General Shaking at idle

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General Shaking at idle

Jeavons1

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Sep 1, 2018
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'03' Multipla SX, 1.9 JTD 115.

Hi! I'm new to the forum, and I have an issue with my new (to me!) Multipla (JTD 115) which has got a bad case of the shakes!

At idle, which seems to be around 750-800rpm, the whole car shakes quite noisily, regardless of clutch engagement, gear selection, nothing makes a difference to it unless I increase the revs to around 1,000rpm, then everything is fine and quiet again. It seems to be nothing to do with the clutch, fly-wheel, etc.

Once on the move everything is fine (higher revs!), it's just the drop down to idle revs, and everything starts to shake again!

I've read on an Alfa Romeo forum (through a Google search) where someone with a 1.9JTD engine seemed to have a similar problem and it turned out to be a problem with the fuel injectors at low rpm's.

Has anyone here suffered similar or know what I should be looking at?

I'm the proud owner of the Multipla as featured in this month's Practical Classics magazine (in 'Bangernomics'). I'm a friend of the editor, Danny, and it's had a LOT of work done on it over the past month or two in the Practical Classics workshop, including new engine mounts, rear subframe mounts, rebuilt rear brakes, new exhaust, new radiator, new track rod ends, drop links and main gearbox mount. It had a new cam belt fitted last year too.

This isn't my first Multipla JTD, having owned and loved one for ten years until it gave up the ghost. This new Multi is a very welcome addition to the family - but we could all do without the bad vibrations!

Any help would be greatly appreciated!
 
Hi Widemouthfrog!

If it was the crankshaft pulley, would that cause the vibrations at just idle revs, or would that be at all speeds?

Thanks.
 
The full name for the crankshaft pulley is a Torsional Vibration Damper (or TVD). At tickover, the various bits of the diesel drivetrain aren't very good at working in unison. Consequently the auxiliary belt (which runs over the TVD) is trying to provide drive to various ancillaries in a very start-stop way. The TVD has balance weights in it and a rubber coupling between the inner and outer sections in an attempt to smooth out some of this start-stoppiness. In time, the bonded rubber section fatigues and starts to shear, at which point it's no longer very good at smoothing things out. As the engines revs rise, it becomes smoother (courtesy of more power strokes per second) and the TVD has much less to do - the inertia of the crankshaft assembly sees to that.


So the typical symptom of a failing TVD is just what you're seeing (and no doubt feeling!). There are lots of threads on here about it. If it's bad, you may be able to confirm whether it is to blame - take the OSF front wheel and wheel arch liner off and you may be able to see the duff rubber bit on the side of the pulley. It's not always the case that you can see evidence of failure though.


A cheap crankshaft pulley won't be well configured with balance drillings and the rubber or rubber bonding tends to be pants. Buy cheap, buy twice. Or as I said in another conversation about cheap parts on here some time ago - buy once, sell quick :rolleyes:
 
That all sounds about right then! It's a little odd that of all the work that's been done on the car recently, that wasn't touched. I'll investigate further, and thanks for the help!
 
This is a good quality pulley at a good price, and it's in the UK:


[ame="https://www.amazon.co.uk/Dayco-DPV1046-Dampers/dp/B009ZQB30Q"]Dayco DPV1046 Dampers: Amazon.co.uk: Car & Motorbike[/ame]



Bettering this would probably mean going to somewhere like Mr Auto or Autodoc
 
I was looking at the list of pulleys on Mr. Auto and Autodoc's sites yesterday, and a little lost with all the different options, so thanks for the recommendation of this one. I'll get it and get the car booked in (there's a small list of jobs to be done, this is just one of them!).

Thanks again Widemouthfrog!
 
My nose is telling me that the previous owner tried to fix this issue by replacing engine mounts..I’d try running the car with the pulley off... I did it on mine trying to locate a low rev vibration that bothered me for a few years... Also there is a very small locator on that same pulley... I once put it back on incorrectly and it vibrated even worse so that too is a possibilities given it would have been off for cam belt change.
Mine turned out to be injectors. The good news is the injectors don’t need to be coded and are shared with s few other engines, I got a set off an alpha for 50£ popped em in problem solved.
But look at pulley first.
Incidental I thought the correct name was a harmonic balancer!
Marty.
 
Hi Marty,

So you bring me full circle to the Alfa Romeo forum I'd read that talked about checking out the injectors!

I did notice yesterday while at some traffic lights with the windows down, a faint whine, which did make me think it was a belt related issue, but I'll try a few things, but it'll have to wait until later next week now.

Thanks!
 
Update:

Noticed yesterday when I started the engine, the little yellow coil light stayed on for a minute, which isn't normal, although I haven't driven the car much since buying it. Is that significant of the injectors...?
 
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