Knock/noise after vanos rebuild

[Lee_Enfield]

Hello,

I just completed some winter engine work on my E46 M3. This included new rod end bearings, valve adjustment, and after finding one of my exhaust cam lobes broken, a full Vanos rebuild with the Beisan system.

Engine Things done were:
Valve adjustment
New Hub sprocket bolts
new hub spring sets
new BS Ex.Hub
BS oil disk
New BS timing chain guide
BS Seal replacement
BS rattle kit
I rebuild/re soldered the vanos solenoid myself
New Rod bearings

Timing set and checked according to the Beisan Procedure with BMW timing tools.

I fired it up for the first time the other day and it ran very smooth and quiet. However, after idling for a few minuets and it warmed up, I started to hear a tapping/knocking coming from the vanos area. It started as a sporadic knock, no rhythm, "missing a beat" to the rest of the engine if that makes sense. But began to become more constant as it continued to warm up. At this point it was getting late and shut down for the night.

Just went out and fired it up again, same thing, very quite for the first few min and once it warmed up it started to come back, same thing, sporadic at first but became more constant as it warmed up.

It is definitely coming from the vanos area. I can also feel the knock when I touch the oil accumulator line on the top of the vanos unit. I felt around other areas and cant feel anything, but it can be felt on the oil accumulator line. I don't think its a rod knock or a valve being beat by a piston as you would hear that immediately.

Any Ideas?

Thanks.

[sapote]

It is definitely coming from the vanos area. I can also feel the knock when I touch the oil accumulator line on the top of the vanos unit. I felt around other areas and cant feel anything, but it can be felt on the oil accumulator line. I don't think its a rod knock or a valve being beat by a piston as you would hear that immediately.

If no cam related codes then hopefully not valve/piston interference (minor interference may only cause the noise at different temperature). If you think it is vanos relate, then I strongly suggest to open the VC and check the oil pump disk and driving hub area.

[DoubleSidedTape]

Did you have any valves that were far out of spec? Say more than two shim sizes.

[Lee_Enfield]

Ill pop it open again when I get a chance.

For the adjustment, I didn't record what they were. I went with a go/no go meathead where if they were out I adjusted shims to where they were within limits. I remember I think about 6 or 8 valves were out. I do remember a few needed two sizes up/down though. They were fairly consistent, with the same size shims needing the same size replacement.

I am wondering, since I can only feel the tap from that oil line, could it be oil system related? something in the system that's tapping like a oil valve?

[sapote]

I am wondering, since I can only feel the tap from that oil line, could it be oil system related? something in the system that's tapping like a oil valve

A jerky turning oil pump can cause this impulse pressure shock. Check the pump disk driving tabs. You don't feel the engine rpm jerky?

[heinzboehmer]

A jerky turning oil pump can cause this impulse pressure shock.

Was going to say this.

Also OP you should check that the four pistons in the VANOS oil pump move freely (but are not too loose), if you haven't done that already. Sticky or loose pistons would cause uneven pumping and might be the cause of what you're feeling.

Edit: Oh and make sure the pump disc turns freely in the shaft on the unit itself.

[Lee_Enfield]

OK, When I pull the valve cover ill have a good look.

The Vanos looked pretty good when I put it together, I do remember the oil pump disk turning smooth.

Engine is running very smooth. Was quite happy when I first started it up before the noise started.

[cobra]

Can you get a video?

I had a grinding/knocking noise just off idle on my car. https://nam3forum.com/forums/forum/m...e-video-inside

[Lee_Enfield]

I just popped off the valve cover and removed the vanos unit and low and behold, one of the oil pistons on the pump disk was stuck. took it out and polished out the bore with some ultra fine 2k paper and it seems to be free now. Must have been a very light bur in the edge of the bore.

Just getting it back together now, hopefully that was it.

[sapote]

one of the oil pistons on the pump disk was stuck. took it out and polished out the bore with some ultra fine 2k paper and it seems to be free now. Must have been a very light bur in the edge of the bore..

Good job. This is the danger of swapping out the original pump disk with something new. I prefer to have the original disk machined with new smaller holes for the hub driving tabs, and keep everything together.

[sapote]

Quiz: so why a sticking piston causing the knocking noise like hammering?

[heinzboehmer]

Quiz: so why a sticking piston causing the knocking noise like hammering?

Irregular pumping -> fluid hammerish effect no?

[Lee_Enfield]

Well, Got it put together again and started up. Warmed up to temp, and no noise.

Thanks for all the input.

Just need to get the rest of the car together so I can drive it.