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]

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]

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]

http://cdn.meme.am/instances/400x/43920861.jpg

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]

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

[rwdkev]

Will,

You beat me to on the subject of smoke!

white smoke = unburned fuel
black smoke = partially burned fuel
blue smoke = oil

I'd start with the basics of injector reconditioning, pump timing and idle speed. Whilst these might not cure the problem, they are worth doing regardless as they can only help the engine run better.

The fact that it is hunting when warm may also be poor quality fuel or fuel starvation caused by blocked fuel filter or underfuelling caused by incorrect pump adjustment.

If the cold start device is working, then the fact that this temporarily raises the idle speed when the engine is cold could be masking the problem. When the engine is warm, the cold start device back-off and the pump returns to its basic idle setting.

[skyship007]

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

If the previous owner didn't do the cam belt service job himself, contact the garage to get a full copy of the receipt.

First question, has the engine been serviced correctly as regards the air filter and fuel filter ??
When you replace the fuel filter it's always a good idea to fill the housing with a direct feed injection cleaner, like Liqui Moly Diesel Purge, as that will be more effective than an in tank additive. Make sure both O rings supplied with good quality (Volvo or Bosch) fuel filters are changed.

Next thing would be to GET THE HIDDEN FAULT CODES READ, cos there must be at least half a dozen potential causes of the symptoms described, including incorrect timing (One tooth out), HP pump fault, bad injectors and various sensors.

[skyship007]

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.
john

None of the diesel sold in the EU has a lubricity issue, although some of the cheap stuff does cause long term gum deposits in the injectors.
Some diesel sold in the US did have a problem with lubricity some years ago and it resulted in quite a number of damaged Bosch HP pumps, but that has been sorted now.
All EU fuel contains a percentage (Around 5) of Bio diesel and that extra is a real good pump lubricant.

I would never use anything other than a major brand fuel additive for cleaning, just in case it's not compatible with the seals.

If you think the fuel tank is dirty, do not use a Biocide or additive to clean it as all the gunk will finish up in the fuel filter and some cheaper additives are bad for the HP pump and seals. Just dump the fuel.

[monkeh]

Fault codes on a d24 760?
https://media.giphy.com/media/bB5ghmGwLbK4U/giphy.gif

But seriously, Do the 940's d24's have OBD compliance?
Ive only ever worked on 760 d24's

[willvg95]

Fault codes on a d24 760?
https://media.giphy.com/media/bB5ghmGwLbK4U/giphy.gif

But seriously, Do the 940's d24's have OBD compliance?
Ive only ever worked on 760 d24's

Doesnt the abs have a obd1 port ?
I believe you read the fault codes on a d24 with a 17mm spanner ? Ha

[RoyMacDonald]

None of the diesel sold in the EU has a lubricity issue, although some of the cheap stuff does cause long term gum deposits in the injectors.
Some diesel sold in the US did have a problem with lubricity some years ago and it resulted in quite a number of damaged Bosch HP pumps, but that has been sorted now.
All EU fuel contains a percentage (Around 5) of Bio diesel and that extra is a real good pump lubricant.

I would never use anything other than a major brand fuel additive for cleaning, just in case it's not compatible with the seals.

If you think the fuel tank is dirty, do not use a Biocide or additive to clean it as all the gunk will finish up in the fuel filter and some cheaper additives are bad for the HP pump and seals. Just dump the fuel.

UK diesel has 7% bio added to it.

[RoyMacDonald]

Fault codes on a d24 760?


But seriously, Do the 940's d24's have OBD compliance?
Ive only ever worked on 760 d24's

Not on MY1991 that's for sure. Mine was all mechanical. Never went on a computer at any of the main dealers or independents.

[frielp]

The hunting problem is the Injectors my d24 tic suffered the exact same symptoms a quick fix i tried which is still working a year later is to get a new fuel filter (MANN) fill it up with (Liqui Moly Diesel Purge) and let it run and clean the gum off the injectors or use the old school diesel mechanis trick of filling the fuel filter with mineral ATF !!

[skyship007]

The hunting problem is the Injectors my d24 tic suffered the exact same symptoms a quick fix i tried which is still working a year later is to get a new fuel filter (MANN) fill it up with (Liqui Moly Diesel Purge) and let it run and clean the gum off the injectors or use the old school diesel mechanis trick of filling the fuel filter with mineral ATF !!

Old school tricks are not a good idea in a modern common rail injection system. ATF might be a good solvent, BUT it was designed for Auto boxes or steering gear and they use very different seals to a high pressure fuel pump or injectors, so there is a long term risk of damaging the HP pump in particular.

Mann make good quality filters, BUT some Volvo diesels were designed for use with long life fuel filters made by Bosch. They have a zig zag element pattern that most copies do not. I use Mann air and oil filters, BUT stick to genuine Volvo or Bosch main dealer fuel filters.