Noise from the 930 CIS Monster engine

HAH · 07-04-2016, 12:33 PM

I have a question regarding the "creaking" noise with the Porsche 930 3.3l Turbo CIS Monster engine. The sound occurs is more common when the engine is warmed up, (gear on or idling doesn't matter). The sound is in the most simpliest frequency like one when you would throw nut into a metal can. If it's warmed more like in demostration.

Demostration video via following link: https://youtu.be/p7AgKkqvFLI

Otherwise the engine and the car works perfectly. Maybe the turbo boost is not quite like it use to be and feels like the cylinders not getting enough fuel after 1,1bar pressure.

I have checked all the air hoses, turbo air propeller axle, by-pass, wastegate, spark plugs and cables and everything seems to be ok. Also all of the visible fasteners.

You guys have any idea from where the sound might come and what could be
the issue?

I would appriciate any advce since in Finland the driving season is quite short and I still have a time to get it fixed before next garrage season

T77911S · 07-05-2016, 05:56 AM

that sounds like a relay or something other than an engine mechanical part.

nice smooth sounding engine.
were you making the RPM's change or was it doing that on its own.

again, great sounding engine.

HAH · 07-05-2016, 06:05 AM

Thanx it's even better without that "not so good noise" �� My associate was throttling the gas lever during the demo and rise the RPM's. Any other diagnosis than relay sound?

'76 911S 3.0 · '76 911S 3.0's Garage

https://www.youtube.com/watch?v=yoxnN2Nh0Lc

In this video you posted, the fan pulley looks like it wobbles a bit, especially when you give it throttle. Maybe the fan nicking the housing?

Laneco · 07-05-2016, 10:44 AM

That REALLY sounds like the fan blade just nicking the housing. With the engine off, I would look for scraped off paint/coating on the housing. When I've had them nicking - it's usually on the bottom but I did have one that contacted on the top around the 11am position.

That said...wow this car looks absolutely badass!

angela

HAH · 07-06-2016, 12:13 PM

I have checked the fan housing and unfortunately there aren't any worning of coating or paint in there.

Someone must have had similar symptoms than in my demostration video: https://youtu.be/p7AgKkqvFLI

Any other route causes?

Brian911T · Brian911T's Garage

I'm a NFG but it could be the dump valve gaskets being worn. If not get a cheap stethoscope and move it around to see if you can isolate the click sound.
If it is the dump valve this could help:
http://forums.pelicanparts.com/porsche-911-technical-forum/71370-changing-930-dump-gaskets-pictures-galore.html

HAH · 07-07-2016, 10:05 AM

That could have been the cause but not with this 930, because there is no dump valve. Only diverter valve (by-pass) which I have checked. Although the noise is similar than some dump valve videos that I found in YouTube. Thank you anyways for the quality link!

Any other hints what could be the noise source?

T77911S · 07-07-2016, 10:40 AM

does it only do it when you rev and let off the gas or will it do it at a steady RPM

Rawknees'Turbo · 11:24 AM

That sounds like a combustion leak to me. Does the engine have the original dilivar head studs? Regardless, it would be worth your time to remove the lower rocker covers and take a look.

whiz05403 · whiz05403's Garage

My fan blade has nicked the housing and that's exactly what it sounded like.

HAH · 07-08-2016, 10:01 PM

It's doing it only when rev and let of. Not in the steady RPM. The head studs should be the stronger ones. Can that kind of noise come from the broken head studs?

turbo owner · turbo owner's Garage

Look harder at the fan housing, it's a barely there sound. Loosen the fan strap a little and see if it quits or changes

Matter · 07-09-2016, 12:52 AM

check the belt on left side is not touching something when u rev. it moves at same frequency as chirp..

356911930 · 356911930's Garage

Doesn't that sound like the plastic rings in the diverter valve are shot. Each ticking noise is perfectly in sink with the throttle blip. Should pull the covers and replace the plastic rings.

Rahl

ant7 · ant7's Garage

Remove the fan belt, start the engine, and rev it a few times, [no more than about 40 sec] If the noise is gone, its fan or pulley related.
Hope this helps.

A...

WERK I · WERK I's Garage

How old is the fan belt? When they get up in years, the belt becomes hard and will actually sound like metal to metal contact. When the engine is warm as in the video, take the fan belt off and run for 30 seconds.
Other places; crank and fan pulley's, alternator bearing, blow-off valve not seated or defective(if you have one) or recirculating valve defective.

HAH · 07-15-2016, 04:40 AM

The fan housing is just painted and seems ok and the alternator belt is quite new, so I don't think that those are failing.

My plan is now following:

1. Drain the motor oil and check if any metal particles there
2. With the previous step confidence

change the BOV, drive engine warm and test 30-45s without the fan belt. If not change to noise then proceed to step 3.
3. Remove the heat exchangers and the lower exhaust valve covers to see if any damaged to head studs and cumbusion leak there?

Will update my findings to this thread.

Pls. still advice welcome what components to check?

ELZ's930 · 07-15-2016, 07:19 AM

As stated remove the belt and give it a quick test. Check the spark plug leads to make sure there is no jumping spark under initial load.

Sent from my "Driving Shoe Phone"

T77911S · 07-15-2016, 07:47 AM

Quote:

Originally Posted by 356911930

Doesn't that sound like the plastic rings in the diverter valve are shot. Each ticking noise is perfectly in sink with the throttle blip. Should pull the covers and replace the plastic rings.

Rahl

diverter valve/BOV
the DV will be open at idle due to vacuum. when you rev it the vac goes away and the valve will close then open again when you let off the gas.

its not the fan housing.