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Tachometer Getting Up to 7.5k RPMs When Accelerating
Happy New Year all! I recently became the extremely proud new owner of a 2014 GLK 350. Everything is perfect, but when I accelerate hard (especially when passing), the indicator on the tachometer can go as high as 7.5k RPMs. My local dealer (from whom I did not purchase the vehicle) said that this is normal operation, so I've tried to not let it concern me, but it would give me much greater peace of mind if fellow owners could weigh in and let me know if they agree that this is normal operation. 7.5k is well within the red zone, so that just doesn't make much sense to me.
I see in your photo the green E is lit, does your trans shift different (higher) when set to the red P, mine won’t shift anywhere near that in E mode . Your beating your glk to make it shift like that. It probably needs a service , I just did my trans fluid - filter because it was slipping at 60,000m , when you buy things used often there are issues, a fluid drain and filter is a smart thing,
I don’t let my glk go to 6.5 or7.5, is it set to E or P,
it’s in Eco mode when this happens. I haven’t tried Sport mode because I know that’s supposed to lengthen the time between shifts, which seems like it would only make the problem worse.
I see in your photo the green E is lit, does your trans shift different (higher) when set to the red P, mine won’t shift anywhere near that in E mode . Your beating your glk to make it shift like that. It probably needs a service , I just did my trans fluid - filter because it was slipping at 60,000m , when you buy things used often there are issues, a fluid drain and filter is a smart thing,
Thanks, but it’s had as much maintenance service as it needs - including new fluid and filter for the transmission. I try to watch the tach and not get into the red zone, and will be doing so even more carefully after all of these replies...
I meant The green E and the red S for sport, p was a mistake. I just checked my 13 and it shifts at about 3500 -4000 In sport mode, try it in sport , but 7500 is way to high rpm. Why not take it to someone else, is the dealer that’s diagnosing it as ok the one that sold it to you ? My dealer in Chicago is a big fat crook, they won’t fix anything under extended warranty , probably because they kept the cash and would have to pay for the repairs .
This sounds like an issue you need to fix soon - before something goes bang.
How is your transmission shifting: harsh shifts, shifting at the correct rev points? What gear are you in when the engine hits 7.5K? How are the shifts when you shift manually?
You mention that you've had a fluid change, that would have been my first guess. Is the fluid level correct? Other possibilities might be the solenoid or the tranny speed sensor (both should throw a code but...).
I would get an MB-specific code scan to see if anything shows up. In the meantime drive your car as little and as gently as possible and use manual shifting to limit the revs.
Good luck
One other (extremely) off-the-wall thought. Does the engine sound as if it's doing 7.5K? It should sound and feel really strained. If not, maybe your tach is giving you bad info.
I honestly dont know why your engine will shift at 7.5. i wont say impossible, but i think it not normal. Your engine is m276, and is rated at 302hp @ 6k rpm. Do u have any video or pictures to show ur glk shift at 7.5 k? Even the V8 NA c63 amg, it only shift at 7k max. So imagine your normal glk shift at 7.5k. for sure something wrong.
I meant The green E and the red S for sport, p was a mistake. I just checked my 13 and it shifts at about 3500 -4000 In sport mode, try it in sport , but 7500 is way to high rpm. Why not take it to someone else, is the dealer that’s diagnosing it as ok the one that sold it to you ? My dealer in Chicago is a big fat crook, they won’t fix anything under extended warranty , probably because they kept the cash and would have to pay for the repairs .
I will give that a try, thanks! It’s not under warranty and wasn’t sold to me by the dealer I took it to.
This sounds like an issue you need to fix soon - before something goes bang.
How is your transmission shifting: harsh shifts, shifting at the correct rev points? What gear are you in when the engine hits 7.5K? How are the shifts when you shift manually?
You mention that you've had a fluid change, that would have been my first guess. Is the fluid level correct? Other possibilities might be the solenoid or the tranny speed sensor (both should throw a code but...).
I would get an MB-specific code scan to see if anything shows up. In the meantime drive your car as little and as gently as possible and use manual shifting to limit the revs.
Good luck
One other (extremely) off-the-wall thought. Does the engine sound as if it's doing 7.5K? It should sound and feel really strained. If not, maybe your tach is giving you bad info.
Thanks! The shifting is fine, super smooth and usually at good rev points, aside from the fact of course that when accelerating hard, it will often go as high as 7.5k rpms before it shifts. I had it serviced at MB of CO Springs, so I’d assume it was filled correctly (though I don’t believe there’s a dipstick for that, but regardless the issue was the same before and after the service), and I know they did a scan especially for MB codes. It does sound rather strained at 7.5k. Thank you for the specifics on what it might be and the advice!
