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Vehicle: Mazda 3 (2014) 2.2 D Sport Nav SKYACTIV-D Manual Transaxle VIN: JMZBM642611171664 Mileage: 140,000

Problem: Severe Vibration When Engaging Clutch Biting Point at 750 rpm.

Problem Summary: Vibration is Apparent Moving-off from Standstill in 1st Gear and Reverse. Vibration is Also Apparent Manoeuvring at Low Speed into a Driveway or Parking Spaces etc. Vibration is Detectable Moving-off in Second Gear at 1,200-1500 rpm and Occasionally Changing Down from 3rd to 2nd Using Synchromesh.

If anyone can shed any light I’d be most grateful. There is a detailed history below if you’d like to read on.

Vehicle History: The vehicle has been meticulously maintained since new by Mazda main dealer: Super-diesel fuel Oil changes every 6,250 miles It has wanted for nothing.

Mechanical History of Problem: Thu 14-3-19: 63,153: Laboured knocking effect when starting engine cold.

Sun 26-5-19: 66,230 miles: ?Clutch-related, cyclical ‘knocking’ sound when clutch is let up slowly at low revs, plus noisy clutch at idle until clutch depressed.

The knocking effect above came and went over many miles but slowly worsened.

6-12-22: 137,472 miles: DMF/Clutch assembly replaced. Mazda declared that DMF almost certainly the culprit and definitely out of spec as an original part at this mileage.

Upon return there was a floor pan vibration and the clutch pedal was out of adjustment and there was a vibration engaging the clutch.

Mazda immediately replaced the clutch, stating it would all be new again as it’s a ‘fit-once part’. This fixed the pedal and the floor pan vibration but the vibration engaging the clutch remained. I returned with the car and stated my dissatisfaction but was given a range of suggestions that, “…these cars do tend to vibrate etc.” As I intended to keep the vehicle I undertook a series of investigations with other garages and also replaced all of the engine mounts over a period of 9 months. Each replacement made a noticeable improvement to the ‘tightness’ of the engine but did nothing to improve the vibration. All four garages I had examined the car suggested it was the clutch.

I spoke to LUK, the clutch manufacturer who were amazed Mazda weren’t using the self-adjusting clutch tool to fit the clutch as this would mean it could be taken on and off many times, as it is in no way a ‘fit-once’ part.

I wrote to Mazda with my battery of information and they replaced the clutch for a 3rd time, making twice at their expense, with oversight from the manager.

After 3 days of attention, the clutch still vibrated. So they undertook some further investigation in the form of a compression test and leak down tests. These showed that all cylinders were at or below the minimum 261 psi at 180rpm.

Their official diagnosis is that the low compression is causing the vibration at low revs.

However…. Two weeks after accepting back the vehicle the master warning light came on and briefly, the oil light. Mere seconds later I shut down and coasted to a halt. The long and short of this was that the Skyactiv-D 2.2L curse of leaking injector washers was to blame and the oil strainer was replaced, injectors cleaned and washers replaced etc. No further compression test was performed.

With the vibration persisting I took the car to a firm of vehicle engineers and asked them to assess the vibration problem. This is ongoing due to lead times with booking in but the investigations to date and results are:

  • Initial use of Forté Advanced Formula Diesel Treatment and a hot engine drive at 4-5000 rpm. This noticeably improved fuel consumption by 6 mpg but made no difference to the vibration.

  • With the injectors seals now fixed a compression test was performed which showed excellent compression throughout all cylinders, completely invalidating Mazda’s theory. This made no difference to the vibration.

  • The vehicle is smooth, powerful, has never had flat spots, does not use oil, produces clear exhaust, has never had a DPF problem and does not use coolant.

  • The exhaust pipes are clean and an emissions test produced a result of “Too clean to test.”

  • We will shortly do a borescope check but personally, I don’t expect that to reveal anything.

  • On these cold -2°C mornings the engine strikes up immediately.

Nothing about this seems to suggest to me that this vibration has to do with poor compression, although I am no expert.

The vehicle will vibrate like hell engaging the clutch at 750+ rpm but then drive on nil throttle up an incline as smooth as silk at 700-750 rpm, under load.

My Request for Help: Thank you, if you have read this far!

Would anybody have any suggestions as to what could be causing this vibration? It has persisted through (presumably) three new DMF/clutches, new engine mounts and improved injector nozzles from cleaning and improved compression from fixing the injector seals.

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  • Has anyone checked your motor mounts for wear or excessive softening? If this engine has a torque snubber or damper, has this been checked or replaced? (On a VW diesel they call this a "dogbone mount", and if it's worn out, you get the vibration you described.)
    – MTA
    Dec 4, 2023 at 20:42
  • Hi and thank you for replying. I have replaced all 3 engine mounts and did so after the first clutch replace. Regrettably this made no difference to the vibration, although I noticed a tighter feel to the engine. The car does not have a damper/pendulum mount. 😏
    – Aletheia
    Dec 5, 2023 at 0:22

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I have the same problem. On first, sorry for my bad writing, English it's not my native language. On Dec 22, 2023 i have my first clutch set replacement on my Mazda 6 (2015) by Mazda dealer. After first replacement, I noticed the vibration, same as you. I bring it back to Mazda, and they put another new set (at least they say so). But that didn't solve the problem. Now they said that i should drive for 2-3000km, to see if it settles, or it will show the problem. For now, I didn't see any improvement, except that's I'm puting a little bit more throttle on starting, that eliminates the vibration. I also think it was a engine mounts, but inspected them in Mazda, and said that they are ok. Now I believe them, after reading your post. Except bad DMF (maybe is production fault) I don't know what else could be. I think I will try to put my old clutch set (they said that they still have it), to test is it a problem with new clutch, or something else. Where are you from, if I may ask? I'm from Croatia. Maybe its a problem with new clutch set distributed to our countries.

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  • Hi Tihomir, I am in the UK, England. As I think I said in my post, Mazda told me last that the vibration was due to poor engine compression. They said my cylinders were all around 220 psi and the minimum is 261. They also said they did a leakdown test and the cylinders were 40-60% leakdown! I have had independent tests done and the compression is 340-360 psi and the average leakdown confirms this as it is just 2.7%.
    – Aletheia
    Mar 9 at 23:47
  • So, the engine is in good health. The same engineering company is going to replace the clutch/DMF and release bearing etc again this Thursday/Friday 14th/15th March and inspect it all on the vehicle and on the bench and then fit another LuK clutch/DMF kit. I will let you know if this cures it. Like you, I think there must be a bad batch of clutch/DMFs or some very poor fitting going on.
    – Aletheia
    Mar 9 at 23:47
  • I also didn't think that is a engine problem. Because if it is, the vibration would occurred while driving, not just when I engage the clutch. So I'll wait for you to change another set this week. To see, is it a bad batch of clutch/DMFs (distributed all over Europe??), or some mechanic mistake. Please let me know if new LUK set of clutch solves the problem. Then I will do the same. Thanks for info. Mar 10 at 23:05
  • I certainly will let you know.
    – Aletheia
    Mar 12 at 8:10
  • Dear Tihomir Well, I have not got a straightforward answer for you. * The clutch/DMF was found to be faulty. On the flywheel side, the friction plate was shiny on its outer rubbing ring only, the inner ring looked unused. * The DMF itself showed heavy signs of heating and judder marks around 2/3 of its outer edge and nothing on one third. Its central bearing was shot. There was a lot of debris around the plain bearing ring and parts of ‘o-ring type’ debris could be pulled away with tweezers.
    – Aletheia
    Mar 24 at 15:32

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