Engine "Woo Woo" Noise

[OsoMoore]

My distributor is back together and engine is running great (thanks wwest, timmy2, tirwin, and the rest of the PP ignition geniuses).

However there is an odd noise that has been emanating from the engine throughout the adventure, and has not dissipated along with the arcing fix. It is a hollow "woo woo woo" noise, similar to the sound of blowing across the top of a glass soda bottle. It only appears once the engine has warmed up. Sometimes it stops, but soon returns. With the engine lid closed, you cannot hear it very well unless you are listening for it.

Maybe a vacuum leak of some kind?

[wrxnofx]

Sounds like a resonance to me. See if the fan blades are rubbing on the housing.

[DRACO A5OG]

Did you re-build your dizzy?

[OsoMoore]

Originally Posted by DRACO A5OG

Did you re-build your dizzy?

I took apart everything except taking the weights and springs. Cleaned the metal parts with carb cleaner, cleaned the plastic parts with electrical contact cleaner. Killed three toothbrushes and many paper towels.
Got rid of lots of metal filings and grime. Removed a partially disintegrated bronze washer in the bottom of the housing. Replaced that giant washer with a new one. Oiled everything and reassembled it with new pins and proper shims to negate any up-down play. I was planning to replace the top bushing but there was no side-to-side play at all, so I left that for now.
I'm not sure if that qualifies as a "rebuild" since I didn't replace springs or soda blast and such. But it is all smoothly spinning and clean, no slop, and seems to be working fine.

Originally Posted by wrxnofx

Sounds like a resonance to me. See if the fan blades are rubbing on the housing.

Ok, I'll carefully inspect the inner surface of the housing. I've seen pictures of what this can lead to, and it's not cheap!

[DRACO A5OG]

Did you replace the Bronze Thrust washer with another Bronze one or metal?

[OsoMoore]

Originally Posted by DRACO A5OG

Did you replace the Bronze Thrust washer with another Bronze one or metal?

I presume you are referring to the one that rides between the top bushing in the housing and the bottom weights' disk on the rotor shaft? I replaced it with another bronze one that came with my shim kit.

It was the big one on the right:
[IMG]https://www.************.com/images/Product/medium/1196.jpg[/IMG]

[CCM911]

I had that same sound at one point, but never quite figured it out.

It was either my alternator bearings, or my engine compartment blower fan.

I had the alternator rebuilt, and I replaced the blower fan. I do not have that noise anymore.

[DRACO A5OG]

Perfect, Yes, that is the thrust washer. I think this is normal for the rebuild because if you recall and looked at the housing and below the weight assembly, it was damaged/grooved due to the disintegrated steel shims. Mine also makes a slight "woo woo" sound after recent rebuild. I will give it a month for the bronze to seat in and will re-inspect the thrust washer. If need be, I will revert back to OEM setup of Steel/Fiber/Steel shims for the upper and lower assembly.

I will also call PK to see if this is normal.

[DRACO A5OG]

I know there should be 0.10MM up/down play after rebuild.

[OsoMoore]

Originally Posted by DRACO A5OG

I know there should be 0.10MM up/down play after rebuild.

Mine was something close to that. Little enough I didn't have any reasonable way to measure it even with my micrometer. But enough that I could feel it move when I pulled.

[DRACO A5OG]

Good, I am waiting for a call back from Kurt at PK.

[DRACO A5OG]

Which one sounds like yours?

A:


B:

[OsoMoore]

Neither A or B sound like mine. Mine has a more hollow tone. What I hear in A and B is more like a bee hive.

[DRACO A5OG]

I used a stethoscope and I could not hear any discernible abnormal noise emanating from the dizzy. please check yours.

[DRACO A5OG]

Originally Posted by OsoMoore

Neither A or B sound like mine. Mine has a more hollow tone. What I hear in A and B is more like a bee hive.

Mine was O2S connected and disconnected after checking with the stethoscope. Hmmm?

[DRACO A5OG]

I used headphones to listen to your "wha wha wha" noise. I hear it more clearly now. It does sound resonate. See if you can isolate with stethoscope or remove belt and see if it can be heard without the belt.

[DRACO A5OG]

Brother Oso, I have some bad news.

Just spoke to Kurt, this is classic "record player syndrome", once the housing and weight assembly is gooved the new shims/thrust will work but the side affects is the resonant "woo woo" or "wha wha" sound.

We can leave this alone but it will soon wear out the kit we put in.

His rebuild process is to rebuild the assemblies and machine the surfaces so they will out last OEM specs with his shim set.

Okay I am done, I am sending my dizzy in for a rebuild and balance.

I think we can prove this by borrowing a known good dizzy to see if the noise goes away.

Doh! $9.89 fix, yeah right, not on these cars :-(

Jim

[OsoMoore]

Originally Posted by DRACO A5OG

Brother Oso, I have some bad news.

Just spoke to Kurt, this is classic "record player syndrome", once the housing and weight assembly is gooved the new shims/thrust will work but the side affects is the resonant "woo woo" or "wha wha" sound.

We can leave this alone but it will soon wear out the kit we put in.

His rebuild process is to rebuild the assemblies and machine the surfaces so they will out last OEM specs with his shim set.

Okay I am done, I am sending my dizzy in for a rebuild and balance.

I think we can prove this by borrowing a known good dizzy to see if the noise goes away.

Doh! $9.89 fix, yeah right, not on these cars :-(

Jim

I have a friend with an '80 SC. I'll compare with him next time we meet up. Fortunately, it is a fast swap and check - the worst part is getting to TDC.

[DRACO A5OG]

I hear yeah brother! I am going to borrow a 75K Mile dizzy from my buddy.

[OsoMoore]

Still heard it last night after putting some more miles on the new distributor washer. I'll see if I can distributor-swap this weekend.

After some more listening, I think it is actually coming from inside the fan housing. I am not sure of the best way to check the source. Maybe it is time to use a hose to do a fake stethoscope with some hose?