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I have a problem with the Transmission in my 1990 GMC Suburban SLE V1500 4x4 5.7 350 V8.
It's a Turbo 400R4, and the problem is that it cam shift from 1-2 gear but not into 3rd. I bought the vehicle from the last owner and he told me about the problem.
He said that he was at a stop light and when the light turned green he went and the trans was not going into 3rd.
Long story short, my buddie who owns aa paint and body shop and I looked at the trans fluid dipstick and it was nearly no fluid on it.
We put in a new fluid filter, gasket amd right amount a fluid and he drove Suburban around the block and said the trans was slipping. Even though it shifted from 1st to 2nd amd goes in reverse with no problems.
He say's it needs a rebuild, but I'm thinking that the trans needa a new silinoid or gear adjustment.
Plus, when the truck is put in park, you can still move it unless the E Brake is on.
It could just be a sticky shift solenoid. Before you go for a rebuild you might want to try a drain and refill with the addition of some Lucas Transfix. A lot of guys on the Caddy boards swear by it. It's worth a shot and a whole lot cheaper than a rebuild.
FWIW
YMMV
It could just be a sticky shift solenoid. Before you go for a rebuild you might want to try a drain and refill with the addition of some Lucas Transfix. A lot of guys on the Caddy boards swear by it. It's worth a shot and a whole lot cheaper than a rebuild.
FWIW
YMMV
I have a problem with the Transmission in my 1990 GMC Suburban SLE V1500 4x4 5.7 350 V8.
It's a Turbo 400R4, and the problem is that it cam shift from 1-2 gear but not into 3rd. I bought the vehicle from the last owner and he told me about the problem.
He said that he was at a stop light and when the light turned green he went and the trans was not going into 3rd.
Long story short, my buddie who owns aa paint and body shop and I looked at the trans fluid dipstick and it was nearly no fluid on it.
We put in a new fluid filter, gasket amd right amount a fluid and he drove Suburban around the block and said the trans was slipping. Even though it shifted from 1st to 2nd amd goes in reverse with no problems.
He say's it needs a rebuild, but I'm thinking that the trans needa a new silinoid or gear adjustment.
Plus, when the truck is put in park, you can still move it unless the E Brake is on.
You need a rebuild plain and simple.
There is no such thing as a TH400 with over drive. If it's a TH400 it's a 3 speed. If it has over drive it's either 700R4 or a 4L60E or 80E but I don't think those came along until much later. Most likely it's a 700R4 4 speed auto with over drive.
This vehicle can have either the THM400 or the 700R4 tranny.
Frankly, without a little more hands-on diagnosis, it's tough to say what's wrong with it. If you ran it dry - or nearly dry - you're probably looking at a rebuild. On the other hand, it's possible that you've got a stuck valve or solenoid.
If you want to try the cheapest thing first, pour some TransTune or TransX into it, and run it. See what happens. You might get lucky. Or pour some straight Seaform into it, run it 50 miles, flush it & change the filter & fluid again. Don't run it very long with Seafoam in it before draining it. Either of these "long shots" might dislodge some crud, and loosen a check-valve or shift solenoid.
You could also add some Lucas Transmission Stop-Slip. That product is about as good as there is for helping slight slippage. But it's a long-shot.
You don't have much to lose by trying these easy fixes, but they're not apt to fix the real problem. Good luck!
Sorry, I meant th400 but it does have an overdrive whih say's it on the gear meter.
No 400 has overdrive. You either have a 200r4 but mist likely due to the year of vehicle its a 700r4. Hit up a junkyard. Those are plentiful. Find one behind a 350 camaro or full size truck. They are also relatively cheap to buy already rebuilt online the 4l60/80e didn't come to be until 94 or so
No 400 has overdrive. You either have a 200r4 but mist likely due to the year of vehicle its a 700r4. Hit up a junkyard. Those are plentiful. Find one behind a 350 camaro or full size truck. They are also relatively cheap to buy already rebuilt online the 4l60/80e didn't come to be until 94 or so
So it might be a 700r4, but my buddie said their is none fora 4x4 Suburban
So it might be a 700r4, but my buddie said their is none fora 4x4 Suburban
What do you mean? The 700r4 was used in suburbans. If it has PRND21 its a 400 three speed. If its a PRNDD21 (the first D has a O around it ) its a 700r4. 1990 was a change over year because they had the redesigned C/K pick ups and a lot if TBI motors and drive trains were being put in the old square body which only lasted till 1991 only on suburbans and I think K5 blazers then they all switched to the CK front ends.
I believe the only suburban that still may of had the oddball 400 was one with a 454 CID big block.
Crawl under there look at the pan. If it's all squared off on all four sides its a 700 if it looks a bit like the state of Texas its a 400. I think by then the speedo gear may of been electronic so on the tail shaft you'll either have a plug in or a round knob with a cable coming out if it. That's. Where the odometer hooks up to read mileage
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