Hi,

 

I recently bought a used 2017 Skoda Mk3 1.0tsi DSG that's run 117000 kms. I'm now observing vibrations through the steering wheel and the seat at a specific RPM range (2000 to 3000 rpm) across all gears including neutral. When I drive at around 100kms/hr, I'm usually at the 2000-3000 rpm range in the 7th gear, so the vibrations are just always there at this speed range. If I want to avoid the vibrations, then I'd have to shift lower to the 6th gear so that it's beyond 3000 rpm, however, then the engine feels like it's struggling. At the neutral position without depressing the accelerator, there are no vibrations, however, if I depress the accelerator to be at 2000-3000 rpm range, then again there are vibrations. 

 

Additionally, if I accelerate from standstill on a slope, then the vibrations are significant (the car almost shudders) before becoming normal.

 

Any idea what could be the reason? I've read that uneven wear on tires might be a culprit but since this happens at a specific rpm range, could I eliminate tires as a problem? Other than tires, I'm reading that axles, suspension, engine or transmission could be a problem. That's a wide range of parts, and I guess it can be equally difficult for the service person to isolate the issue, and give me a guarantee that the vibrations will be gone once he fixes something. 

 

I'm visiting the garage next week, but I'd like to get your opinion on this so that I can speak with the service person more knowledgably. 

 

Thanks!

 

Hello, welcome to the forum. Normally I'd suggest wheel balance issues for this, but from your further description, possibly a drive shaft problem or engine mounts.

Your engine should not sound as if it is 'struggling' in 6th gear at 100Km/hr - do you actually mean you think it's over-revving?  - at that speed, revs should be well under red line and engine should feel and sound fine. SWMBO's 1.0 Fabia always feels to me like it needs to be in a lower gear, especially below 50-60MPH. 

Edited 8 February, 20242 yr by Warrior193
added information

Engine mounts?

Thanks @Warrior193! I've come across mentions of engine mounts potentially causing vibrations, but I was under the impression that if they were the culprit, I'd feel vibrations consistently rather than just at specific RPM ranges. Am I wrong? I'll definitely have that checked too.

 

I'll make sure to have the drive shaft checked.

 

About struggling in the 6th gear, that's correct -  I feel like it's over-revving.

 

Overall, from what I've read, it feels like a very difficult problem to isolate and fix, and I'm thinking if I should even invest the time and money to fix this instead of simply selling it back (for a loss of course 😞). I don't want to be in a position where I spend a thousand bucks to fix it and still don't have it resolved or for it to come back later. Any thoughts?

As @Warrior193 suggested, I would have gone with wheel balance at the mention of it vibrating at a certain speed. However as you suggested that it went away when off throttle, I think I would be looking at a C.V. joint being worn and throwing a drive shaft out of kilter as well.

 

One check you could do yourself though would be check your wheel nuts are tight. You just never know...

See what the inspection throws up, do you have access to a mechanic / garage you trust? One quick test you could do to check for wear in the drive-shaft CV joints is to drive round a circle in both directions at full lock and listen for any knocking noises.

Edited 8 February, 20242 yr by Warrior193
correction

At a guess, it could be simply misfiring (plugs or coilpacks) - check for pending error codes

or in the early stages of DMF (dual mass flywheel) failure.

Edited 8 February, 20242 yr by xman

Thank you very much for all your comments! I have the service appointment on Tuesday. I'll share how it goes. 

Made a trip to the garage today!

 

First off, the mechanic took the car for a drive and confirmed there's indeed some vibration in a specific RPM range (it's actually between 1500-2500 RPM and not 2000-3000 RPM). It was a bit of a relief, as I had wondered if I was just being overly sensitive about it!

 

After inspection, it seems the engine mounts and tie-rods are in good shape. However, there's noticeable play in the inner CV joint connecting from the transmission (if I'm not wrong) to the right wheel. The mechanic suggested this could be the culprit behind the vibrations, but he's not entirely certain if fixing it will resolve the issue. For contrast, the other CV joint is completely solid with no play whatsoever. The mechanic, who also owns a Skoda Octavia, plans to check the play in his own car to gauge if the amount in mine is significant enough to warrant replacement. He also recommended getting a wheel alignment and balancing done regardless of the CV joint replacement.

 

Now, I've got a few questions:

• Is it normal for CV joints to have any play at all? The left one in my car was rock-solid, while the right one had noticeable play. But I'm not sure if it's excessive or within the normal range. There is a bit of clacking sound when I move it with my hand and the play is probably 2mm - 4mm end-to-end. (I should've taken a video. Missed that, sorry!)
• Is there any test that can help me zero-down on CV axle being the cause for vibrations?
• Do you have any idea about the cost of replacing the inner CV joint, and are there any reliable aftermarket brands worth considering? I assume the original part could be significantly pricier than aftermarket alternatives, and I'm hesitant to shell out too much money if I can avoid it.
• Are the terms 'drive shaft' and 'CV joints' essentially interchangeable, referring to the same component? If so, do the two CV joints collectively form the drive shaft?
• If the issue is wheel-balancing, shouldn't the car vibrate at any RPM and not specifically in the 1500-2500 range? 

Edited 13 February, 20242 yr by neo911

I'd suspect that the play in the right CV joint will be found to be the culprit.

In my experience, the body of the CV joint is an integral part of the drive shaft.

Also in past experience - although not recent - it was common, particularly for an out of balance front wheel, for a vibration to manifest at a fairly specific rotation speed - probably a harmonic frequency.

 

 

1 hour ago, neo911 said:

If the issue is wheel-balancing, shouldn't the car vibrate at any RPM and not specifically in the 1500-2500 range? 

Yes, nothing to do with engine rpm especially when in neutral.

1 hour ago, neo911 said:

Is it normal for CV joints to have any play at all? The left one in my car was rock-solid, while the right one had noticeable play. But I'm not sure if it's excessive or within the normal range. There is a bit of clacking sound when I move it with my hand and the play is probably 2mm - 4mm end-to-end. (I should've taken a video. Missed that, sorry!)

If the gearbox end mouting flange has end play then it indicates the differential output bearing has collapsed. Yes it happens.

 

If you have the car up with wheels free, grab the drive shafts firmly either side and twist the shafts in opposite directions, repeat in reverse. There should be no flange movement sideways (in/out of the gearbox). If there is, the diff bearings are shot. Consequence can be expensive (new gearbox) the diff is floating side to side and the pinion/crown out of alignment and the crown wheel eventually touches and machines the inside of the housing. Possibly this is the vibration you hear.

 

The classic symptom is a loud clack when going on and off the throttle (Power on/off overrun) which is the diff moving side to side in the gearbox.

 

Edited 13 February, 20242 yr by xman

Sorry about the late response. 

The issue was indeed the right cv joint as @Warrior193 rightly pointed out. 

It's fixed now and running great. Had it fixed for free as it had a 6 month warranty for second hand purchase, otherwise it would have cost close to 1k euros. 

Thanks for all the help