JavaMan
OBS Enthusiast
I bought a 1996 Suburban 2500 4x4, with the 454 and 4l80e about a year ago with 113k miles on it. It was priced at $5000, but when I went in to look at it, they said it needed fuel lines replaced which was to expensive for them to do, so they offered to sell it to me as-is for $4k. They gave me $2500 for my 99 Sierra 1500 4x4, which they claimed they input the miles as 17k rather than 173k, but they honored their original offer of $2500 anyway. So my out of pocket was only $2100 after everything at the dealership, plus $280 in parts to replace the fuel lines and pump. Not bad for getting extra room for the family, dual AC, and 3/4 ton.
First month I replaced the fuel lines and pump, changed the oil, changed the trans filter and drained and filled 8 qts ATF (used Valvoline MaxLife, full synthetic Dex3 and Dex6 compatible), changed the rear diff oil, cleaned the AC coils as best I could through where the blower mounts. It drove great.
Then the problems, sorry it gets long here.
By February, I was noticing that going up hills sometimes it would jump to rev limiter, I'd back off the throttle and it would grab again. I found if I just stay easy on the throttle it would be fine, or I could speed up before the hill and let it easy slower getting to the top, and I could prevent the slip.
Well, I thought I'd try a B&M Electronic shift improver, supposed to boost the trans fluid pressure to make firmer shifts. It was great firm shifts 1-2, and 2-3...then neutral. 4th gear felt like nothing was there, it would shift from third and feel like neutral, slows down a bit, then shifts into third again and speeds up. I turned the B&M to stock position, and 4th would kick in and drive like normal. I thought that was weird, and didn't want to break anything, so I removed the B&M.
We took it on a trip to California beginning of June. It was hot going across the California desert, 115-118. Engine was running hot, approx 240. Driving along at 75 on flat road, the RPM goes up, start slowing down so I give a bit more throttle and the RPM jumps like it's in neutral. I manually shift to third, it kicks in and we keep going. Shifting to third helped cool the engine some too, down to 215. We get into Palm Springs, I bought some Water Wetter, and added it in. (Hindsight thought, no pressure was released when I opened the radiator cap). We get out of the desert, still driving in third. That week in San Diego area temps in the 80s, 4th gear would work fine for the first 5-15 miles, then would start slipping in 4th, so I'd shift to 3rd and continue on. On the way home, it was trying to overheat in the desert. About 20 miles from home, going up the hill (climbing from 3000 feet to 7000 feet), it was approx 240 for a way. Then it rapidly went up to 260, and I pulled over and turned it off. We started adding water, then noticed it going all over the ground. One of the nylon splitters for the heater hoses had let go. Got towed into town, it was Saturday so no one at the shop, I went to parts store got the nylon connector and replaced it myself. Filled it up with coolant, put a new radiator cap on it, because I figured out it wasn't holding pressure. Overheat problems solved, even when we towed a 6k pound trailer to Phoenix, with several up and over mountains from Flagstaff. Pulled in third of course.
Now that the temperature is going down, when it's in the 60s, 4th gear works fine. Even after 40 miles and going over hills, 4th does not slip when the outside temps are in the 60s.
I've tried searching the internet, and can't find what causes 4th to slip when the ambient temps are warmer than 70, but not slip when it's colder. Repair shops are money hungry, all three of them heard "slip" and without even looking at it told me rebuild the trans, $3k to $4k. That's just the internals, they don't think I need any work on the valve body, cause that part doesn't really wear out till around 200k miles, and I'm only at 118k.
Any ideas before I have somebody rebuild it? Should I drive it down to Phoenix where there's some better shops and build it as a 4l85e? We do tow 4k to 6k trailers a few times per year.
First month I replaced the fuel lines and pump, changed the oil, changed the trans filter and drained and filled 8 qts ATF (used Valvoline MaxLife, full synthetic Dex3 and Dex6 compatible), changed the rear diff oil, cleaned the AC coils as best I could through where the blower mounts. It drove great.
Then the problems, sorry it gets long here.
By February, I was noticing that going up hills sometimes it would jump to rev limiter, I'd back off the throttle and it would grab again. I found if I just stay easy on the throttle it would be fine, or I could speed up before the hill and let it easy slower getting to the top, and I could prevent the slip.
Well, I thought I'd try a B&M Electronic shift improver, supposed to boost the trans fluid pressure to make firmer shifts. It was great firm shifts 1-2, and 2-3...then neutral. 4th gear felt like nothing was there, it would shift from third and feel like neutral, slows down a bit, then shifts into third again and speeds up. I turned the B&M to stock position, and 4th would kick in and drive like normal. I thought that was weird, and didn't want to break anything, so I removed the B&M.
We took it on a trip to California beginning of June. It was hot going across the California desert, 115-118. Engine was running hot, approx 240. Driving along at 75 on flat road, the RPM goes up, start slowing down so I give a bit more throttle and the RPM jumps like it's in neutral. I manually shift to third, it kicks in and we keep going. Shifting to third helped cool the engine some too, down to 215. We get into Palm Springs, I bought some Water Wetter, and added it in. (Hindsight thought, no pressure was released when I opened the radiator cap). We get out of the desert, still driving in third. That week in San Diego area temps in the 80s, 4th gear would work fine for the first 5-15 miles, then would start slipping in 4th, so I'd shift to 3rd and continue on. On the way home, it was trying to overheat in the desert. About 20 miles from home, going up the hill (climbing from 3000 feet to 7000 feet), it was approx 240 for a way. Then it rapidly went up to 260, and I pulled over and turned it off. We started adding water, then noticed it going all over the ground. One of the nylon splitters for the heater hoses had let go. Got towed into town, it was Saturday so no one at the shop, I went to parts store got the nylon connector and replaced it myself. Filled it up with coolant, put a new radiator cap on it, because I figured out it wasn't holding pressure. Overheat problems solved, even when we towed a 6k pound trailer to Phoenix, with several up and over mountains from Flagstaff. Pulled in third of course.
Now that the temperature is going down, when it's in the 60s, 4th gear works fine. Even after 40 miles and going over hills, 4th does not slip when the outside temps are in the 60s.
I've tried searching the internet, and can't find what causes 4th to slip when the ambient temps are warmer than 70, but not slip when it's colder. Repair shops are money hungry, all three of them heard "slip" and without even looking at it told me rebuild the trans, $3k to $4k. That's just the internals, they don't think I need any work on the valve body, cause that part doesn't really wear out till around 200k miles, and I'm only at 118k.
Any ideas before I have somebody rebuild it? Should I drive it down to Phoenix where there's some better shops and build it as a 4l85e? We do tow 4k to 6k trailers a few times per year.