D24TIC Shakin' all over

[jaydbass]

My N-plate 940 td estate has an interesting characteristic. Starting cold, the engine is fine. Bit smoky perhaps, but fine. However, when the engine is restarted warm it tends to shake quite a bit for a few moments at idle. The car shakes around with it. The revs are kinda reminiscent of a big dog panting (honest) and seem to sit around 500. As i said, after a few moments it settles down. If driven right away, it still seems to take a few minutes to settle as the "panting" is still apparent when sitting at traffic lights etc. I don't know much at all about under bonnet-matters - and had I been able to attend the recent mini-meet I'd hoped for some pointers. I'm wondering if the shaking could be a fuel injection issue, as the car can be quite smoky under acceleration? In saying that, it wasn't driven much for the best part of a year before I bought it (at the end of July) & last weeks Forte treatment seems to have helped a bit with the smoking.
The other thought I had was that the "idler" - which I believe is some kind of belt or pulley tensioner - may need replacing?
Any ideas would be appreciated. Whilst it's a pleasing thought to think of the "big beastie" as a dog happily panting at it's owner's return; it's probably more sensible to safeguard against imminent mechanical failure!
Jay

[RoyMacDonald]

If the idler needs replacing then the Cam belt certainly does, and if either fails they will wreck your engine. Must say I wonder what the bottom of your tank is like if it's been sitting around for a year without use. Try some Millers diesel clean in it for a while.

Roy

[jaydbass]

Belts were all done last year according to the previous owner. Any way to tell if this is the case?

[RoyMacDonald]

Originally Posted by jaydbass

Belts were all done last year according to the previous owner. Any way to tell if this is the case?

Not without looking, and it's not easy to get to.

[jor]

I don't think there should be any reason to disbelieve the previous owner, especially if he owned the car for awhile Jay. If there was something wrong mechanically you'd think it would be a constant problem.
All I can think of doing is to make sure the air and fuel filters are in order. I used have erretic idling at low revs which went after fitting a high flow filter. You've cleaned the injectors. I've not tried Forte but have done it another way - filling the filter with transmission oil (mineral), repeated every so often, as some type of extra lubrication is needed for the pump to compensate for the low sulphur fuel.
The function of the cold start device is to give more fuel as the temp falls, when non functional it just fails to do this, rather than opting to provide extra when it's hot!
Should you get nowhere try a message to Peter Milnes, the register keeper, who may have heard of the problem before.

john

[RoyMacDonald]

Originally Posted by jor

I don't think there should be any reason to disbelieve the previous owner, especially if he owned the car for awhile Jay. If there was something wrong mechanically you'd think it would be a constant problem.
All I can think of doing is to make sure the air and fuel filters are in order. I used have erretic idling at low revs which went after fitting a high flow filter. You've cleaned the injectors. I've not tried Forte but have done it another way - filling the filter with transmission oil (mineral), repeated every so often, as some type of extra lubrication is needed for the pump to compensate for the low sulphur fuel.
The function of the cold start device is to give more fuel as the temp falls, when non functional it just fails to do this, rather than opting to provide extra when it's hot!
Should you get nowhere try a message to Peter Milnes, the register keeper, who may have heard of the problem before.

john

If your using a good quality fuel (not supermarket) it should have an additive package to compenstate for the reduced sulpher.

I'm more concerned about what happend to the fuel that stayed in the tank for a year. Also if the tank wasn't kept full it would have accumulated a lot of water in it through condensation as diesel has no fumes to keep the air out of the tank like petrol does. Try using Millars diesel clean for a while and see what happens.

[monkeh]

The engine is hunting, when it does this have a look at the back of the exhaust, when it 'hunts' a litle puff of smoke should come out, mine does it and after treatment of the shell vpower diesel, its reduced considerably, both belts have been done on my car, so I'm certain its not them.
Apparantly it could be the injectors, mine are due for renewal but until it fails the MOT, ill think ill have to sit and wait till I have funds to get a set of recon's.
Does anyone know how much a set of reconditioned injectors cost now?

[irish940d24]

See if theirs any smoke when this happens again. If it blows whiteish black smoke on cold start and similar when warm its probably a slight timing issue seeing as the belts were replaced recently the injector pump had to be or maybe wasn't timed or not properly.

If the engine seems to shake continually on idle when warm then take off the crankcase breather hose (top of engine) and cover it with finger for few seconds on idle, if it makes pressure then its likely you've worn/Brocken piston rings. This won't be noticed as much when cold because the rings are tighter, if this Is the case then have a compression test carried out to be sure

[monkeh]

I remember sorting the hunting out, I Increased the fuelling by turning that little screw on the side in a tad, increasing the fuelling. Sorted it out.
But now that cars a coke can somewhere...

[willvg95]

Originally Posted by irish940d24

See if theirs any smoke when this happens again. If it blows whiteish black smoke on cold start and similar when warm its probably a slight timing issue seeing as the belts were replaced recently the injector pump had to be or maybe wasn't timed or not properly.

If the engine seems to shake continually on idle when warm then take off the crankcase breather hose (top of engine) and cover it with finger for few seconds on idle, if it makes pressure then its likely you've worn/Brocken piston rings. This won't be noticed as much when cold because the rings are tighter, if this Is the case then have a compression test carried out to be sure

This may or may not help but:

Smoke on diesels, if its white, its unburnt diesel, not to be mistaken by steam! If it produces white smoke when the engine is warm. This could point to low compression. Not sure if that could cause hunting or not?

Black smoke is overfuelling. The diesel is being ignited but doesnt have the capacity to fully burn within the combustion chamber.

Blue smoke is burning oil, bad rings, pistons/bores , turbo bearing, valve guides/stem seals

If its hunting, it could be that the idle is set too low. The Americans seem have a fetish for a hunting idle, they call it a "Lope" idle, infact there was a chap on the d24.com forum who purposly setup his 760gle d24 to achieve a similar affect...

https://youtu.be/XleGtdDvxRM

believe these engines are supposed to sit at 750rpm for non turbo d24s and 830rpm for turbo d24s.
I actually just dropped the idle of my 940 tdic from around 900rpm to 600rpm ish, any lower than that and my engine was hunting. It also could be as mentioned above dirty injectors. And dont run it on supermarket crappy fuel! Ha