When in D or O-D car won't accelerate beyond 25mph

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Vehicle specs in signature. Recently when driving in Drive or Over-Drive my car won't accelerate beyond ~25mph. It drives fine until 25, and then if I try to accelerate more the engine runs and spins as if in neutral but the speed of the vehicle remains the same. If I switch to what I think is 2nd(I'll explain the 'think' in a moment) I can get up to around 35-40. I've been able to hit 45 but that didn't feel safe. Also when I was at 45 and coasting downhill I was actually losing speed. The 'think' of 2nd Gear: My gear selector has P, N, R, O-D, D, 2, and 1 listed. I can switch from P through D normally but when I get to 2 I can't switch any further even though the selector shows I should be able to. I know P through R are correct, but I don't fully know if O-D through 1 are. I usually drove it in O-D but on my last trip I drove it in 2 so I could go 35 instead of 25. We've had this car for 10-15 years, don't remember exactly. I know we had some rear end work done on it around 10 years ago. I thought we had some transmission work done as well, but I can't remember exactly. I'd like to hear y'alls thoughts and opinions. I fear I am in need of some major transmission work. frown I have one specific question first though: If needed, can I drive it in 2 over short distance without further damaging anything? I have a weekly obligation about 5 miles away, town is 10 miles, and the mechanic is about 5 miles away. Thanks in advance.
 
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The good news is this is about the cheapest tranny to redo in the history of motoring. I believe you lost the "sun shell" in your 700R4, which means you need a "hard parts" rebuild, which will still be cheap.
 
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Originally Posted By: eljefino
The good news is this is about the cheapest tranny to redo in the history of motoring. I believe you lost the "sun shell" in your 700R4, which means you need a "hard parts" rebuild, which will still be cheap.
just did this to my boss's blazer including labor. cheapest place was $1300.thats not cheap to me lol
 

JasonTL

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Originally Posted By: eljefino
The good news is this is about the cheapest tranny to redo in the history of motoring. I believe you lost the "sun shell" in your 700R4, which means you need a "hard parts" rebuild, which will still be cheap.
This? Although I am one of the more mechanically inclined in my circle of friends, I would be having the Mechanic do this job as I don't want to risk screwing up anything related to Transmission. What would be a rough ballpark figure for this repair, including parts and labor? Will help give me an idea of what to expect. Also, I haven't checked the transmission fluid in at least a year. How often should that be checked/changed? Is it something the Mechanic will have to or should do when he does this repair? Thanks for your prompt replies, guys.
 

JasonTL

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Corvette Owner, I did read that as a possible reason, but I recently had the exhaust all the way back to the engine re-done. Nothing in that system should be having any issues. I found This video about the 4L60E (700R4, right?) transmission and the issue for number 2 is EXACTLY what I am experiencing. This video reminded me that I have been experiencing issues with lack of power in reverse for quite awhile now. I should've realized that meant a more serious tranny issue. So if this is the case, which it seems like it, here's my next few questions: What would a ballpark figure for this repair be? Are there any other things which should be checked/replaced during this repair to prevent future issues? Since the tranny would be taken apart it would seem logical to check out other worn parts at the same time.
 
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Originally Posted By: JasonTL
Corvette Owner, I did read that as a possible reason, but I recently had the exhaust all the way back to the engine re-done. Nothing in that system should be having any issues. I found This video about the 4L60E (700R4, right?) transmission and the issue for number 2 is EXACTLY what I am experiencing. This video reminded me that I have been experiencing issues with lack of power in reverse for quite awhile now. I should've realized that meant a more serious tranny issue. So if this is the case, which it seems like it, here's my next few questions: What would a ballpark figure for this repair be? Are there any other things which should be checked/replaced during this repair to prevent future issues? Since the tranny would be taken apart it would seem logical to check out other worn parts at the same time.
Last two 4L60E rebuilds I had done (my current and previous GM trucks) were right around the $1,500 ballpark including labor and tax, but I had quotes from the $1,250 to $2,000 range on the last one. I would guess the 700R4 would be slightly less expensive. If this is the original transmission, at 209k, IMO it is time for a rebuild anyway.
 
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Powersource has some of the best remanufactured transmissions in the business, but only go back to 1990 model year. Not sure if they are identical 88-90 but here's the pricing. http://bestrebuilttransmissions.com/ This is slightly more expensive since a shop will charge you a few hundred for installation but you know everything was replaced. With a transmission shop you never know if they replace the minimum amount of parts or not. http://bestrebuilttransmissions.com/GMC.htm If that's not an option.. Try to find a reputable transmission shop and ask them questions to feel them out about their process. The shop will install all new fluid as part of any rebuild but most shops know nothing about fluid and use a cheap mineral based dex/merc. That is fine for the break in period but I would quickly replace it with synthetic.
 

