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TDI 200 loud knock on tickover

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Good afternoon,

 

Please tell me this isn't main bearing time?

My TDI has developed a very loud knock from the lower end of the engine. The stethoscope suggests that it's nearer the water pump, than the crankshaft. Disco timing chest, defender induction system.

This sounds goes away once above tickover, gone under power. Oil change had no effect, but the oil was done August last year, so that shouldn't be an issue.

It's a loud knock, mechanical, I've attached a .wav file, audio, but I don't know if it helps.

Help?

My recording 1.wav

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Posted (edited)

Loose water pump pulley bolts can cause something like that, so check they're tight. 

Edited by lo-fi

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Is the crank pulley bolt tight ? Also what is the damper rubber like ?

If it was main bearings the noise would be there all the time , usually worse on over-run . Big ends usually worse on acceleration . Does the oil light go out normally ?

Do you have a spare set of injectors to swap in ? and have you tried cracking one injector pipe nut at a time at the injector with it ticking over .

Is there any noticeable unevenness  when running?

cheers

Steve b

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Cracked injectors, it just ran rougher, but with the knock.Took off fan belt, no difference. A fair degree of play in the water pump, but that's for another day.

How would I test the damper? 

I might the the spare injectors done, and maybe the spare IP pump. 

Thanks, all.

I'm green laning tomorrow, the wise of the club will help, I hope.

 

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Mine knocked and it was the damper - and I could reproduce it simply by rocking / rotating it from one direction to another with the belt off ....

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I would fit an oil pressure gauge as standard, it gives you an idea of what is going on.  BTW main bearings tend to rumble rather than knock.  Crank damper is good to check.  If the oil light is not flickering on tickover then I would suggest that it is probably not big ends (not infallible though).  As a stop gap if it is only on tickover increase the tickover speed slightly until you solve the problem

Good luck

Peter

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I think the damper will be the first thing to try.

What's involved in changing that?

And can it wait until I do the timing belt, this winter?

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I'd definitely check the damper - not only for the rubber-boding delaminating but also for the tightness of the bolt that holds it to the crank.

I've seen a couple of cases where the bolt has come loose [it's supposed to be Loctited and torqued-up to something quite ridiculous] and the result was the groove in the crank-nose for the woodruff-key for the damper and the bottom timing-belt sprocket got mashed up to the point where a new crank was needed.

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Looks like the lightweight build will be postponed for a bit....

 

Thanks, I'll do some research on the damper and get shopping.

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I would go for the crank damper. My Freelander had the same problem, and I thought it was the big ends. With mine, you could see wher it was starting to wear into the timing case.

You could try putting a work lamp near it at night, and see it you can see any "fairy dust" metallic particles coming off.

Do NOT be tempted to run it for long like this, and under no circumstances try to lock the thing solid by welding, there is a high chance of snapping the crankshaft.

Bolt is very tight. I made up a tool twenty odd years ago to hold it still, which I still have.

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I'll start planning the job now.

 

Thanks.

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The knock is still there, with the damper removed. But, and this is strange, when I started the truck first, it wasn't as bad.

I'm changing the damper anyway. As I've bought the parts.

And it wasn't loose, the torque gun couldn't undo the bolt, it took the starter to unstick it.

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So, it's either injection pump/injector, timing belt/tensioner, or an engine bearing.

Joy.

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I think I might dump a load of 2 stroke oil in it, and go for a burn. 

Once the new damper had been fitted.

The old one has a fair number of cracks, so probably time to change anyway.

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IMG_20190819_200954.jpg

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Valve clearances? I've just reset them, but I'm still open to something odd Inn that area. I didn't check for the valves caps when I did it. 

The noise is loudest near the cam belt tensioner, using the stethoscope.

Could this be the cam shaft? Or a push rod doing something wrong?

Further work tomorrow. I fear.

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Les Henson posted on here once that Big end knock is noticeable when pulling away or going up a hill in a high gear. At idle or sustained revs they don't tend to do it.

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I don't think it's big end. I hope it's not the con rod bearings. 

I'd rather not overhaul the engine this month!

I'll poke around the cam and rockers a bit more.

But it's shaping up like an engine rebuild...

Ah, well, always wanted to do one!

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Big ends are conrod bearings. 😉

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Little end, then. Whatever. It means the 109 is off the road. 

 

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They can wear out, but I have been told that is uncommon.  It’s the crank bearings, including big ends, that take most of the wear.  The big end shells are easy enough to replace in situ, and I think the crank main shells would be doable without removing the crank shaft with a bit of effort sliding the upper shells around to drop them out the bottom and then sliding the new in, but you’d need to be careful not to put too much downward pressure on the crank that could damage the seals at either end ( I suspect the gear box pinion shaft will keep the crank well aligned enough to prevent rear seal damage, but be careful all the same), and you may need to slacken the two belts up front to prevent the crank being pulled upwards as the upper shells come out.

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7 minutes ago, Snagger said:

The big end shells are easy enough to replace in situ....

Not on a Defender 200TDI......

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Not as simple as an earlier 2.5 or the 300 because of the ladder frame, which needs the oil pump out of the way first, but not that bad.  The biggest snag is if the four longitudinal bolts into the rear of the ladder have been countersunk in a Series retrofit without drilling the bell housing to allow bolt extraction without separating the bell housing from the flywheel housing...

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2 minutes ago, Snagger said:

Not as simple as an earlier 2.5 or the 300 because of the ladder frame, which needs the oil pump out of the way first, but not that bad.  The biggest snag is if the four longitudinal bolts into the rear of the ladder have been countersunk in a Series retrofit without drilling the bell housing to allow bolt extraction without separating the bell housing from the flywheel housing...

There is no way to remove the ladder frame with the gearbox attached to the engine.  This is not a "snag".

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