Diesel Vibration / Resonance Problem

Tesla · 23 Jun 2011 at 07:33

Morning all,

I have bought a new car, an 08 Mondeo 2.0 TDCi. I will post it up when I am home (working away).

I am pleased with the car except for one issue. There seems to be an excessive amount of vibration and/or resonance.

The vibration is not linked to road speed, it's linked to engine speed and changes at different RPM's. It exists in all gears, including neutral and dipping the clutch has no effect. Also, holding the car at 3.5k seems to create a nasty resonance, sounds like when the baffles in an exhaust start to fail. This is particularly bad in 3rd gear and 3.5k = around 40-50mph so easy to reproduce.

Obviously, my initial thoughts are "not the DMF already". My plan is to drive the car for 2 years, around 100k miles at my current use so I am expecting to change the clutch and DMF in this time frame so it wouldn't be the complete end of the world. However, I have been Googling DMF failure symptoms and it doesn't appear to have any.

Could worn engine mount(s) cause this sort of vibration?

Could a faulty exhaust cause vibration to be felt through the car and steering wheel?

I'm really not to sure where to start with regards to testing components and checking. Perhaps it'd be best to put it into Ford for diagnostics?

I did hire a Mondeo 2.0TDCi for a week before buying this one to ensure I liked how the car drove and I cannot recall the hire car vibrating, in fact I recall it being quite refined.

(I'm fairly competent with spanners but never owned a complex diesel before).

It's a bit gutting when you think you have found and bought the right car to then discover a problem with it.
I searched for a nice example for 6 weeks which adds a little insult too. I just didn't notice it as apparent on the test drive.

Thanks in advance.

EDIT - The car seems to be performing fine. Pulls smoothly and no smoke.

Tesla · 23 Jun 2011 at 07:40

Perhaps worth noting is that the only thing this car has had outside of routine servicing is a PAS pump. The previous owner did get the car looked at a few weeks after fitting due to excessive pump noise. I don't know what was done to resolve this. The Aux drive belt isn't jumping around though and the PAS pump seems quiet to me.

Firestar_3x · 23 Jun 2011 at 09:08

Soon as i read the thread title i thought Engine / Gearbox mounts.

Give them a good check over.

Tesla · 23 Jun 2011 at 10:20

I was hoping you'd reply Mark as I recall you've diagnosed and fixed most common diesel issues with your Passat over the past couple of years.

What shall I be looking for when checking engine mounts? I've replaced a gear box mount before and could visually see the rubber had split.

Phil W · 23 Jun 2011 at 10:23

Have a look on Ford Wiki, there's a topic on there on how to fix a vibrating noise at certain RPM's, I'm sure it's something to do with the airbox or a pipe connecting to it rubbing on something.

/edit - I notice it's an 08, I was thinking MK3 but it must be a MK4?

Firestar_3x · 23 Jun 2011 at 10:25

I've got a petrol mate but quite a lot of the stuff is the same, not sure if this is the best way of checking but it's how i do it:

- Give the engine a shake and look for excessive engine movement.
- Start the car and rev it out of gear, look for excessive engine movement.
- Visually inspect each mount, looking from cracks / splits / metal back plate which has come away from the rubber.

It's an easy check to do, your biggest issue is access, i use a dentists mirror which works great.

Tesla · 23 Jun 2011 at 10:38

Oh yes, for some reason I always thought it was a Diesel. Oops!

The vibration I am feeling is quite a high frequency, not like the low frequency "shake" on a bus.

I am mega-busy at the moment and then away for a few days down in Cornwall so I may just put it into a dealer and take a loan car. I've hardly ever used a garage before but just don't have the time over the next few weeks to spend a day tinkering with it.

Tesla · 23 Jun 2011 at 10:39

Yes, it's a Mk4. It's not a vibrating noise, just vibration. At least I know the dash is screwed together properly as no rattles even at resonant frequencies.

I have taken a couple of pics ready to update my "spec me" thread from a couple of months back but I don't have my USB cable with me and not home until Friday.

In Halfords they sell a small mirror on the end of a flexible arm so I may pick one up.

Tesla · 23 Jun 2011 at 11:28

I just called my local Ford parts desk and the chap said one of the mounts seems a common fault as he stocks and sells a fair few. This common-fault mount is only £21ish and the other mount about £30.

I am hoping it is the mounts as at least it's cheap parts and low labour costs!

Tesla · 24 Jun 2011 at 08:56

Just thought i'd add that for it's first MOT last month it failed on CV boot split, both were replaced.

Would excessive engine play cause the CV boots to split do you think?

I haven't noted any "clonking" or similar so have a small doubt over mounts.

4T5 · 24 Jun 2011 at 09:05

2 things I would do.
Get somebody else to sit in the drivers seat & bite the clutch up, The Torque will move the engine & you'll see whether it moves excessively pointing towards a mount.
2nd thing would be to get somebody to rev the car as I put my foot on the tail pipe to see if it's the exhaust rubbing, Has it had the exhaust fixed/replaced recently ?