JasonTL

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Originally Posted By: Trav
I hate to ask the obvious but have you checked the fluid level.
I hate to answer the obvious...
Originally Posted By: JasonTL
Also, I haven't checked the transmission fluid in at least a year. How often should that be checked/changed?
I know, shame on me for not checking it regularly. I check the oil, brake, and coolant but not the Tranny fluid. I guess because I'm somewhat afraid of it because it requires the engine to be running, right? Never really been sure exactly what 'The Right Way' to check tranny fluid is. Perhaps someone could give a brief rundown of that and I can check it tomorrow. Though unfortunately I don't think that will fix this issue., it probably would've helped prevent this one. From some research I've been doing today it looks like this will be at least a $900-1500 job...
 
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How i check mine, I get it up to temp or after work and leave it running and pull the stick and wipe it and put it back in then pull it out.
 
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Checking the tranny fluid is super easy. Simply drive vehicle and bring engine and transmission up to operating temp, (for example, on your way to work). Once you arrive at destination and engine and tranny is up to temp, park on level area, engage the parking brake and pop the hood. With the engine still running, pull the tranny dip stick and wipe clean. Reinstall dip stick and then remove and find the fluid level on the dip stick. Act accordingly, (either add fluid if needed or don't add if at proper level). Close hood, turn off engine, disengage parking brake - done. While you're doing this, be sure not to be wearing any loose clothing, (neck ties are a quick route to a painful trip to the ER). Secondly, when you check the fluid, note the color and smell of the fluid. Is it dark, does it smell burnt? Good luck
 
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Question: Would this be the 700R tranny or would it be either the 350TH or the 400TH? Either way, as has been said, they are they cheapest and easiest to work on and rebuild.
 
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One more thing - when you had your exhaust system redone, did they replace the cats? It could be you got a complete exhaust system rebuild from the cats back to the end of the tail pipe so that now, you are still running on the original cats which could be clogged. A quick and easy check would be - does your trouble happen immediately upon starting the vehicle or does it "develop" after a few miles? Does it go away after the vehicle has sat a few minutes, only to develop again down the road, or is the problem constant from the time you start the vehicle? If it "develops" and gets worse as you drive, it could be a clogged exhaust system. If it happens from the get-go, I would lean to tranny problems.
 

JasonTL

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Thanks guys, I will be sure to check it accordingly soon. It should be the original Tranny, which I think is the 700r4. Is it safe to drive it in 2nd gear until I get this repaired/rebuilt? I still have reverse, just not very strong reverse. The inability to switch from 1st while in Drive/OD is what brought this issue to the forefront. I have a half mile country driveway so I can't really do over 25 on it anyways. Once I reach the road however and try to accelerate to normal speed it fails to switch out of 1st.
 
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I would be fearful of breaking down with a failing tranny. It might get you to your destination and then again, it might not. If it is indeed the transmission, you are running on borrowed time. If you plan on driving it for a while in this condition, get AAA and a cell phone.
 

JasonTL

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I do have a cellphone and USAA and would rather not drive it this way for long, but $1500 isn't exactly in the budget either :-/ I'll have to see how I can arrange transportation and schedules and call my mechanic soon to get his input and an idea the price for him to fix it. Thankfully this isn't the only vehicle in the family, it's just my only vehicle, heh. I appreciate the responses y'all. It's nice to know I can ask this forum almost anything and get a good idea of the issue within a day's time.
 
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You're probably right to be planning for a rebuild. But before you keep driving it like this, check the fluid level and top it off if needed. Also, Rand's comment (the first reply) got me wondering if this vehicle has the adjustable TV cable. Can anybody answer that? If it does, that's another easy adjustment to try before limping it to a mechanic. I had a 1987 Caprice, carbureted, with the 700. Adjusting the TV cable would change shift firmness. I couldn't say whether it would have any bearing on your problem, which sounds like slipping. It was an easy adjustment, though--hold down a button, pull the throttle open all the way, and it's done. Good luck, and let us know what you find out.
 
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Has the transmission fluid ever been changed? If you have the original Dexron in there it's probably sheared to water. A drain and fill could buy you some time. If it's getting a rebuild anyways, additives are definitely on the table. Some sort of thickener might get you extra pressure to limp back and forth.
 
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