blowjob said:

Hi i am wrighting this on be half of a friend. He has a disco on a M plate with a 300tdi engine. When the vehicle is stationary he has a knocking noise which sounds like its coming from his engine, the side where the injector’s are.any body got any clues as what it might be. Thanks

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DiscoTDi said:

Hi - what frequency is the knocking, is if for example approximately 4 knocks a second ?

If so it could be camshaft/tappet/push rod related, as you will find the noise has a frequency of around 4 knocks per second (240 knocks / min) at idle, assuming 720RPM idle (this is because each valve operates every 3rd revolution).

Identifying the frequency will allow you to narrow down the search.

Cheers

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CharlesY said:

Gosh, each valve operates every THIRD revolution!

I thought these were FOUR stroke engines, but clearly I am wrong because

Mr DiscoTDi makes it clear these are SIX stroke cycle engines ....

Let me see .... suck .... squeeze ... bang .... blow ... and another two.

Beats me.

CharlesY

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ratty said:

front or rear of the engine? Get a long handled screwsriver and use it as a stethescope to listen to each of the cylinders. You should be able to narrow sown where the knocking is coming from.

Hold each of the injector pipes with your fingers too. Are any of the pipes pulsing in time with the knock?

Is it a knock or more of a loud tick? If it's a tick, check out the brake vacuum pump.

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iannotts said:

Sure I have just seen this somewhere else

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ratty said:

I thought it was ......suck.....squeeze....bang....blow.....drink tea.....smoke fag?

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CharlesY said:

By the way, PISTON SLAP can make noises that happen only at tickover speed and off-load.

There's a cure. Four new pistons.

Alternatively, live with it if that is what the noise is.

CharlesY

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ratty said:

I am inclined to agree with you CharlesY

I drove my previous landy (300 tdi) from Scotlandshire to Bath with no problems even though I had a small end bearing gone. I then carried on driving for a further 4 or 5 months while I sourced a replacement engine. Apart from smoking for the first couple of mins when cold and the constant slap on tickover and low revs I had no issues with it whatsoever.

I even sold the fecked engine for more than I paid for the good un.

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CharlesY said:

So it was YOU who sold my mate that duff engine ...... !

CharlesY

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blowjob said:

i was told by ratty to Hold each of the injector pipes with your fingers too. Are any of the pipes pulsing in time with the knock?

he has tried this and it is pulsing very strongly with from one injector (the second one in from the front of the engine as you look at it from the front), and slightly with the 1st injector. any help guys

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