T

Toad

Active Member
Can anyone point me in the right direction. I have just done a 510 mile trip in my Discovery 300 Tdi (1994) and it ran absolutely brilliant. However I have developed a problem with white smoke coming from the exhaust. This happens at that inbetween stage of accelerating and decelerating, when you just try and hold it at a constant speed between the two. And also after I have decelerated and press the pedal to then accelerate I get a ploom of smoke momentarily.

I have checked both the water and oil and both are fine and there are no signs of white gungy stuff inside the filler caps of either of them if you are thinking it may be cylinder head gasket. There was no sign of overheating either. The car as I said ran beautifully and there has been no loss of acceleration at all, but it is a little worrying to look in your rear view mirror now and again and not be able to see anything behind you.

I will say that for most of the trip it was not a problem as long as I was accelerating or decelerating fully it was just the trying to maintain speed and accelerating after travelling down hill that caused the problem.

I'd be grateful to hear from anyone with any ideas, but be gentle as I am no mechanic.
 
Toad said:
Can anyone point me in the right direction. I have just done a 510 mile trip in my Discovery 300 Tdi (1994) and it ran absolutely brilliant. However I have developed a problem with white smoke coming from the exhaust. This happens at that inbetween stage of accelerating and decelerating, when you just try and hold it at a constant speed between the two. And also after I have decelerated and press the pedal to then accelerate I get a ploom of smoke momentarily.

I have checked both the water and oil and both are fine and there are no signs of white gungy stuff inside the filler caps of either of them if you are thinking it may be cylinder head gasket. There was no sign of overheating either. The car as I said ran beautifully and there has been no loss of acceleration at all, but it is a little worrying to look in your rear view mirror now and again and not be able to see anything behind you.

I will say that for most of the trip it was not a problem as long as I was accelerating or decelerating fully it was just the trying to maintain speed and accelerating after travelling down hill that caused the problem.

I'd be grateful to hear from anyone with any ideas, but be gentle as I am no mechanic.
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From what you say I'd reckon it's BLUE smoke and it's oil. If you've got a lot of it most likely it's a broken piston ring, but it could also be a valve seal. Trouble is that if it IS a ring it can scratch the bore and bugger your block.
The reason you see it when you do is that the oil tends to build up on the overrun and burn off (blue smoke) when you accelerate. Listen out for any odd engine noises. You won't necessarily notice much change on the dipstick at first.
I ran a car for a whole year like this with no problem. However it would probably fail MoT nowadays plus you don't know how bad the problem is.

If it definitely is white then it's coolant, and means a head gasket or, worse, a cracked head
 
Thanks for the reply Pastmaster. Is it really all bad news? You mention MOT, well funny enough it only passed one 4 days ago. Is there not a possibility that there is a problem with the fuel feed (too much maybe) and what I'm seeing is the surplus burning off. Just an idea, but I don't know what I'm talking about really. I suppose I'm just clutching at straws hoping there may be an easy solution to this and obviously a reasonably priced one.

Toad
 
Toad said:
Thanks for the reply Pastmaster. Is it really all bad news? You mention MOT, well funny enough it only passed one 4 days ago. Is there not a possibility that there is a problem with the fuel feed (too much maybe) and what I'm seeing is the surplus burning off. Just an idea, but I don't know what I'm talking about really. I suppose I'm just clutching at straws hoping there may be an easy solution to this and obviously a reasonably priced one.

Toad
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You may wnat to clean your wastegate

Take it off and get a high preassure line to clean it and put it back on

This happen to mine and it worked

Eithet that you have put a bad batch of fuel !!
 
Thanks for the reply wanagetmuddy.

Sorry to be a pain, but waste gate, where will I find that? Also when you say high pressure line, do you mean air or water.

Toad
 
Toad said:
Thanks for the reply wanagetmuddy.

Sorry to be a pain, but waste gate, where will I find that? Also when you say high pressure line, do you mean air or water.

Toad
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The wastegate is a cylinderical do-hickey attached to the turbo. You know where the turbo is, right?

