10L1000 anyone with High Mileage ? I hate Damocles....

[Chuck FB]

20 minutes ago, XY74 said:

I had 72K on my 2020 truck when I traded it right at 1 year ago.  (found out about recall when they ran a vin check)  The transmission worked perfectly.  (so did the rest of the truck)  I dropped the pan and changed the filter at 45K, it all looked fine.  I have 17K on the new truck, it's been perfect.  (knock knock)  Both are diesels FWIW.  75% of the time has a trailer of some sort attached. 

 

No doubt it's a real issue, but sure doesn't seem to be that widespread. 

From what was said and I don't know if there was truth to that or not, that the early or first model valve body that would have come on some or all of the 2020 models was possibly less prone to issues over a reworked design that came after that. I have no idea if there is any truth to that or not but early this year when I had a little chat with the service manager at the dealership at the time of purchasing my gas HD, he did say that they were having some HD trucks ( also the half tons with their 10 speed version ) sitting for months on their lot waiting for valve bodies because they were in very short supply. 

 

This summer and to be clear it was on a half ton truck of my friends, a 2023 with the 6.2 ( which by the way it recently passed its pico health test at the dealer so now officially runs 0W-40 ), had his transmission fail to shift or find reverse or forward properly all in a matter of a few miles going to work one day out of the blue and it got towed to the dealer. They diagnosed and said its the valve body and then it was sitting there waiting on a valve body and from what I can gather at least, they installed that valve body and so far its shifting fine again. He would have had around or just over 20000 miles on the truck at the time and he has towed a smaller aprox 5000 lb holiday trailer some before the trans issue, the truck has the 3.42 axle as it has the towing package. He likes his truck, how it performs and so on but that trans issue certainly was a nasty set back but they were able to give him a pickup for the month that his was tied up which was a huge deal. 

[20L8TSierra24]

42k on my 24.

 

-Valve body @ 12k

-Pump, stator, and some support at right around 18. 

 

Now, it's starting to whine like a 20 yr old air conditioners capacitor when coasting to a stop. 

[Chuck FB]

7 minutes ago, 20L8TSierra24 said:

42k on my 24.

 

-Valve body @ 12k

-Pump, stator, and some support at right around 18. 

 

Now, it's starting to whine like a 20 yr old air conditioners capacitor when coasting to a stop. 

 

Have you talked to the dealer or had them listen to it yet or would they prefer it comes in on a tow truck after it grenades. My guess is that may be preferable or unless they would say now, will install a new transmission. 

 

You've certainly had the trans oil changed, one has to wonder if its the fault of the tech or its just crappy parts, or when the other parts were failing it damaged other internals of the transmission. 

 

Years ago when I bought a new chev half ton, 6000 miles into ownership the trans was slipping its 2/4 band and it also slipped the 3/4 clutch pack and what they found was a cut oring from the factory assembly on the 2/4 piston servo that applies the band. They went through the trans and replaced what needed it beyond a trans clutch kit and it actually did last for quite a while, I've lost count with how many transmissions have gone into that thing as the 4L60E had a horrible track record and I rarely towed anything. The price of a reman trans was NOTHING compared to what these transmissions cost now. 

[OS RR]

I feel like something that needs distinguished everytime someone has a valvebody (or what have you) go bad. 

 

What engine and what kind of life has the truck lived so far.

[lineman1234]

Getting close to 50,000 miles, no transmission problems, just the sound it has made from new that seems to be the way it is. 

 

About 6,000 miles towing a 10,000lba 5ver and now about 3,000  miles with a truck camper traveling. About 500lbs under my max payload ratting. 

 

Ill do the transmission service myself this summer.

[Chuck FB]

6 hours ago, lineman1234 said:

Getting close to 50,000 miles, no transmission problems, just the sound it has made from new that seems to be the way it is. 

 

About 6,000 miles towing a 10,000lba 5ver and now about 3,000  miles with a truck camper traveling. About 500lbs under my max payload ratting. 

 

Ill do the transmission service myself this summer.

