ZX TD Volcane -serious fault?

CoyoteBoy ( snipped-for-privacy@hotmail.com) gurgled happily, sounding much like they were saying :

Really silly question - the throttle pedal and cable are both moving freely

- and more importantly, returning to rest on the spring? The MOT man hasn't done something silly like manage to wedge a floor mat onto the loud pedal, has he?

Other than that, check the oil level, air filter and the breather circuitry

- it *might* be somehow sucking engine oil in, causing it to run - don't forget that it's the fuel that's throttle-restricted on a diseasel, not the air. Did they do anything else, like a service or any other maintenance or repair work?

Since no-load revving a diseasel to the limiter is part of the MOT, it certainly shouldn't do.

As far as we can see the throttle pedal/cable is fine, but its worth a double checking I guess - that'd be a nice cheap solution!

The car hasnt had any service work done on it recently, about 6 months ago it had filter etc but it has been sat unused for some weeks as the seat needed replacing, so maybe something got stuck with lack of use. Does the system have an ECU or is it all vacuum/mechanical control? Is a fault with the fuel pump likely to cause this sort of fault? Is the throttle on the fuel in the pump or seperate do you know?

I'm glad to hear no-load revving doesnt hurt it, id have died if my car had hit the limiter unloaded lol :)

James - a little happier

Coyoteboy ( snipped-for-privacy@hotmail.com) gurgled happily, sounding much like they were saying :

Always worth checking the stupid things...

Depends on the age of the car and the type of the pump fitted. I'm not an expert, though.

That's what the limiter's for...

"The throttle cable is fine, but the pump throttle arm felt a little tight / gritty (without cable attached)

Air filter isnt that old, but surely doesn't cause that all of a sudden, Oil level - again has used some but not massively or more than normal, Pulled fine before taking it to them eitherway without smoke!

More than a bit clackety - sounds like my valves are sat on the pistons!

Will check vacuum hoses - nothing looked out of place, although a breather hose has split but has been a little for a while with no problems. (special part taper hose)" Thanks for the thoughts so far. James

"runaway diesel" may, possibly, be the problem

here's an example of this phenomenamonon [sp] , 3/4's down the page

hth and good luck

RT

You give no details of the vehicle, what year, and how many miles? This is important. What colour smoke came out when it revved. If it is burning breather oil, due to a very worn engine, then it would be bluish white smoke. If it looked normal to sooty, then it is probably some problem with overfuelling. However, the cut off solenoid should then have stopped it. Remember that the throttle control is only on the pump, and has no effext on the air intake. Thus if the engine can find any other fuel to burn, it will run on. This includes oil in a worn engine.

brian ( snipped-for-privacy@tesco.net) gurgled happily, sounding much like they were saying :

The subject line gives a subtle hint as to the first two of those.

:D Ta Adrian lol, but i did miss some info i must admit. Its '94 i think, no more than 90K miles, in good shape, pulled well with nothing but light smoke on startup before this, light oil usage before this - no idea now as it cant be driven safely. Now it's chucking out what my brother describes as 'blue/black/grey' smoke lol when it goes nuts, and now its idling ok (if noisy, better described as a normal diesel sound but louder), but a touch on the loud pedal makes it go skyward but in a smoother less rattly way.

HTH James

runaway diesel syndrome:

And finally, a word about 'runaway diesels'. This is a nasty little problem which can affect any diesel where the crankcase breather pipe feeds direct into the air intake.

Land Rover turbodiesels are notorious for it, and I have seen it on 1.9 Peugeot/Citroen diesels as well. What happens is that on a worn engine, gases blow past the sides of the pistons and into the crankcase. They emerge from the crankcase breather laden with oil mist from the crankcase, which feeds into the air intake. Now a diesel will run quite happily on oil mist, and so the revs will increase as this extra 'fuel' is taken in. The higher revs result in greater crankcase pressure, more oil mist is forced out of the crankcase and sucked in to the engine, and a vicious circle is created.

Eventually the point is reached where the engine is generating enough oil mist that shutting off the supply of diesel by switching off the ignition will not stop it. The engine runs faster and faster, generating huge clouds of grey or black smoke, until it blows up.

If your engine starts to run away, you can sometimes stop it by selecting top gear, jamming your right foot hard on the brake and letting the clutch out to try and stall the engine. But diesels generate a lot of torque, and if the clutch is weak, it will just slip. In this case there is nothing you can do other than abandon the car, retire to a safe distance and wait for the engine to explode. Do not under any circumstances open the bonnet - it isn't worth the risk.

repeat: "The engine runs faster and faster, generating huge clouds of grey or black smoke"

the clues are there, no ?

RT

RT, yup, this possibility is under investigation as we speak (well, not quite as its chucking it down with rain) and im hoping its that simple, since this seems to be the only explanation people have im guessing its so, but the engine is a lower milage, non-smoker,non-oil consumer normally so it'll be hard to pinpoint i guess - no obvious cause if the turbo isnt shot.

My main concern was how strong the fuel pump unit was, whether a stiff/slightly gritty feeling action on the cam means it is shafted inside, or if thats pretty unlikely.

Muchos thankyou-os :)

James

Coyoteboy ( snipped-for-privacy@hotmail.com) gurgled happily, sounding much like they were saying :

90k (miles, I presume?) is nothing for a 1.9TD.

You sure it's 90k? Got history to back that up?

IIRC 90K yes, miles, and of the thousand variety :) Its certainly not a high miler (unless im mistaking it with another ZX TD i know, one is

120K, one is 90K, but either way its only a young'un, and yes, got history and is tidy/smooth enough to back it up) J

Latest information - whipped off the turbo-IC hose - properly lined with sump oil :( took off the breather that feeds from the top of the dipstick 'pot' into the intake before the turbo and nothing comes out of that when running. Fire up without the turbo hose on and a nice mist of black oil coats your face :( 99% certain its a blown turbo then.

The loud knock it gets is very strange though i must admit - seems to be a slightly random very loud deisel knock (like someone is randomly slamming the block with a hammer)- just once or twice in a second then nothing for 2-3 seconds. Doesnt vanish under load but smooths out to some extent under revs. Other than that one nasty knock noise it seems sweet so i may try to find a replacement turbo and give it a shot. Are the turbos common faults on these? we've been offered one for =A330 from a local garage. Should be a simple-ish job - easier than on my celica where it meant taking the whole front of the car off virtually. Cheers all round for those who helped. J