300TDi knock noise

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7th March 2020, 11:25 AM
shack

Quote:

Originally Posted by roverrescue

From OP initial post

“ Cracking the injector pipes one at a time doesn't seem to change the noise to any noticeable degree...”

Keep thinking

S

Thanks....speed read gets me again!
7th March 2020, 02:58 PM
Finnius

Quote:

Originally Posted by roverrescue

The only thing I can think of is a chunk out of a cam lobe
So with tappet adjusted there is follower pressure on the lobe but then when it rotates around there is a step or jump.

BUT

To get to that your at stripped down engine level diagnosis.

Can I commend you on your chase - you must be fully frustrated and needing a beer or seven !

Thinking back to the video it could be a single cam lobe issue - timing at idle seems about right. How bad would it be to run with the rocker cover off- probably messy but you might see some shimmy or kick at the offending tappet??? Would at least confirm noise is between cam and pushrod????

Steve

Thanks!

This morning before i start hard wiring my winch in-cab controls the hunt for the noise continued.
I pulled all the glow plugs and all pushrods and had the engine cranking over whilst i firmly held a pushrod down onto each follower with my finger.
I was hoping if there was a chunk/step in a cam lobe i would feel it without stripping the engine. But all follower actions seemed silky smooth - up and down with no notch... This was only at fast cranking speed though - i'm sure small problems sound louder when the engine is actually running.

Anyway, with all the rocker gear and pushrods removed the engine was a lot quieter when cranking to hear any noises and i can still hear a knock but it is very faint. Now keep in mind that this may be a totally different knock that is there all the time but i just don't notice it!
So i modified a stethoscope and found the faint knock to be loudest on the top of the injector pump! [bighmmm] Which is right next to where the original noise originates from.
I then pulled the timing belt off and the noise stopped when cranking - so this particular knock is not in the bottom end

I did some googling and cant see anyone who has had a knock coming from a 300TDi injector pump - only ticking noises etc when low on fuel etc....
Can the 300TDi injector pump knock?
8th March 2020, 12:57 PM
Finnius

At TDC are all valves meant to be fully closed (all pushrods fully down) which allows easier fitment of rocker shaft?

During refitting of the rocker shaft (with engine at TDC) it seesaws as number 4 valve pushrod is slightly up (more than the others)...
8th March 2020, 04:29 PM
roverrescue

TDC all valves closed

If 4 is not
Cam timing must be out a scooch

S
8th March 2020, 04:34 PM
Young Angus

Wait a minute...is that 300Tdi GREEN???? That looks awesome!!

Oh, sounds like a 300tdi to me :)

Quote:

Originally Posted by Finnius

Absolutely! They rattle so much it's hard to know if i am hearing a problem or not. I have listened everywhere with a screwdriver and the 'clack/knock' is the loudest at the front right side of the head..

I have heard the same knock my engine has, from other 300Tdi engines as well...

Here is a video of mine:

https://youtu.be/JP_43zMf7OQ

Does that louder higher pitched knock/rattle that occurs 3 or 4 times a second sound like a problem to you guys? My 300tdi engine have always rattled away but this knock noise sounds louder and slower than usual? As if it is only occurring on one cylinder perhaps. Cracking the injector pipes one at a time doesn't seem to change the noise to any noticeable degree...

If it was a big end bearing would the oil pressure definitely be low? Because my oil pressure seems to be ok. I'm not sure if my gauge is calibrated right but i get 40ish PSI isdling and 60ish PSI max.
8th March 2020, 05:48 PM
roverrescue

It’s been like three years since I stripped a TDI
But from deep within my gin soaked Nuerons
I remember having the thought once that the cam gear drive plate was a potential location for slip leading to mis timing

Ie your cam gears might line up but the lobes are off somehow.

I did have a cupboard full of parts including a cam/ gear and drive plate .... but alas no longer to remind me of the setup

S
8th March 2020, 06:18 PM
Finnius

Quote:

Originally Posted by roverrescue

TDC all valves closed

If 4 is not
Cam timing must be out a scooch

S

Ok. Yep with the camshaft notch lined up with the mark on the casing, all the pushrods are the same height except the number 4 which is a few millimetres higher than all the others. I noticed it when refitting the rocker shaft as it seesawed back and forth on it...

How exactly would the cam timing being wrong make the combustion knock/clack sound that i can hear?
8th March 2020, 06:53 PM
Finnius

Quote:

Originally Posted by roverrescue

It’s been like three years since I stripped a TDI
But from deep within my gin soaked Nuerons
I remember having the thought once that the cam gear drive plate was a potential location for slip leading to mis timing

Ie your cam gears might line up but the lobes are off somehow.

I did have a cupboard full of parts including a cam/ gear and drive plate .... but alas no longer to remind me of the setup

S

This is my rockers at TDC (marks lined up on camshaft pulley). The 4th rocker (highlighted) already starts opening the valve before the cam gets to TDC)?? I presumed that was normal as by rotating the camshaft i cant seem to ever find a position where all the valves are closed?

https://i.imgur.com/OFn92BY.jpg
9th March 2020, 07:46 AM
Tins

Quote:

Originally Posted by Finnius

Absolutely! They rattle so much it's hard to know if i am hearing a problem or not. I have listened everywhere with a screwdriver and the 'clack/knock' is the loudest at the front right side of the head..

I have heard the same knock my engine has, from other 300Tdi engines as well...

Here is a video of mine:

https://youtu.be/JP_43zMf7OQ

Does that louder higher pitched knock/rattle that occurs 3 or 4 times a second sound like a problem to you guys? My 300tdi engine have always rattled away but this knock noise sounds louder and slower than usual? As if it is only occurring on one cylinder perhaps. Cracking the injector pipes one at a time doesn't seem to change the noise to any noticeable degree...

If it was a big end bearing would the oil pressure definitely be low? Because my oil pressure seems to be ok. I'm not sure if my gauge is calibrated right but i get 40ish PSI isdling and 60ish PSI max.

If it’s a big end it won’t be long before you find out, but the oil pressure suggests otherwise. A knocking big end is usually terminal and oil pressure will fall noticeably.

Check the VP. The noise can refer up the camshaft.
9th March 2020, 09:28 AM
rick130

Quote:

Originally Posted by johntins

If it’s a big end it won’t be long before you find out, but the oil pressure suggests otherwise. A knocking big end is usually terminal and oil pressure will fall noticeably.

Check the VP. The noise can refer up the camshaft.

Other than the oil pressure collapsing at idle, I found big end noise only really noticeable on the overrun at high revs in aTdi?

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