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My car won't go over 40 mph

I have a 1998 Mercedes Benz that won’t go over 40 mph.
For some reason it is not shifting to the next gear. I was driving on the highway going 80, when the car locked up and slowed my car down to 40. It’s been a month and it still won’t go over 40.
I took it to a transmission shop and they said to rebuild it at $3000. If you guys know any other options or solutions please let me know.

Solution as I see it is to either fix the current issue ( transmission) or dump it and get another reliable car

There are failure modes in automatic transmissions that don’t require the transmission be rebuilt. Could just need replacing a solenoid. If you don’t believe what the trans shop told you, the first step is to check the transmission fluid level and fluid appearance. Has that been done? there are other reasons a car won’t go over 40 mph that don’t involve the transmission. The engine diagnostic codes would be the clues why for those.

If a transmission shop says your transmission needs to be rebuilt, it probably needs to be rebuilt.

There’s nothing any of us can do to change that except recommend you get a second opinion.

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There are no codes on the car. The check engine light is not even on. And yes I checked the fluid levels as well as the color.

I presume you mean there are no engine codes. There could be transmission codes that only a high end or Mercedes’s code reader has access to. But given no engine codes, looks like you are looking at some transmission diagnosis and repair there. Ask at the shops around town who’s the best Mercedes or German car transmission shop in the area. Ask who’d they’d take their own Mercedes to. There always tends to be one transmission shop that is rated tops, heads over heels above the others, by the local mechanics. You don’t need to use a dealership for a 98, unless the dealership is who turns out to be the most highly rated by your informal polling. If you have a very German-car knowledgeable auto parts store , that’s another place to ask.

OK, wait you were traveling at 80 mph and something happened in the transmission that actually locked up and slowed the vehicle down violently? Did this issue happen like that? Or was it after the highway you came to a stop and then the vehicle would not shift into the higher gears?

If it was a violent downshift type of thing, I really dont know what that could be. What happens from a dead stop… You would be in 1st… do you get 2nd gear? 3rd? Or are you stuck in 1st? Can you manually move your shifter and get into different gears? Does your shifter feel different in resistance or lack thereof?

Explain the actual failure mode a bit more. Not being able to go over 40 is a bit too vague… Take us through it from a full stop. There are solenoids in the shift body of your transmission…they may have had a failure and have locked you out of gears…the gears could still be there and healthy and waiting to be enlisted…but the solenoids that control them and the 1-2 shift or 2-3 or 3-4 shift event are out to lunch. I have repaired many Honda transmissions by replacing their externally mounted shift solenoids…its nice when they are external…some are internal and not as simple to replace.

Many transmission “failures” aren’t as advertised. Shift solenoids are a common failure and will make you think the trans is hopeless when in reality its a small relatively inexpensive repair part that is needed. So don’t despair just yet.