 

When you do the trans service and I assume you will change the filter at that time, it will be interesting to see what work around method you might come up with to get that pan out of there because of the exhaust cross over. Also what method you will use to refill the trans and perhaps a more definitive volume of what the trans actually took which one only knows after warming it up and draining out the excess. 

[lineman1234]

1 hour ago, Chuck FB said:

 

When you do the trans service and I assume you will change the filter at that time, it will be interesting to see what work around method you might come up with to get that pan out of there because of the exhaust cross over. Also what method you will use to refill the trans and perhaps a more definitive volume of what the trans actually took which one only knows after warming it up and draining out the excess. 

Being a regular cab/2 door, it will be interesting if the crossover tube is the same as on the 4 doors or different. 

   By looking at mine, it looks snug but i cant see any reason why the pan wont sneak out of there. 

 

Could always be worse. Could be a diesel and need the cab taken off to work on certain things. 

 

 

[Chuck FB]

7 minutes ago, lineman1234 said:

Being a regular cab/2 door, it will be interesting if the crossover tube is the same as on the 4 doors or different. 

   By looking at mine, it looks snug but i cant see any reason why the pan wont sneak out of there. 

 

Could always be worse. Could be a diesel and need the cab taken off to work on certain things. 

 

 

 

Good question if they routed it differently or not as I have not looked under a regular cab to see, however the engine to trans relationship itself and being a 4x4 would all be the same so only speculating that more than likely its going to be very similar. I know some have mentioned a youtube video which I have seen as well which where he undid a hanger bracket that is attached to the side of the transmission and then popped the rubber off the hanger further back and then used a ratchet strap in the area of where the Y pipe connects to a two bolt flange and pulled down hard on the pipe. What he had not done was loosen off those two bolts on the flange for concern of creating an exhaust leak but it put a ton of stress on that flange area. With his method he was just able to slip the pan out but there was no way on his truck that it was coming out without gaining that bit of Y pipe clearance and I would have to look at some photos and videos again but I believe its the valve body and certainly the filter that hangs below the transmission to pan bolt line. The tolerance was tight enough that he found he could not put the gasket on the pan and slip it into place, he had to put the pan into the area so to speak first, then slip the gasket on top of the pan. What I have never determined yet is if its physically possible to remove the filter with the pan still wedged up there dangling and not have to remove the pan at all, pain in the rear but clean it out/clean magnets as it sits there, I am sure that is possible but I do not know if the filter can come out with the pan hung in the way. The 2024+ trucks just haven't been out long enough for enough do it yourselfers who are in turn youtubers or on this site for example explaining what they did. You probably have seen the GM manual pages posted on here as they say to remove the whole Y pipe and the risk of bolts twisting off at the exhaust manifolds as well as having to remove the fender liners or so I think just to gain access to some of those bolts. That was the one bonus of the Duramax, the exhaust is routed differently so is not in the way of the pan ( but lots of other negatives as you point out that come with the diesel platform when things go sideways which is why I decided to go gas ). 

[garagerog]

On 11/25/2025 at 8:29 PM, Chuck FB said:

Just curious if your p/u with the 4L60 had a factory towing package that included the additional factory trans cooler mounted in front of the a/c condenser. With Dexron III being the standard up until 2006, it's my understanding that those 4l60's didn't tolerate getting too hot.

 

Years ago when I bought a new chev half ton, 6000 miles into ownership the trans was slipping its 2/4 band and it also slipped the 3/4 clutch pack and what they found was a cut oring from the factory assembly on the 2/4 piston servo that applies the band. They went through the trans and replaced what needed it beyond a trans clutch kit and it actually did last for quite a while, I've lost count with how many transmissions have gone into that thing as the 4L60E had a horrible track record and I rarely towed anything. The price of a reman trans was NOTHING compared to what these transmissions cost now. 

 

[lineman1234]

I could be wrong, but dont the 2025's have the filter on the outside for the transmission, so its only the gasser in 2024 when it got the 10 speed having the filter on the inside. 

 

I will if needed probably try the float the exhaust and pull it down some to get room. 

      I wont be running my 3500 into the ground, so ill probably only be doing 1 transmission service for my usage. 

