Big end knock

109inches · Mar 2, 2016

i have a 200tdi in my series attached to a series gearbox.

Under load in 3rd and 4th gear there is a knocky noise, quite loud coming from the back on the engine, front of the gearbox area. However I can Rev the engine up to 3/4 throttle and hold it there for a few seconds and it's beautifully quiet just have to raise my voice slightly to have a normal conversion and it's very smooth.

So is a big end knock only noticeable under load or would it be noticeable with the gearbox in neutral and in gear?
The series gearbox is quite tired. When you get to higher revs the knock settles down.
Any thoughts?

lynall · Mar 2, 2016

Its well worth running 85/140 in the box/diffs, Im sure I read somewhere sometime ago l/r recommended this oil for severe duty and in my eyes doubling the power it has to handle is severe duty.
My S2 tdi has been fine for 5 years now, only downer is gears can be notchy when below zero for first few hundred yards.

chris7 · Mar 2, 2016

Worn big end bearings rattle and clatter with engine running
Not under load
tends to disappear when under load...
Main bearing wear produces a ...
Heavy thumping

jamesmartin · Mar 2, 2016

109inches said:
i have a 200tdi in my series attached to a series gearbox.

Under load in 3rd and 4th gear there is a knocky noise, quite loud coming from the back on the engine, front of the gearbox area. However I can Rev the engine up to 3/4 throttle and hold it there for a few seconds and it's beautifully quiet just have to raise my voice slightly to have a normal conversion and it's very smooth.

So is a big end knock only noticeable under load or would it be noticeable with the gearbox in neutral and in gear?
The series gearbox is quite tired. When you get to higher revs the knock settles down.
Any thoughts?

quite possibly its just the diesel knock echoing in the bell housing id think if increasing revs cures it, wa an issue in the 90s lr bought out an improved clutch plate to cure it

chris7 · Mar 2, 2016

To check where noise is coming from use a large...
Screwdriver or piece of wood as a....
Stethoscope

109inches · Mar 2, 2016

Thanks James I was thinking that it was just lack of soundproofing in the series and with the series clutch.

Chris the noise is from the back of the engine, bell housing area. But it's only there whilst driving in 3rd and 4th so can't really use a screwdriver or piece of wood.

I towed 2 tonnes with it up a hill high revs 2nd gear and no knocking.
But normal cruising between say 35mph and 45mph in 4th it's there increase the revs and the noise speeds up a little then quietens down completely.

lynall · Mar 5, 2016

I assume as you can do 35 in top you are on the std 4.7 diffs?

flat · Mar 5, 2016

It's probably where someone crashed into you.

Big end knock

109inches

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lynall

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chris7

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jamesmartin

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chris7

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109inches

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lynall

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flat

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