Weird Transmission Problem

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JJ93

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Hi everyone

So few days ago I dropped the transmission pan and changed the fluid/filter (dexron vi, AC/Delco filter). The old fluid was not burnt, just a dark red. No shavings in the pan. Afterwards I drove it around to make sure everything was kosher. It drove great, no slips. Even under WOT it shifted perfectly. When I got home I noticed the fluid level was just a hair low, so I put in some more. I assumed I was good, so I left it alone after that and called it a day.

Today on my way in to town the transmission would not shift past second gear. It would just keep revving up in second gear, like it didn't even attempt to change into 3rd. It didn't slip or feel like neutral or anything like that. I pulled over and shut the truck off, restarted it, and continued to drive. It went into 3rd (and 4th) good (although a bit softer than normal), but when I got home I realized that the trans fluid was a bit too high so I drained out just a bit (1/2 quart?), the level is perfect now and it is shifting perfectly at all speeds and under all types of acceleration. No slips at all, even under WOT. I have had this happen before after a car wash (with the underbody wash), but after a minute or two it fixed itself. This makes me wonder if there is something electrical going on.

Is this something I need to worry about? Do I need to start saving for a trans? It is an '01 Suburban with 117k miles on it. The thing that concerns me is that the previous owner (my uncle, who bought it new in '01) used it to tow their camper and go on longer trips down south. I am hoping that the transmission isn't going to start giving me issues, I need this truck to be reliable enough to take it across the country if need be.

Any thoughts on this would be appreciated!
 

OR VietVet

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Quick question. When you checked and filled the trans fluid, either time, were you on level ground and did you check the fluid when it was hot and engine running? You also said the fluid was not burned but was dark red. That can be a sign of some overheated fluid or really old age. With 117k on the engine and I am assuming the trans, when was the last time the trans fluid was changed?

What is the size and weight of the towed trailer? How many towed miles are on the rig? Empty long trips to the south does not worry me as much as towed miles and the size of the towable.
 
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JJ93

JJ93

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Quick question. When you checked and filled the trans fluid, either time, were you on level ground and did you check the fluid when it was hot and engine running? You also said the fluid was not burned but was dark red. That can be a sign of some overheated fluid or really old age. With 117k on the engine and I am assuming the trans, when was the last time the trans fluid was changed?

What is the size and weight of the towed trailer? How many towed miles are on the rig? Empty long trips to the south does not worry me as much as towed miles and the size of the towable.

Both times were in my garage which is level, also with the engine running and after driving. After the first drive is when I saw that I needed to add fluid, so I did. After driving it today I checked the fluid level and it was a bit high, but I did drive it farther today than when I last checked it. I assume that the level might have been good before but I'm thinking I didn't get the trans warm enough to get an accurate level on the dipstick. After draining out the amount I overfilled it by, I drove it a half hour at highway speeds and stop and go, and the fluid level was perfect, right in the middle of the "hot" crosshatch. I didn't have one issue after getting the level back where it is supposed to be.

I do not think the transmission fluid has ever been changed on this truck. It wasn't too awful dark, but definitely not as light as new fluid. I changed that, both diffs, transfer case, and power steering fluid within the past week to catch up on maintenance, and except for the rear differential everything was full of original fluid from 2001.

I am not 100% sure on the size and weight of the trailer, if I had to guess it was a 28ft trailer. It was a late 90's Terry, probably 5,000 pounds give or take. Plus the gear, family, etc. He towed it around Michigan and down to Florida, as well as the Virginias. He said the rear differential was replaced because he had it blow out on him while towing, so I can only assume it was heavy lol. It does have 4.10 gears which helps. He said he never had issues getting up the mountains or anything though.

It seems to be driving as good as ever at the moment with plenty of get up and go, but just the randomness of the issue has me a bit concerned.
 

OR VietVet

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I hope it stays that way and no more problems but that is a lot of towing, especially if the fluid/filter has never been done before. It may be signs of things to come but keep driving it and report back. Make sure the front area of the P/s cooler, trans cooler and radiator are all clear and clean.
 