[Chuck FB]

27 minutes ago, garagerog said:

 

 

Yes my truck had all the coolers they put on the half ton extended cab 4x4 at the time, the internal rad cooler and the external cooler in front of the condenser such as it is. Also that truck rarely towed anything and when when it did it was a quad on a small trailer and was never in the habit of driving the truck hard and a majority of its life it would go to town 50 miles away from the farm and a few stops in town and back home, also some long distance drive vacations but not pulling anything and just what I had packed under its low rider cover. So the first trans after its 6000 mile warranty issue went another 115000 miles before slipping and I had a reman installed, and through the ownership of the original trans I changed the oil a few times fully by the trans itself pushing out the old oil out of the converter etc. I would have to look in my maintenance book to see if its three transmissions or more that went into it, I fault some of that from crappy remans as one did something crazy inside and of course always after the reman warranty was past. This last reman I have had in there for some time now, I had the mechanic who swapped in the trans put GM Dex VI in it and that seems to be working fine and I haven't bothered to change the oil in it. I never had oil that looked very bad at all all through the years in any of the transmissions and certainly never a bad smell, changing the oil was not giving me the life it should have. I could see if I was cooking the oil, then that spells disaster. This Dex VI oil has stayed bright red like the day it was put in as an interesting note. By the way this truck has the 3.73 optional gearing with the more desirable semi float 14 bolt rear end as I believe there was a faster ratio choice and that would not have been any good at all for the trans. Also years ago now I had installed a rad that is meant to go into the 3/4 and 1 ton trucks that is thicker with another row of cores and that helps keep the engine temps in check along with a modification I did to the bimetal spring on the thermostatic fan for it to kick in at a lower temperature. Definitely the factory setup left a LOT to be desired if one would have actually used it for towing. The 3/4 using much the same engine at the time had the thicker rad but they also had a stronger fan drive and used a deeper blade fan which moves quite a bit more air. I would have had a better truck platform had I bought a 3/4 ton at the time as it would have come with the 4L80, their issue was their first gear was so fast. 

 

By the way about the quote method of replying, once you choose the quote option and it opens up the new box for you, scroll down if needed to type below the box as that way one can tell who typed what and also as you will notice in the quote I used from your comment, there is nothing in it as no words were typed below the box for it to show up. Hopefully that makes sense in how I attempted to explain that !. I don't know how to do much on sites like this but did figure out the quote deal, after some trial and error. 

[Chuck FB]

1 hour ago, lineman1234 said:

I could be wrong, but dont the 2025's have the filter on the outside for the transmission, so its only the gasser in 2024 when it got the 10 speed having the filter on the inside. 

 

I will if needed probably try the float the exhaust and pull it down some to get room. 

      I wont be running my 3500 into the ground, so ill probably only be doing 1 transmission service for my usage. 

 

Unfortunately when they went away from what was considered the real Allison ( which I believe was still being built by GM but Newdude would know more about that ) in 2019, they had an external spin on filter as well as a filter in the trans but it was claimed that normally the internal filter was not required to be changed unless work was being done on the transmission. When the 10L1000 came out in 2020, the only filter I have been aware of is the very same filter that fits the gas trans model although there is some internal trans differences that I still have not heard what they are, but they are not identical transmissions as the Duramax has a higher torque input rating then the gas version. However the Duramax with the way the up pipes are used to route exhaust to the turbo and then a single down pipe, that gets rid of the V8 idea of having two exhaust pipes coming rearward and frees up that pan area where the gas needs that cross over pipe since its not a true dual exhaust. 

 

I wasn't sure what your plans were with your truck, if you were going to run it until the wheels fell off of it or send it down the road at some point and choose whatever else that made sense at that point and sounds like the latter is in the cards. 

