Heavy smoker - 940 TD 2.4:

[echohead68]

Have a 940 turbo diesel 6 cyl 2.4. Has developed severe white smoking under a cold start (so bad it floods the whole street). Smoke clears in motion and reappears at idle. Also has an erratic idle, ie one or more cylinders are not combusting. At first I thought dirty injectors etc, not so simple. I gave it to a local garage earlier this week and got a report today. Engine and injector timing are spot on. Possibly a pump problem or a leak within the head gasket between two cylinders causing compression issue and dumping unburnt diesel into the exhaust hence the smoke and engine vibration due to misfire at idle. As I say symptoms disappear at speed. Although they cannot pinpoint this as the cause and I could anticipate a min £400 bill and yet not have cured the problem. Vehicle is M reg, late 04 registration. Help, any ideas?

[chadmat]

When was the diesel filter last changed?
Might just need a new filter, try that first.
Fill the filter with diesel injector cleaner, this will help.:thumbs_up:
Good luck!

[echohead68]

Thanks Chadmat, filter was changed 10k ago, so is due. Fill the new filter with injector cleaner? sounds harsh, what brand would you recommend? there are so many on the market. I read an article recently in the USA where a guy used auto trans fluid neat in the new filter! Could this solve smoke and erratic idle issues, not convinced...

[jor]

There are a couple of threads on the forums about 940 TD's and smoke of various hues.
The manual lists for white smoke; defective glow plugs, low compression, defective injectors or delayed injection, water leak, defective cold start device.
Under rough idle it goes on to add: injection pump sucking air via fuel line or shaft seal, fuel filter lines blocked or containing water. inlet or exhaust leakage, incorrect valve clearance (pre 93 cars).
Some list!
Presumably if there was a head gasket leak the coolant level would drop. As the engine starts ok it's not the glow plugs or poor compression.
Certainly worth asking the garage just what they did - if they have checked the injectors for spray pattern could they not have done a compression test while the injectors were out? What do they do these days to check for a head gasket, look in the expansion tank for bubbles or stick a probe in to look for hydrocarbon?
As you say changing the fuel filter is easy, as is cleaning the injectors by filling the new filter with ATF (non synthetic) but the chances of a cure are slim!
Checking the fuel lines, including the little ones that run between the injectors is something you can do yourself.
If the cold start device is working properly there should be a 200 rpm difference between cold and warm idle (1030/830).
Have a look at craig8661's posts, he had a pump seal problem and could see air in the clear fuel line from the pump. Presumably this is a fuel supply / timing problem that the garage hasn't worked out.


john

Interested to hear how you get on

[echohead68]

Thanks very much for the information John, I will certainly pass this on to the garage as they were pretty stumped and any guesswork could prove expensive. Will search for the other threads re diesel problems and give the garage as much info as I can. Thanks again, will let you know how we get on, cheets, Andy.

[craig8661]

just to add it was the shaft seal on my pump that had failed what was happening when you stoped the engine it allowed to fuel to run back to the tank and hence the air on startup as jor says make sure the fuel lines on top of the injectors is in good cond dont go on looks ither take one of and inspect to see if the rubber is brittle or cracking my volvo is dead at the min engine is fine just the slave cylinder on the clutch has failed it

[echohead68]

Thanks Craig. The pump is one of the parts the mechanic, or engineer to be politically correct, thought may be the problem. I'll have him check the seals, injector fuel lines, he should have done this already hopefully. If not so simple the pump may need to be sent away to be checked.

[craig8661]

well i kno a place in northern ireland he charges £30 to replace shaft seal place it on the bench and run it with meters and test equip to make sure its right if the shaft bearing has gone like it did on mine it would cost £60 but i had brought a second hand one and had a new seal and test to make sure it was ok allso make sure your desial filter is ok some one had lost the center o ring out of mine that caused probs too all mine needs doing now is the heater plugs may be the clutch and the clutch slave cylinder

[chadmat]

Any good quality injector cleaner will do.
I used to have that done on me diesel Transit van.:thumbs_up:
It doesn't do it any harm.
It will smoke a bit, but you're running on neat cleaner, and it will give those injectors a right good clean!!

