a 2l-t knocking

[roversnomore]

hey all, i know this isn't a 24v engine and i also understand that there isn't much love for the 2l-t... that being said, this one runs well, hardly smokes on cold startup. the valve train looks really tidy and unworn. this sound really seems to be coming from the head, it resonates the heatshields on the turbo... i wonder if it's a wrist pin or something in the head... maybe even an injector that is opening early?

 

[roversnomore]

i pulled the injectors and the glow plugs, things looked ok from there. i presume that the head must come off. I moved the injectors to see if the sound moved with them, no dice.

 

[Eurasiaoverland]

I was going to suggest:

While the engine is running, slacken the nuts on the injector pipes on the top of the injectors one at a time, to identify which cylinder is making the noise. Then replace the inector of the noisy cylinder with another, and see if the noise moves with the injector. But maybe you have done this already.

From the video, it sounds like bad rod knock, but it could be other things. Check the exhaust manifold for cracks. You could also try to pinpoint the noise with a stethoscope or similar (long screwdriver to the ear etc).

Also, try putting vacuum on the timing compensator on the bottom of the pump. As I said in your previous thread, I have never seen one of these, but over-advanced timing makes a lot of diesel knock. You can also check the timing line on the injection pump flange and timing case.

 

[GTSSportCoupe]

Generally these early 2lt are pretty well regarded.

I think I've read before they can drop pre-cups (or was it valve seats?) though. At high km.

You can check big end bearings with engine in the car by dropping oil pan and removing rod caps. But really, if you spun a bearing, your oil should be very sparkly! Just change it and see.

Finally, make sure your timing belt is okay and didn't skip.

 

[roversnomore]

the engine has 170k on it. the oil looked fine . I did the timing belt and messed with the pump timing, no improvement. i double checked the pump timing and belt, it all looks good. i was worried about possible runout in the pump shaft but it is ok. i did find as per eurasiaoverland suggested that the knocking goes away when i loose the fuel injector nut on cylinder #4, i swapped the injectors around and it is still on number 4. would the engine stop knocking without fuel if is was a mechanical issue? or is the injection pump pump more likely?

 

[roversnomore]

you were correct in suggesting that i test injectors for effect on the sound.

 

[roversnomore]

I was going to suggest:

While the engine is running, slacken the nuts on the injector pipes on the top of the injectors one at a time, to identify which cylinder is making the noise. Then replace the inector of the noisy cylinder with another, and see if the noise moves with the injector. But maybe you have done this already.

From the video, it sounds like bad rod knock, but it could be other things. Check the exhaust manifold for cracks. You could also try to pinpoint the noise with a stethoscope or similar (long screwdriver to the ear etc).

Also, try putting vacuum on the timing compensator on the bottom of the pump. As I said in your previous thread, I have never seen one of these, but over-advanced timing makes a lot of diesel knock. You can also check the timing line on the injection pump flange and timing case.

this was good advice. thank you.

 

[roversnomore]

i spoke with local fuel injection place and they ruled out the fuel system and the injectors moving didn't change the cylinder with the knock. it sounds like it is internal, maybe piston slap... i guess this makes sense in a way, that the piston wouldn't slap if there wasn't ignition happening.

 

[Eurasiaoverland]

To me, that sounds too loud to be piston slap, and piston slap would go when the engine gets up to temperature.

Also, diesels have taller pistons which are far less prone to rocking in the bores compared to pistons in a petrol engine.

I think it's time to take the engine out and check the bottom end.

 

[Eurasiaoverland]

the engine has 170k on it. the oil looked fine . I did the timing belt and messed with the pump timing, no improvement. i double checked the pump timing and belt, it all looks good. i was worried about possible runout in the pump shaft but it is ok. i did find as per eurasiaoverland suggested that the knocking goes away when i loose the fuel injector nut on cylinder #4, i swapped the injectors around and it is still on number 4. would the engine stop knocking without fuel if is was a mechanical issue? or is the injection pump pump more likely?

Sorry, I missed this particular post.

Yes, the rod knock would stop when no fuel is injected as there is no explosive force driving the rod down onto the crank pin.

The diesel injection pumps on these engines are extremely well designed and very rarely cause problems.

 

[roversnomore]

To me, that sounds too loud to be piston slap, and piston slap would go when the engine gets up to temperature.

Also, diesels have taller pistons which are far less prone to rocking in the bores compared to pistons in a petrol engine.

I think it's time to take the engine out and check the bottom end.

this sound gets louder as the engine warms. it really sounds like it's coming from above the piston. I am on the lookout for a gasket set, any recommendations? but i'm back thinking it's the wrist pin... either way, i guess i need to pull apart at least some of the motor.

oh and, the valves look good from above, similar sideways (minimal) movement on all and the stem seals look good and intact.

 

[Eurasiaoverland]

this sound gets louder as the engine warms. it really sounds like it's coming from above the piston. I am on the lookout for a gasket set, any recommendations?

It'll be interesting to see what it is. Possibly a broken pree-combustion chamber, though hopefully not.

For parts I would recommend you familiarise yourself with a parts catalogue, e.g. on the Partsouq website. Not sure if you'll find a genuine gasket kit for your very early 2L-T, in which case you'll need to look for aftermarket options. Make sure you buy them for the correct engine date as the later 2L-T engines (88 onwards) have different gaskets for most parts.