rebuild transmissions, they only remove them and send them to this place for a rebuild and then they get it back in 2 days and reinstall it. the customer is none the wiser and pays double than what the tranny shop charges for the full R&R. he said most GM dealers in Southwestern Ontario send their trannys there too and he didn't want to touch my 21 year old truck. I said hey, I just replaced the transmission 20 000 kms ago! he burst out laughing.

A shop like this also stands behind their product even when out of warranty, if one of their trannys fails they actually want to know how and will probably still fix it for free. a shop like this also wants to know why the original tranny failed, they will do a fluid anylsis which they did and found coolant in the transmission fluid! so that's why the tranny i just installed failed as well as the original.

my 4L60E is rated for 600 HP and it sits behind the original untouched 350 with 333 337 miles! all stock! hahahaha

Al
I don't agree with the whole "Shops that build race car transmissions don't fail" any shop can claim they build "Race car" transmissions or "Heavy duty" transmissions it doesn't mean they do it right or good.

I don't want to name any names but there is a big company out there and you probably seen or heard of it before if you type in google performance or heavy duty transmissions, but a lot of people are not happy with the products lately.

People in Texas should try to go to Precision Transmission in Amarillo they know what they are doing, check out their Youtube channel, hell they are so good people drive thousands of miles just to get it built there.

All I can say is always do research with whatever shop you choose. Seems like the one you went to is good so stick with them.

Nice mileage on that 350 they run forever if maintained.
 

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I dont see anything about upgrading the planetary gearset from the 4 to the 5, like what's in the 4L65E. I also have a brand new high performance Torque Converter. My truck was also dyno tuned as a part of the deal. they even tuned the car that dropped me off..... FOR FREE!
If you are referring to the ETE transmission, they don't sell their transmissions as performance transmissions, they sell them as replacement transmissions where they upgrade the weak common failure points, this is a transmission that you don't have to worry about for a long time for regular use. In many cases a 4 pinion is perfectly fine unless you are putting down some big numbers or doing heavy towing then you would want to upgrade to a 5 pinion.

For regular use applications what they do is more then enough.
 
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