If not, as you look into the engine bay, it will be on the RHS of the engine, towards the back and it will have a flexible pipe going to it from the air filter box.
 
thebiglad thanks for replying.

This cylinder on the turbo comes off easy enough does it? Is it screwed on or clipped maybe. And once off is it high pressure air or water I'll need to clean it?

Cheers Toad.
 
Toad said:
Thanks for the reply Pastmaster. Is it really all bad news? You mention MOT, well funny enough it only passed one 4 days ago. Is there not a possibility that there is a problem with the fuel feed (too much maybe) and what I'm seeing is the surplus burning off. Just an idea, but I don't know what I'm talking about really. I suppose I'm just clutching at straws hoping there may be an easy solution to this and obviously a reasonably priced one.

Toad
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No it's not all bad news. I think what I'm saying is it COULD be serious and you need to show it to a mechanic you trust (which probably doesn't mean a L-R dealer).

I doubt if it's fuel - excess fuel burns black, except when the engine is very cold first thing.

Certainly try the wastegate thing - my experience is a bit antediluvian and I don't know much about turbos (I just hope it goes on working. So far they all have).
 
Toad said:
thebiglad thanks for replying.

This cylinder on the turbo comes off easy enough does it? Is it screwed on or clipped maybe. And once off is it high pressure air or water I'll need to clean it?

Cheers Toad.
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High pressure air just give a good blasting

Afterwards I squirted wd40 for good measure

and it cleared itself up.

This happen to me when I tried bio diesel and it smoked like if it was about to blow up !!!
 
Thanks for the info. Things have now gone a step further. When I start it from cold it is now missing and the smoke just belches out of it until it warms up slightly, enough for me to be able to move off.

I have blanked the EGR valve in the hope that it may have had something to do with the problem and once warm and driving along it seems to have reduced the problem slightly, but by no means completely.

Is the wastegate on the turbo likely to cause the car to miss on start up? Was yours missing at all?

Sadly it looks like the diagnosis Pastmaster gave me at the beginning of this thread is starting to look the most likely.
 
re black smoke well your getting the same problems that i was having tried all the same as you but still had black smoke got so bad that i had to stop driving had so many people advise me as to what the cause might be and it was the turbo so i had it re-conditioned now no problems at all hope this helps
 
Toad said:
Thanks for the info. Things have now gone a step further. When I start it from cold it is now missing and the smoke just belches out of it until it warms up slightly, enough for me to be able to move off.

I have blanked the EGR valve in the hope that it may have had something to do with the problem and once warm and driving along it seems to have reduced the problem slightly, but by no means completely.

Is the wastegate on the turbo likely to cause the car to miss on start up? Was yours missing at all?

Sadly it looks like the diagnosis Pastmaster gave me at the beginning of this thread is starting to look the most likely.
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I hope You dont get what happen to me

Whilst the white smoke was belting out I had a knocking efect happening as well.

It happen all at once.

Bear in mind my car is regularly service i.e 6 oil changes last year and no I dont to exessive mileage.

Anyway when everyone thought what it was it wasnt but it was....

The cam had worked itself loose and the shim just disappered and so the car was knocking its arse off.

The noise came from the snorkel if you put the your ear to it it sounded like it was farting ...

Anyway whilst that got sorted out the smoke continued until to smoke but once I cleaned the wastegate it stopped.
 
Thanks Gary

The turbo is obviously on my list to check, but mine is blowing white smoke and not black and also it is missing on what I think is one cylinder especially on start up.

I have had someone also suggest that I may have a faulty injector. Has anyone got any thoughts on that?
 
Wanagetmuddy

I agree that the cam belt maybe at fault. This concerns me a lot as it was apparently changed only 5000 miles ago, I just wonder whether the job was done properly
 
Toad said:
Thanks Gary

The turbo is obviously on my list to check, but mine is blowing white smoke and not black and also it is missing on what I think is one cylinder especially on start up.

