Got a message from my dad recently. He has been investigating a ticking noise in his e23 735i. He had readjusted the valves multiple times but could not eliminate or even find the noise. Here is his approach, I was impressed:
So, my hight school education is still paying me dividends…
I figured it out…
I called my work phone # and left me a message recording of my engine sound, as you know.
I get an automatic email with that message as a wav file, as you know.
I download a free audio mixer program that show me the wave form of the sounds
I expand it and I see visual ticks.
The scale on the audo display is in seconds so I count 10 ticks and see they are 1.47 seconds, ie 0.147 sec per tick.
That’s 6.8 ticks per second
408 ticks per minute. What could be running at 400 RPM, or soke whole fraction of that????
My tachometer shows close to 600 RPM.
I know a 4-cycle engine turn the cam shaft at 4:1 ratio, ie.. 150 ROM, does not match 400 ticks or any whole multiple!
Then I see somethng new on RealOEM diagrams.
There is a chain driven oil pump n the sump!
The oil pump chain is driven by the same main crank sprocket as the cam shaft ( 2 sets of teeth, same number of teeth)
But how fast is the oil pump RPM? It has a big sproket on iit.
I find pics of the main crank sproket, it has 18 teeth.
I find pics of the oil pump sproket, it has 27 teeth. So there is a 27:18 ratio, or 3:2.
So if the engine running 600 RPM, guess what!
The oil pump is running at 400 RPM!
So cool!
So, I really believe, the ticking is the oil pump!
See screen shots below…
Wave form of WAV file in attached photo
So, my hight school education is still paying me dividends…
I figured it out…
I called my work phone # and left me a message recording of my engine sound, as you know.
I get an automatic email with that message as a wav file, as you know.
I download a free audio mixer program that show me the wave form of the sounds
I expand it and I see visual ticks.
The scale on the audo display is in seconds so I count 10 ticks and see they are 1.47 seconds, ie 0.147 sec per tick.
That’s 6.8 ticks per second
408 ticks per minute. What could be running at 400 RPM, or soke whole fraction of that????
My tachometer shows close to 600 RPM.
I know a 4-cycle engine turn the cam shaft at 4:1 ratio, ie.. 150 ROM, does not match 400 ticks or any whole multiple!
Then I see somethng new on RealOEM diagrams.
There is a chain driven oil pump n the sump!
The oil pump chain is driven by the same main crank sprocket as the cam shaft ( 2 sets of teeth, same number of teeth)
But how fast is the oil pump RPM? It has a big sproket on iit.
I find pics of the main crank sproket, it has 18 teeth.
I find pics of the oil pump sproket, it has 27 teeth. So there is a 27:18 ratio, or 3:2.
So if the engine running 600 RPM, guess what!
The oil pump is running at 400 RPM!
So cool!
So, I really believe, the ticking is the oil pump!
See screen shots below…
Wave form of WAV file in attached photo
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