rod knock, vanos, or normal ?

[Pklauser]

OP, please update with findings as you get them!

[Moi]

OP, please update with findings as you get them!

Will do. Thanks for all the replies

I have an appointment to do the rod bearings on Monday anyway but I'm going to get it towed to the shop tomorrow so they cna properly diagnose it

[sapote]

Agree someone experienced ought to take a look at it, but I want to speculate a bit. Could it be that as oil pressure increases it gets more oil to the bearing and lessens the knock?

I hear the knock following the increased rpm but the combustion/exhaust noise increased too and over powered the knocking noise.
Hopefully the crank is still OK.

[Moi]

so my mechanic didnt get to it yet but i found these videos online and i believe this is what it sounds like. thoughts?

https://www.youtube.com/watch?v=lu9EkG_wksE

https://www.zpost.com/forums/showthread.php?t=1437147

[sapote]

so my mechanic didnt get to it yet but i found these videos online and i believe this is what it sounds like. thoughts?

https://www.youtube.com/watch?v=lu9EkG_wksE

https://www.zpost.com/forums/showthread.php?t=1437147

It's amazing that the loose sleeve bolts sound like rod knock in those video.
At 850 rpm idling, the crank turning about 14 rev per second and the cam at 7 rev/s. I checked some rod knock video and they sound a little faster beat (the two down strokes can sound different) than loose cam bolts video.
I would simply remove the vanos hub and check the 6 sleeve bolts.
If it's loose cam bolts then you are lucky. This problem can be taken care yourself.

[Moi]

It's amazing that the loose sleeve bolts sound like rod knock in those video.
At 850 rpm idling, the crank turning about 14 rev per second and the cam at 7 rev/s. I checked some rod knock video and they sound a little faster beat (the two down strokes can sound different) than loose cam bolts video.
I would simply remove the vanos hub and check the 6 sleeve bolts.
If it's loose cam bolts then you are lucky. This problem can be taken care yourself.

crossing my fingers, thank you

[eacmen]

If you know RPM engine is running at and can isolate the sound in a sound editor should be able to compute the frequency fairly easily.

But you also should be able to easily discern if the sound is coming from top end or bottom end.

[sapote]

I wonder what makes the loose cam knocking like this? It means the cam in one revolution at some point it going down hill and then at some point it going up hill to expose the backlash/plays caused by the loose bolts. It's a 6 lobes cam (and not just one lobe which has down hill and up hill stages) and I would think the 6 lobes always going " up hill" all the time (otherwise we should hear 6x higher the knocking rate).

[OldRanger]

so my mechanic didnt get to it yet but i found these videos online and i believe this is what it sounds like. thoughts?

https://www.zpost.com/forums/showthread.php?t=1437147

Thanks for posting that link to the ZPost board. It’s worth a look for all of us running these engines. The video and commentary is a helpful bit of information on what kind of noises to take seriously. I see it this way: just because your rod bearings are recently done, that doesn’t mean you can ignore knocking. In the winter, on cold start I have a very minor knocking sound that is only perceptible listening closely from the front of the car. It goes away when warm.

I have done the solenoid from Besian, but no other VANOS work. 166K miles.

I suppose even without codes or degraded performance there comes a time VANOS maintenance is due as a preventative measure.

[tlow98]

Thanks for posting that link to the ZPost board. It’s worth a look for all of us running these engines. The video and commentary is a helpful bit of information on what kind of noises to take seriously. I see it this way: just because your rod bearings are recently done, that doesn’t mean you can ignore knocking. In the winter, on cold start I have a very minor knocking sound that is only perceptible listening closely from the front of the car. It goes away when warm.

I have done the solenoid from Besian, but no other VANOS work. 166K miles.

I suppose even without codes or degraded performance there comes a time VANOS maintenance is due as a preventative measure.

With the number of low mileage failures of hubs and cam bolts I don’t think I’d own a car without knowing, but I’m pretty risk averse so there’s that. The hub failure doesn’t give any warning or indication until it’s gone and then the timing skips and bye bye motor.

[sapote]

The hub failure doesn’t give any warning or indication until it’s gone and then the timing skips and bye bye motor.

The video link posted by OP is about the loose cam sleeve bolts which can lead to engine damage without any error codes.
If the hub bolts are loose, this should cause the cam timing codes to pop up.

[tlow98]

The video link posted by OP is about the loose cam sleeve bolts which can lead to engine damage without any error codes.
If the hub bolts are loose, this should cause the cam timing codes to pop up.

I should have specified hub tabs on the pump disc. Maybe ‘hub’ is the wrong nomenclature, but I don’t believe the pump disc tabs give warning with respect to codes?

[Slideways]

I should have specified hub tabs on the pump disc. Maybe ‘hub’ is the wrong nomenclature, but I don’t believe the pump disc tabs give warning with respect to codes?

One broken tab won't, but two broken tabs should generate a code.

[sapote]

I should have specified hub tabs on the pump disc. Maybe ‘hub’ is the wrong nomenclature, but I don’t believe the pump disc tabs give warning with respect to codes?

Broken pump disk tabs should not cause engine damage due to pistons hitting valves, unless the broken tabs got tangled between the chain and cam sprockets to cause skip chain.

[tlow98]

Broken pump disk tabs should not cause engine damage due to pistons hitting valves, unless the broken tabs got tangled between the chain and cam sprockets to cause skip chain.

True.