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Listen to the heater valve with your stethoscope. The rubber support on mine's getting stiff,
and I can hear it cycling when I'm sitting at a light. If I turn off the heat (fan to 0) then
it stops, and if I change temperature, I can get the duty cycle to change (rate and rhythm of thump).

To find your heater valve, start at www.realoem.com and look up the diagrams. Then lift the hood
and see if you can find it, down below and in front of the brake booster. It's kinda hard to see
at first, but if you follow the coolant hoses, there it'll be.

fwiw.

t
 

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1999 323i
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Discussion Starter #22 (Edited)
Update:
I got my scrubs on and stated playing doctor!

Started on the top half of the engine and it seems most prominent when I put the stethoscope on the intake manifold (????) Put it on the DISA valve just for fun, and it wasn't nearly as prominent, but still a little audible from the stethoscope. The head is where it's the quietest. Haven't checked to see if the bottom half of the engine picks up on the stethoscope yet since I only have about 5 to 7 minutes before it gets too warm.

Next up: Belt test and bottom end Will edit this post with findings when it cools down. (Thankfully I don't work tomorrow, so I can stay up a little later with the car)

Previously unanswered questions:
  • The sound goes away after the engine starts getting warm
  • Oil level is good. A bit dirty.
Codes:

  • p0150: o2 sensor (Bank 2, Sensor 1)
  • p1189: Fuel Control (Bank 2, Sensor 1)
  • p1188: Fuel Control (Bank 1, Sensor 1)
  • DSC light is on

P.S:
Sorry for the nibbles of info at a time. This week has been an absolutely busy one and I have 101 things to do before I can even gaze at my car. I'll be trying the CCV test mentioned earlier as well as the belt and bottom end stetho.
 

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1999 323i
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Discussion Starter #27
Sapote
OP, haven't removed the belt to test yet?
Still makes the noise without the accessory belt. Looks like ICV and CCV is next on the list to check.

So the noise is coming from the engine - front or back?
And what about the oil?
Definitely coming from the top front/middle of the engine as far as I can tell.
Oil level is fine, a little dirty though. Can't get new fluids until I get paid unfortunately

Get front of car in the air and poke around underneath also.
I can now confirm with 100% certainty that it isn't coming from the bottom (Thankfully)
 

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Sorry I missed the update post. Does the low oil light eventually go out?
You say it starts to overheat after 5 minutes? Whats the coolant level doing? Thats not good.
Does the fan not kick in?
Can you make another video?
I can't see how the ICV would make a big noise. You should be able yo push your stethoscope in to it.
 

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1999 323i
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Discussion Starter #29
Sorry I missed the update post. Does the low oil light eventually go out?
You say it starts to overheat after 5 minutes? Whats the coolant level doing? Thats not good.
Does the fan not kick in?
Can you make another video?
I can't see how the ICV would make a big noise. You should be able yo push your stethoscope in to it.
Oil light is just the orange oil light which leads me to believe oil level sensor. Planned on replacing during oil change.

It doesn't overheat. The noise just goes away after the engine heats up.

Correct me if I'm wrong, but the only thing under or around the intake manifold that could possibly make that sound would be DISA valve, but it doesn't sound like typical DISA failure... not to mention it seems a hair louder.

Maybe it IS a knock, and the previous owner was just running garbage fuel?
Planned on registering, insuring, tune up, oil change, and fill-up today
 

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but the only thing under or around the intake manifold that could possibly make that sound would be DISA valve, but it doesn't sound like typical DISA failure..
you could disconnect the DISA connector to disable it, but I don't think it's the problem as it's not active at idling or low rpm.

I think CCV or ICV
 

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What if the Disa flap is loose? But then why would that go away as car warms up.
I would still like an under hood video with no narration.
 

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Could it be the clutch fan? Unplug the clutch fan and see if those goes away.


Sent from my iPhone using Tapatalk
Normally, the clutch fan would refer to the "mechanical" fan in front of the water pump. I'm not sure how one would unplug that.
OP seems to have disappeared.
 
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