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JJ93

JJ93

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I hope it stays that way and no more problems but that is a lot of towing, especially if the fluid/filter has never been done before. It may be signs of things to come but keep driving it and report back. Make sure the front area of the P/s cooler, trans cooler and radiator are all clear and clean.

Will do. It seems to be driving perfect at the moment even on the interstate at 75 mph. I'll let everyone know if something else pops up but as of now I will just keep driving it. I hate intermittent problems lol, I am often in the Upper Peninsula and I would hate to have the trans go out in an area where there is no cell service lol.I already had that happen with my alternator back in October. That was fun, had to drive 35 miles on nothing but battery power to get to the closest NAPA.

I am debating on going back under the truck to see if any wires are rubbed through or something, since I have had the same issue after car washes as well. I haven't felt a slip or a false neutral any any point since I bought the truck back in July, so fingers crossed there is no actual internal issues starting to show their ugly faces
 

OR VietVet

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The other thing to remember is that the Sub is a 1/2 ton and towing that trailer all that time could also be ******* the drive train and suspension and steering. Make sure to check all of that and your brakes. I can only assume you got repair records and maintenance records with the rig from your uncle but if the trans service has never been done before, I am worried about those records and history as well.
 

rockola1971

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You had a valve in the valve body or a servo hang up. These transmission typically die around 125k depending on how much they are used to tow/plow and of course fluid changes. Even less than 125k if you tow in OD(4th). Just dont do it! You will burn the 2-4 band up.
 
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JJ93

JJ93

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The other thing to remember is that the Sub is a 1/2 ton and towing that trailer all that time could also be ******* the drive train and suspension and steering. Make sure to check all of that and your brakes. I can only assume you got repair records and maintenance records with the rig from your uncle but if the trans service has never been done before, I am worried about those records and history as well.

I know that he towed the trailer about 2-3 times per year, the rest of the miles are mainly just commuting/family outings. It sat a lot too, it was a backup car for the past few years. Before I got it he had all new brakes and brake lines professionally installed (front and rear), a new exhaust system, the rear end (brand new in 2018), and oil changes. Other than that, things were left alone (including the transmission). He is generally easy on his cars, so I would think he wasn't overloading the truck and then running 80mph down the fast lane lol. He has always been the guy who tows under the limit in the slow lane, overdrive off, tow/haul on, taking it easy up grades, etc.

When I got it I went crazy replacing things. Spark plugs/wires, wheel bearings, tie rods, ball joints, bushings, all fluids, filters, tires, alternator, everything that I thought was original got changed. It does have body rust which sucks, but I knew that going in. Frame is solid though.

I really want this truck to last me a while, it is a nice driving truck with only 117k miles. I would hope it has another 100k in it, at least with the engine. It doesn't even burn any oil between changes, which is something that surprised me.
 
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JJ93

JJ93

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You had a valve in the valve body or a servo hang up. These transmission typically die around 125k depending on how much they are used to tow/plow and of course fluid changes. Even less than 125k if you tow in OD(4th). Just don't do it! You will burn the 2-4 band up.

Interesting! I was wondering if something hung up like that, since it didn't slip or neutral out. It just didn't act like it wanted to shift into third. I could still accelerate just fine. I have had that happen once every couple hundred miles or so. Since then it has been shifting perfectly through every gear. I am starting to think that future issues are starting to peek around the corner.

I have some thinking to do about whether or not it is even worth it for me to save for a transmission in the near future, especially with the body rust on the back quarter panel and the rockers. That sucks, because it's such a good running/driving truck. I just don't know if I can depend on it like I want/need to.
 

OR VietVet

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Just how bad is all the rust? When something is paid off and you shared the list of all you have put in it. IMO, that doesn't mean it is time to throw in the towel on this rig. Look at all the way newer rigs on here that have problems worse than this.
 

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