[garagerog]

Chuck, sorry I fubared the quote, some sites will let you copy and paste the relevant parts you want to respond to, guess I forgot this is one of 4 forums I follow that you can't do that. Anyhow the reason I asked about your experience with the 4L60 is that's what's in the '05 K1500 that I inherited from my Dad, it's an extended cab so it has the L33, 3.42 G80, and the towing package. Dad only used it to tow a snowmobile trailer with a couple of sleds a few times, so light load and very cool ambient temps. While he had it, it had one spill and fill with a filter change at a dealer, confirmed with the service tech that it had the round magnet, the old rectangular fiber magnetic infused "magnets" were vastly inferior. Anyhow after Dad passed and this has been some 9 yrs. ago I drove this p/u cross-country from ea. wash. state to SC. As of now it only has a little over 51K miles on it, and as I'm old and arthritic this will be my last p/u. Wanting to get all of the old Dex III out as it only had about 6 quarts of VI in it I had the local Chev dealer do a trans fluid exchange as well as a much needed Dexcool exchange. On the way home from the dealer I couldn't feel 4th gear TC lockup so I checked the trans fluid level and sure enough it was overfilled by 2 quarts. After I got the extra 2 quarts pumped out thru the dipstick tube, it operated as expected. About the same time I decided to replace the instrument cluster due to a bad stepper motor on the voltmeter and the odometer started resetting itself with each ignition cycle. I opted to get the optional transmission temperature gauge in the rebuilt cluster. Takes from 5-7 miles of moderate city driving for the needle to start to move off of the full cold peg, normal operating temp seems to be in the 150 range after prolonged driving. This last summer I did see it get up to 180 once in heavy city stop and go driving, but I think the second electric radiator fan must have kicked in as quickly dropped back to 150. I guess one thing that can be said for the 4L60 is that they're not tempermental in needing a little heat in them for the TC to lockup. Oh, one other thing, I found out by accident when re-installing the instrument cluster that Dad's p/u has power folding mirrors, I don't think he ever knew that, surprised me as it only has the LS trim.

[Chuck FB]

10 hours ago, garagerog said:

Chuck, sorry I fubared the quote, some sites will let you copy and paste the relevant parts you want to respond to, guess I forgot this is one of 4 forums I follow that you can't do that. Anyhow the reason I asked about your experience with the 4L60 is that's what's in the '05 K1500 that I inherited from my Dad, it's an extended cab so it has the L33, 3.42 G80, and the towing package. Dad only used it to tow a snowmobile trailer with a couple of sleds a few times, so light load and very cool ambient temps. While he had it, it had one spill and fill with a filter change at a dealer, confirmed with the service tech that it had the round magnet, the old rectangular fiber magnetic infused "magnets" were vastly inferior. Anyhow after Dad passed and this has been some 9 yrs. ago I drove this p/u cross-country from ea. wash. state to SC. As of now it only has a little over 51K miles on it, and as I'm old and arthritic this will be my last p/u. Wanting to get all of the old Dex III out as it only had about 6 quarts of VI in it I had the local Chev dealer do a trans fluid exchange as well as a much needed Dexcool exchange. On the way home from the dealer I couldn't feel 4th gear TC lockup so I checked the trans fluid level and sure enough it was overfilled by 2 quarts. After I got the extra 2 quarts pumped out thru the dipstick tube, it operated as expected. About the same time I decided to replace the instrument cluster due to a bad stepper motor on the voltmeter and the odometer started resetting itself with each ignition cycle. I opted to get the optional transmission temperature gauge in the rebuilt cluster. Takes from 5-7 miles of moderate city driving for the needle to start to move off of the full cold peg, normal operating temp seems to be in the 150 range after prolonged driving. This last summer I did see it get up to 180 once in heavy city stop and go driving, but I think the second electric radiator fan must have kicked in as quickly dropped back to 150. I guess one thing that can be said for the 4L60 is that they're not tempermental in needing a little heat in them for the TC to lockup. Oh, one other thing, I found out by accident when re-installing the instrument cluster that Dad's p/u has power folding mirrors, I don't think he ever knew that, surprised me as it only has the LS trim.