I have had someone also suggest that I may have a faulty injector. Has anyone got any thoughts on that?
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If the smoke is blue ish I would say yes it could be the turbo
 
Toad said:
Thanks Gary

The turbo is obviously on my list to check, but mine is blowing white smoke and not black and also it is missing on what I think is one cylinder especially on start up.

I have had someone also suggest that I may have a faulty injector. Has anyone got any thoughts on that?
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engine low on compression blows white smoke because it can't burn it properly, try slackening off each injector pipe one at a time to see which cylinder is missing. Don't think injector would cause the smoke normally if faulty it pushes out black, but worth checking. I guess you could pull the injector out and replace it with another from a breakers yard or just swap it about to see if the miss-fire moves with it.

If the missfire stays on that cylinder then compression problems could be the fault. Check your valve clearances perhaps one has run off or one is too tight. No tappety noises from the top off the engine??
 
Thanks for the ideas David.

The one of swapping a fresh injector around is an easy one as I have another 300Tdi with 4 good ones in it to do it with. When I slacken an injector off what should I expect to see or hear? I am really no mechanic and all this is very new to me.

As far as the tappets/Valves are concerned I'm not sure about the tapping noises as I can't distinguish between what are normal diesel noises and anything else.
 
Toad said:
Thanks for the ideas David.

The one of swapping a fresh injector around is an easy one as I have another 300Tdi with 4 good ones in it to do it with. When I slacken an injector off what should I expect to see or hear? I am really no mechanic and all this is very new to me.

As far as the tappets/Valves are concerned I'm not sure about the tapping noises as I can't distinguish between what are normal diesel noises and anything else.
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When you slacken the nut on the pipe at the injector it releases the presure and the injector wont fire fuel into the cylinder, sometimes you need to pull the pipe back from the injector to break the seal and you might see some fuel squirt out but it's ok and it wont go on fire.

When you do this it shuts down the cylinder and it's a very audible sound, what you are looking for is to find the cylinder that is missfiring, when you slacken off all of the good ones you will have the the good cylinder cut out and the missfire from the bad cylinder together, when you cut the missing one out you should be able to determine the difference. I hope, if you have a good ear. Remember do one at a time, when you try the first one you will see what I mean.

When you find the missing one try an injector first since you have spares.

The tapperts are in the rocker cover where you pour the oil, there should be very little noise from there, but what I would be listening for is a light tapping noise very metalic perhaps a single tap tap tap out of character from the other noises. This would be a rocker which could have either went out of adjustment or run off.

Take off the cover and what you will see are the rocker shaft and valves with adjustment nut and a screwdriver head slot on them these are what you adjust. There are two per cylinder and they are in line with the injector, so when you find the missing cylinder these are the two to look at. If you need to adjust them or one, then you really need to do them all and it's easy. If that's the fault then let me know and I'll explain how to do it.

This would mean that one of the valves would not open properly and thus low compression on that cyl, but do your checks first on the missfire.
 
Thanks for a great detailed reply David. I will go and have a look now seeing as we have more daylight this evening. Will let you know my findings.
 
Ok David. I just started the car and it was instantly ropey on tickover. However, as long as I don't touch the throttle it soon settles down to a nice tickover. Infact it settles down faster than I could get round to undoing the injectors.

Anyway I slackened them off one by one and sure enough diesel squirted out of them and each one in turn made the engine labour. I assume this means that the injectors are working.

What I will say is that when I start the car and press the throttle it behaves just like a petrol car would if it were flooded. It coughs and splutters and creates lots of white smoke that in this case smells of diesel. If I press the throttle harder it seems to get past the coughing and spluttering stage and I can rev it hard and the smoke disappears. The moment I throttle back it smokes a bit then returns to ticking over beautifully.

I have also had a listen out for any unusual ticking/tapping and there is none that I can hear, it just ticks over lovely. As I say if it were a petrol vehicle I would know instantly when I pressed the throttle that it was flooding.

I have to ask, is there a possibility of fuel starvation in my case or indeed the opposite, flooding maybe? Having said that the problem is that the car smokes even when warm so I don't know I'm probably barking up the wrong tree.
 
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