I honestly dont know why your engine will shift at 7.5. i wont say impossible, but i think it not normal. Your engine is m276, and is rated at 302hp @ 6k rpm. Do u have any video or pictures to show ur glk shift at 7.5 k? Even the V8 NA c63 amg, it only shift at 7k max. So imagine your normal glk shift at 7.5k. for sure something wrong.
Thanks - that’s what I thought but the dealer told me otherwise. After these replies I’m certainly going to be shopping a second opinion. I don’t feel the need to show this with a video, especially since doing so would risk (further?) damage to the engine. The service tech at the dealership replicated the problem, so I’m confident I’m not misinterpreting anything.
Last edited by RockyMtnBenz17; 01-05-2021 at 11:43 PM.
Wait, is it ALWAYS revving up to 7.5k rpms before it shifts? Can you control the gear shifts with paddles? If so, I would do that and not let it rev up that high.
Even in sporty driving, there's no reason to rev it past 6k rpms if you can help it. Either it's tuned somehow without you knowing it (previous owner) or something's up with the electronics: could be the ECU that controls the shift points or the instrument panel controller(s) which may be on separate CAN gateways (ie, individual computers).
Wait, is it ALWAYS revving up to 7.5k rpms before it shifts? Can you control the gear shifts with paddles? If so, I would do that and not let it rev up that high.
Even in sporty driving, there's no reason to rev it past 6k rpms if you can help it. Either it's tuned somehow without you knowing it (previous owner) or something's up with the electronics: could be the ECU that controls the shift points or the instrument panel controller(s) which may be on separate CAN gateways (ie, individual computers).
Good luck.
No, thank goodness, just when I’m flooring it essentially (I live in the mountains though, and if I am passing I typically need that power, which is actually a big reason I upgraded to a V6 lol). The paddle shifters do work to my knowledge...I don’t understand how those work though - I’ve never driven a manual or anything with paddle shifters. I will try googling my way to understanding, but if anyone has any advice about how to use the paddle shifters to prevent it from getting over 6k would be much appreciated. I’m mostly wondering if I need to shift up or down (I think down??), and am also wondering how I’d get it to go back to operating as an automatic transmission after I’ve shifted up/down. Thanks again everyone, such a great and supportive community!
Pretty easy to operate the paddles. Right one goes up through the gears, left one goes down through the gears.
You shift up as you gain speed, shift down as you slow down. You can also shift down to create engine braking (useful for long steep hills).
The paddles will momentarily place the transmission into “manual” mode, where you will HAVE TO change each gear, but will resume full auto if no further input is received (I think 30 seconds tops).
Try it out when you get a chance, it’s not bad at all.
You can keep the revs down by going down one gear manually (like from 7th to 6th) before you start passing, and then shift up back into top gear at your desired RPMs. I think 4-5k is probably more than enough.
I do it all the time on Moose and he’s a diesel, which means he revs at much lower RPMs and 4.5k is his redline basically.
My wife's GLK has a button to cycle between E (economy) S (sport) and M (manual). The selected mode shows on the gauge cluster. Oddly enough, her owners manual makes no mention of it.so you may or may not have this. The button sits between the seat heater buttons. When "M" is selected the temporary nature of up/down shifts that andreigbs mentioned is over-ridden and manual mode is more permanent (sort of). The car will downshift itself when you come to a stop and will upshift to protect the engine (in your case not so much). Seems pretty redundant when the paddles will interrupt the tranny on demand but it is an MB after all and they do stuff "because we can".
Pretty easy to operate the paddles. Right one goes up through the gears, left one goes down through the gears.
You shift up as you gain speed, shift down as you slow down. You can also shift down to create engine braking (useful for long steep hills).
The paddles will momentarily place the transmission into “manual” mode, where you will HAVE TO change each gear, but will resume full auto if no further input is received (I think 30 seconds tops).
Try it out when you get a chance, it’s not bad at all.
You can keep the revs down by going down one gear manually (like from 7th to 6th) before you start passing, and then shift up back into top gear at your desired RPMs. I think 4-5k is probably more than enough.
I do it all the time on Moose and he’s a diesel, which means he revs at much lower RPMs and 4.5k is his redline basically.
Thank you a ton, this is super helpful. Sad to see that I can’t just quickly put it back into auto when I’m done passing, but I can see myself enjoying using them once I get used to it!
My wife's GLK has a button to cycle between E (economy) S (sport) and M (manual). The selected mode shows on the gauge cluster. Oddly enough, her owners manual makes no mention of it.so you may or may not have this. The button sits between the seat heater buttons. When "M" is selected the temporary nature of up/down shifts that andreigbs mentioned is over-ridden and manual mode is more permanent (sort of). The car will downshift itself when you come to a stop and will upshift to protect the engine (in your case not so much). Seems pretty redundant when the paddles will interrupt the tranny on demand but it is an MB after all and they do stuff "because we can".
01-03-2021, 05:33 PM
