2.25 Diesel knock and wont turn off

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steveosgood

New Member
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13
Hi All,

Ive just picked up a s3 1978 2.25 diesel, and have a couple of problems that some of you might be able to help me with....

It runs fine on start up, and tickover is fine, however, when its warms up, after around 5 minutes of driving a loud knocking noise comes from the engine, and is related to the rpm, if the clutch is depressed during this period the engine will stall. if you stop long enough for the engine to cool down again the engine is fine.

the other problem is that the engine doesnt stop when you take the key out, which isnt a problem in itself, but i guess it might be related

my first thought was diesel knocking, as its reluctance to stop might indicate that, but wouldnt the banging knocking noises from the engine be happening all the time, rather than only when warm?
 
The engine stopping when you press the clutch down suggests a VERY VERY serious problem. If you have just bought the Landy, they probably sold it BECAUSE of this problem.

It may well be the the CRANKSHAFT THRUST WASHERS have collapsed or dropped out after spinning after seizing up from want of lube. Whatever, you must see to it or you WILL wreck both the crankshaft and the cylinder block. The whole description you have given points to this diagnosis.

If you bought it from a dealer - take it back.
If you bought it privately, then Caveat emptor applies, "let the buyer beware", and you have been conned by a baddie.

You can sometimes test for this diagnosis.

Working from the FRONT of the engine, use a big lever and shove the crankshaft pulley straight BACK into the engine as far as it will go. If it moves more than about 0.010" say ten thou, you do have a thrust washer problem. Anyway, with the crankshaft levered right back, get someone to press the clutch down slowly while you keep an eye on the crankshaft pulley. If you see the pulley move forwards AT ALL more than ten thou at WORST .... you can be sure the thrust washers are goosed, and possibly the crankshaft, and possibly the block.

It's an engine out job, and remove the crankshaft. Only then will it be possible to assess the damage.

CharlesY
 
thanks for the reply, im not too bothered as i picked it up quite cheap assuming the worst,

thanks for giving me something to work with!
 
As for the engine not stopping, there should be a stop cable, removing the key should have no effect, although if the cable is correctly set up, it should be impossible to remove the key until the stop cable is pulled.
 
Well that's OK, but just for fun, check the CRANKSHAFT END FLOAT anyway, and let us all know what you find. It may not be that!

But it certainly sounds like it so far.

You buy a decent 2.5NA engine for less than it might cost to fix the 2.25.

CharlesY
 
steveosgood said:
Hi All,

Ive just picked up a s3 1978 2.25 diesel, and have a couple of problems that some of you might be able to help me with....

It runs fine on start up, and tickover is fine, however, when its warms up, after around 5 minutes of driving a loud knocking noise comes from the engine, and is related to the rpm, if the clutch is depressed during this period the engine will stall. if you stop long enough for the engine to cool down again the engine is fine.

the other problem is that the engine doesnt stop when you take the key out, which isnt a problem in itself, but i guess it might be related

my first thought was diesel knocking, as its reluctance to stop might indicate that, but wouldnt the banging knocking noises from the engine be happening all the time, rather than only when warm?
Click to expand...

I would have thought if the thrust washers had dropped out then it would knock all the time, but I dont know if they can on that engine anyway sometimes they are part of the main bearings. Old triumph 2000/2500 engine had that problem and the crank would push forward when you pressed the clutch, making gear selection difficult.

Are you saying on idle the engine stalls, or as you drive along the road it starts knocking and when you declutch it cuts out.

Any smoke, or anything else to help, blip the throttle does it knock, losing water, might be a cracked piston, or as charlie says the bearings but I still think it would affect it hot or cold.
 
The knocking couyld also be an injector with a dodgy spray pattern, with the enginee running at a fast tickover , slacken off the fuel feed nut at each injector in turn, if its coming from the faulty injector it should quieten

if its not stopping, try moving the stop lever control arm on the injector pump by hand if stops then cable needs setting up as davec
 
steve2286w said:
The knocking couyld also be an injector with a dodgy spray pattern, with the enginee running at a fast tickover , slacken off the fuel feed nut at each injector in turn, if its coming from the faulty injector it should quieten

if its not stopping, try moving the stop lever control arm on the injector pump by hand if stops then cable needs setting up as davec
Click to expand...

Sure to all that but ... what about the engine stopping when he de-clutches?

I still think he MUST check for crankshaft end float VERY SOON.

CharlesY
 
The whole thrust FORWARDS of the clutch release bearing onto the clutch-cover in the flywheel is taken on the crankshaft thrust bearing, a pair of flat shells usually situated either side of the centre main bearing.

Sitting with your foot holding the clutch pedal down exposes these bearing shells to extreme stresses, and if the lube fails even for a few seconds the bearing shells can dry up, stick to the crankshaft, and spin. Then one or both can drop off the crankshaft into the sump. Caramba! No crankshaft thrust bearings.

Then the whole crankshaft tries to move forwards by the thickness of the shell, possibly as much as 4 to 5mm or even more. Catastrophic engine damage is guaranteed if this happens and you keep on driving.

CharlesY
 
Apologies for reviving an old thread but I have the same problem, but only the knocking problem.

I have only recently had the Landy back from being repaired and there have since been no problems, until now!

It went in with a bad knocking problem and the crankshaft was found to be the problem item. I have driven it today and the problem has come back. Last time when it happened I was in traffic and was slowly crawling along. Yesterday, I was in traffic and the same problem has occurred. It knocks as soon as the engine starts and idles, I cant hear it when I am driving along!

As the problem was fixed only about 4 weeks ago, could this be a re-occurrence and what causes the crankshaft to become so noisy?

Thanks in advance,
BBP
 
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