 

No problem at all, I just wanted to give you that heads up as it would confuse someone else that may happen to read through a thread. I don't know the tricks to doing a lot of the manipulating of someone elses comment, highlighting, underlining ect, and I don't really worry about it either as I am not a techy person and it is what it is !. So about your 4L60, I wonder what changes they have made to them in that 10 year span as I believe the shop if they order a reman goes off of the vin or year of the truck as I've never had that conversation with a trans rebuild shop to know what if any differences there are mechanically or electronically. Your engine although a bit smaller than a 350 puts out far more horsepower and why I wonder if changes had been made to the trans. I have to wonder if that over fill situation caused foaming or what went on that it would not work properly but goes to show goofy things can happen if its over full and not very professional of a dealer at that to leave it that over full as it certainly should have shown up to the person working on it. Back in 1995 they never had such a gauge as a trans temp gauge and not sure if there is an idiot light on the dash for trans over temp as manufactures didn't include all the stuff they do these days and the trans would have to have a sensor in it or in a line to sense the temps. Also as you point out they went to electric fans and unless I was getting idiot AI answers it looks like 2005 was the first year for the electric fan on the half tons. That was always the struggle with my truck, mechanical fan and if in hotter weather and using the air conditioning it was not capable of controlling the coolant temp to my liking,  not even a question when sitting still because of the low fan speed and even if the clutch would have locked up the fan speed would still have been too slow and why electric fans have their good points and yes add to fuel economy when not needing to run. With the temps your seeing on your trans, sounds like its all functioning as I imagine the engine temp runs in that 190 range assuming its not weak and opening sooner or that a cooler thermostat had been installed. I never had issues even in stupid cold weather and with the original Dex 3 fluid for the torque converter not locking up, sure when it was really cold the trans would react differently and not shift up the same as its warming up to a point where it will fully function but I am talking really cold temps. Not that its exactly comparable but with my 2025 truck with the gas and 10 speed, during the summer time with a 70 degree day lets say and driving along at 60 it would take at least 35 miles before the temp will top out where it stabilizes at around 145f and that is where it hangs in at although I imagine it would probably creep up a bit from there if driving fast in the same ambient temps. I had forgotten to look at it the other day when I went to town with colder weather around 0f as to if it reached that temp or not but assume what I observed in the summer is a temp regulator controlling the flow to the rad/cooler, where as its been said the 1/2 ton with the 3 litre duramax is set up to jack the temps up to near 200f because of how high the trans thermostat is set to but the gas 1/2 tons are set lower for trans temp, make sense of that one !. 

 

Probably the biggest issue these days with rads as in the air con and engine/trans rads is external with bugs and crap plugging up the fins or certainly the air con rad having smashed fins from bugs and road debris hitting it and killing the air flow able to pass through, that certainly won't help the engine or trans cool like it could when the rads were not damaged or unobstructed. 

[lineman1234]

12 hours ago, Chuck FB said:

 

Unfortunately when they went away from what was considered the real Allison ( which I believe was still being built by GM but Newdude would know more about that ) in 2019, they had an external spin on filter as well as a filter in the trans but it was claimed that normally the internal filter was not required to be changed unless work was being done on the transmission. When the 10L1000 came out in 2020, the only filter I have been aware of is the very same filter that fits the gas trans model although there is some internal trans differences that I still have not heard what they are, but they are not identical transmissions as the Duramax has a higher torque input rating then the gas version. However the Duramax with the way the up pipes are used to route exhaust to the turbo and then a single down pipe, that gets rid of the V8 idea of having two exhaust pipes coming rearward and frees up that pan area where the gas needs that cross over pipe since its not a true dual exhaust. 

 

I wasn't sure what your plans were with your truck, if you were going to run it until the wheels fell off of it or send it down the road at some point and choose whatever else that made sense at that point and sounds like the latter is in the cards. 

There always seems to be doom and gloom with almost any vehicle. 

 

   I did a bunch of research on the 2024 cheby 6.6 gasser and 10 speed transmission. Out of the big 3 3500 choices and not wanting another diesel, as i dont and really never needed one, i chose a 3500 chevy 6.6 gasser.. 

 

As long as i have the camping/wandering need, the currant pig will more than fit my needs. 

If i loose the camping bug,  ill get a fun vehicle travel and rent as needed. 

 

Being this is a transmission thread....   

   It never crossed my mind to go to the dealer or comment on the personality of the transmission. 

   It will make a noise at times with temp, speed, gear, that seems to me, to be normal, and i can live with that. 

   Under load, like going up a hill, towing, loaded with my truck camper, never do i hear the transmission sound/s.