159 1.9 JTD Shudder Under Acceleration
I'm driving a 2006 159 1.9 JTD. I've only owned the car (my first diesel) for just over a month and it's my first Alfa.
About a week ago I noticed that my car was giving a slight vibration under hard acceleration. If I accelerated, foot to the floor, in 5th for example (starting from around 1800 - 2000 rpm) there was a noticeable but slight vibration through the pedals and steering wheel. My initial thoughts were that it seemed engine/gearbox related rather than wheel/axle.
Then this week as I was driving on the motorway I got a much more severe vibration, more of a shudder through the whole car. This was at 120 - 140 kph in 6th. I thought that this was coming from the passenger front side and it was making a noise not unlike a totally knackered wheel bearing, a loud deep hum, but it was cyclical; 2 seconds on, 1 second off.
I got home and hadn't driven the car again until today. Everything seemed fine initially, took it for a quick motorway spin after checking tyre pressures (which were a little low on passenger side). I didn't push it but everything seemed good, so off I went on a longer motorway journey. 10 minutes in and I could feel and hear it creeping in again. It got progressively worse over the next 10 minutes and plateaued from there.
I tested it a bit more and discovered:
It is a severe shaking and shudder through the whole car that is fairly constant.
It is almost certainly coming from the engine/gearbox.
I can feel it through the steering wheel, pedals, seat.
It only occurs under acceleration. The harder the acceleration the worse the shudder becomes. It does not happen/ goes away if I press the clutch or even when I'm braking.
Using cruise control it was obvious that when the car was going uphill the shudder worsened and eased off or almost disappeared on level surface or going downhill.
There is a knocking noise and sensation with it not unlike what you would feel from an ABS pump kicking in, fast thud sounds, not very loud.
I noticed that the needles on the rev counter and speedo were jumping very slightly all the time, this was with cruise control on. Maybe 2mph jumps every second or so and similar on rev counter. This might be normal, haven't noticed before.
Has anyone ever experienced anything like this? I'd be grateful to anyone who can point me in the right direction as I'm pretty concerned about it!