Noise from the 930 CIS Monster engine

[ant7]

My theory behind the removing of the fan belt, and trying it without it was; to rule out the pulley on alternator being loose on the key!
A...

[HAH]

Hello Guys!

Today I checked two first items from the test plan without finding a route cause :/
It seems now that the noise occurs even when the engine is cold. Always on step to rev. Feels like metal click now. I listened with the antenna the timing chain housings and the lower rocker housings and can't hear the noise source.

1. Drain the motor oil and check if any metal particles there /Done
-->Oil was in excellent shape with no debris in it.

2. With the previous step confidence change the BOV, drive engine warm and test 30-45s without the fan belt. If no change to noise then proceed to step 3. /Done
--> BOV changed to a new factory model tunable OTR and fan belt removed with full alternator & belt test with no result. The noise is same than before.

3. Remove the heat exchangers and the lower exhaust valve covers to see if any damaged to head studs and cumbusion leak there?

So #3 still ahead... I have to admid that I guess that the cruising season is over for me and my 930

Still minor breath of hope in the air... if some of you guys could make the miracle happen and resolve the noise issue with the engine?

[HAH]

The demostration video link: https://youtu.be/p7AgKkqvFLI

[T77911S]

i don't think it is anything to worry about.
it sounds mechanical but not internal engine related if that is what you are worried about.
problem is with the mods on that engine you probably have something on there that we don't know you have that could be doing it.

when I say mechanical I mean like the BOV opening and closing, a solenoid switching, a relay, although pretty loud for a relay but you get my point.

you don't say what year or if you are USA. (based on the video sounds like you may be euro??)

[cmcfaul]

Sounds to me like the advance on the distributor. Every time you goose it it clicks. that corespondents to to the when the distributor would be advancing. if its not on tight or right it can hit. Easy enough to check or replace the cap and rotor.

Chris

[tharbert]

Something fall down next to the crank pulley?

[356911930]

Have you replaced the gaskets under the two silver covers on the BOV? See picture below.






Rahl

[HAH]

The issue still under investigation. Currently I suspect that that there is still something wrong with the power distribution.

Couple of days ago I installed a new spark plugs and cabling and opened the MSD Box. Found rmp resistor unattached form the bottom of the box and yelded it back. Unfortunately all of these fixes and the noise still occurs :/ I tried to localize the source with a stethoscope by listening all surfaces of the motor, but it's too hard to find out where it comes. Feels that the sound comes from the direction of first cylinder but somehow on the top of the motor.

One thing that I noticed was that if set the timing so that the idle is lagging like -8 degs and 4000rpm value +27 degs then the noise almost disapears? If we set it back to +1deg idle and +35deg 4000rpm the noise comes almost at the every throthling. I guess this not very good compromise for the optimal running of the motor. How you would set the idle and 4000rpm advance timing?

Do you guys have any ideas what could be the issue and are you able to what to do next?

I would also like to test and rule out with optional components: Power distibutor, coil and MSD box. Do you have any idea from where we could borrow those for the test or buy 2nd hand?

Items checked so far:

- BOV replaced and vacuum system checked
- Tested the fan pulley alternator without belt
- Motor Oil drained and checked for metal pieces
- Waste gate tested
- Sparkplugs and cabling replaced
- Power distributor opened and seals fixed
- Power distributor cap and rotor replaced
- Timing advance adjusted +1deg idle & 35deg at 4000rpm (vacuum attached)
- MSD box opened, checked and rpm resistor fixed

[T77911S]

35 degrees is too much.
set it to 27

[HAH]

I think that the power distributor is giving too high angle and wide range for ingnition advance. Right now it's between 950 rpm to 4000rpm from +1deg to +35deg. If I adjust it to range -8deg to +27deg the noise disapears, but this not very good for the optimal running of the motor

Could there be some worn out parts in the distributor unit?

[vintagecarlover]

What intercooler is that? I'm no help but vote removing fan belt check before spending any $ or wasting time.