[RoyMacDonald]

If the head is cracked or the head gasket has failed you still may not see a drop in the coolant level, but you may see an increase or dried coolant residue around the plastic coolant expansion tank.

If it is water getting into the combustion it may be that you can only see it in the exhaust when the engine is turning over slowly and it clears when the engine runs faster.

Roy

[tonyvolvo]

HI . THERE A ADJUSTER ON THE TOP OF THE THROTTLE SYSTEM. AS THE ENGINE WARMS UP IT WILL GO. IT IS LIKE AN OLD GARDENER ENGINE!!!!!!!.
MY
940 DID IT. I TAKE MY DIESELs TO A COMPANY IN BRISTOL CALLED D T M
BEEN GOING FOR A COUPLE OF YEARS.
TONYVOLVO

[echohead68]

The 940 spat out its camshaft a few days later on the A14, the AA took us home and the dealer who sold it to us,after some wrangling, agreed to take it back and refund our money, so I guess we'll never know the true cause of the original problems. However, bought an 850CD 2.5 20v today, beautiful car full spec, needs a few minor jobs doing but hopefully she'll give us more milage than the 940 diesel. Thanks for all your input guys.

[craig8661]

the volvo 940 with the d24tic engine is renowned for the cam going the vw lts was the main terminal use of there engine was the cam letting go usaly snaps halfway

[jaydbass]

the volvo 940 with the d24tic engine is renowned for the cam going the vw lts was the main terminal use of there engine was the cam letting go usaly snaps halfway

Are there any warning signs beforehand?

[craig8661]

not sure i soppose you may hear a rumble or the engine feal ruff the lt when that one snaped just cut out no warning at all
apperently its a cast cam and its prone for hairline fractures and its the fracture that fails if it suddenly goes ruff look under the rocker cover first make sure its not breaking up

[RoyMacDonald]

the volvo 940 with the d24tic engine is renowned for the cam going the vw lts was the main terminal use of there engine was the cam letting go usaly snaps halfway

That's a new one on me Craig. Where did you here that? I can't find any info to confim on the net. (Or is it a biodiesl issue?) I know the engine is known to crack the head occasionally but whether from the design or user/service dept malpractice I don't know. Mine cracked but due to main dealer malpractice. It is the weak spot of diesels in they do need care when changing the coolant and when warming up from cold.

Roy

[Derick]

I had a 740 2.4 td with a similar problem. Smoked like a steam lorry when cold, and had very lumpy idle, but ran fine on the road and didn't smoke too much when warm. A reconditioned pump completely cured all the above.

Also had a pin hole in the fuel line once - didn't run worth a monkey's at any speed in that instance.

A stupid boy with an Sprinter delivery van wrote said motor off by running head on into me. A nasty experience but legs still attached to body afterwards - went straight out and bought another volvo!!

[craig8661]

lt engine origanly they was prone even ones we went to steal parts of had bad cams
it was a coman falior even one lt we changed the engine on the cam had snapped at the pully on the front of the engine could be a nottinghamshire thing tho

[RoyMacDonald]

Maybe it's a lack of proper lubrication/service by some service place up there, as it's the top end that always suffers most from neglect.

I heard a diesel tuning specialist say that engine was strong enough to cope with 400 bhp which is a lot more than the engine is capable of putting out. The guys at the diesel place I go to really reckoned that engine. They were always trying to get me to let them bump the power up on mine but I preferred the economy tune and 0 to 60 in 11 seconds was fast enough for me and from 50 to 90 there was very little that could stay with a 940 TD. Of course "eat my dust" was not just a saying when you put your foot hard down!! Though it was the fastest diesel car ever built in it's day.

Roy