Woo Woo" Mystery Solved

D

dave lowry

New member
Jul 7, 1998
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I think I've solved the mystery of the "woo woo" sound from the engine bay
while driving. I suspected the fan clutch, so we took off the engine cover
and started it up.

The fan spun immediately. Not really a roar, but obviously pulling lots of
air. We waited for it to disengage. After about 10 minutes, with the engine
nearly up to normal operating temp, the clutch had not disengaged. I
couldn't remember anyone complaining about their clutch not disengaging,
just that they wouldn't engage when the engine got hot. As I pondered the
effects of a constantly engaged fan clutch (cool running, but lousy gas
mileage), I noticed a subtle change in fan speed, without a change in RPM.
Further study revealed that even though the engine was only turning at
about 700 RPM, the fan clutch was partially disengaging, and then engaging
about every 10 seconds - hence "woo woo" while underway at higher RPM.

It'll get a new Hayden 2797 next week, but thought I'd better report my
findings and ask if this is a common failure mode. Has anyone had a similar
failure?

We'll be looking for a little better mileage on our upcoming 4,000 mile
trip. At current prices, any improvement would be welcomed.

Dave (advisor/navigator) & Dege (ALL else), '76 Royale, Santa Barbara, CA
 
>In a message dated 06/03/2000 4:53:31 PM Central Daylight Time,

>
> It'll get a new Hayden 2797 next week, but thought I'd better report my
> findings and ask if this is a common failure mode. Has anyone had a similar
> failure?
> >>
>If you would really like to be through with your fan clutch problems for a
>long time, I'd suggest you get a GM clutch. The GM clutches have given me
>many miles of trouble free service. The Haydens I tried didn't last very
>long. GM cost more but is worth it in my opinion.

Thanks Ted. I'll keep that in mind for when I get really frustrated. For
now though, I think I'll take advantage of the fact it was a 2747 that
failed. The new 2797 will only cost me the difference to upgrade.

Dave (advisor/navigator) & Dege (ALL else), '76 Royale, Santa Barbara, CA
 
I noticed a similar "woo woo" on my maiden voyage last week. I have several
other projects to work on (I am taking this weekend off from the GMC) but will
be checking the "woo woo" next weekend. This seems like a good place to
start. Still have to work on the "thud thud", the "rattle rattle" and the
"woosh woosh".

Ron

> I think I've solved the mystery of the "woo woo" sound from the engine bay
> while driving. I suspected the fan clutch, so we took off the engine cover
> and started it up.
>
> The fan spun immediately. Not really a roar, but obviously pulling lots of
> air. We waited for it to disengage. After about 10 minutes, with the engine
> nearly up to normal operating temp, the clutch had not disengaged. I
> couldn't remember anyone complaining about their clutch not disengaging,
> just that they wouldn't engage when the engine got hot. As I pondered the
> effects of a constantly engaged fan clutch (cool running, but lousy gas
> mileage), I noticed a subtle change in fan speed, without a change in RPM.
> Further study revealed that even though the engine was only turning at
> about 700 RPM, the fan clutch was partially disengaging, and then engaging
> about every 10 seconds - hence "woo woo" while underway at higher RPM.
>
> It'll get a new Hayden 2797 next week, but thought I'd better report my
> findings and ask if this is a common failure mode. Has anyone had a similar
> failure?
>
> We'll be looking for a little better mileage on our upcoming 4,000 mile
> trip. At current prices, any improvement would be welcomed.
>
> Dave (advisor/navigator) & Dege (ALL else), '76 Royale, Santa Barbara, CA
 
Ron,
I just got rid of "click click" (OEM Hubcaps). I now have to get rid of "clunk
clunk" (broken shock?) and "rattle rattle" (bad engine A/C compressor clutch?).
It seems like just as soon as I get rid of one noise another one or two come to
the surface to take its place.

"Woo woo" is probably the next one to surface because I think I have a defective
fan clutch. However, I'm planning on a preemptive strike against that sound by
replacing the clutch before it has a chance to be heard.

By the way, is your brother ready to receive and store your new (used) steel
wheels and tires? I sort of forget about them until I cut the grass yesterday and
saw the wheels in my utility trailer.

Richard Waters
'76 PB, Troy, MI

> I noticed a similar "woo woo" on my maiden voyage last week. I have several
> other projects to work on (I am taking this weekend off from the GMC) but will
> be checking the "woo woo" next weekend. This seems like a good place to
> start. Still have to work on the "thud thud", the "rattle rattle" and the
> "woosh woosh".
>
> Ron
>

>
> > I think I've solved the mystery of the "woo woo" sound from the engine bay
> > while driving. I suspected the fan clutch, so we took off the engine cover
> > and started it up.
> >
> > The fan spun immediately. Not really a roar, but obviously pulling lots of
> > air. We waited for it to disengage. After about 10 minutes, with the engine
> > nearly up to normal operating temp, the clutch had not disengaged. I
> > couldn't remember anyone complaining about their clutch not disengaging,
> > just that they wouldn't engage when the engine got hot. As I pondered the
> > effects of a constantly engaged fan clutch (cool running, but lousy gas
> > mileage), I noticed a subtle change in fan speed, without a change in RPM.
> > Further study revealed that even though the engine was only turning at
> > about 700 RPM, the fan clutch was partially disengaging, and then engaging
> > about every 10 seconds - hence "woo woo" while underway at higher RPM.
> >
> > It'll get a new Hayden 2797 next week, but thought I'd better report my
> > findings and ask if this is a common failure mode. Has anyone had a similar
> > failure?
> >
> > We'll be looking for a little better mileage on our upcoming 4,000 mile
> > trip. At current prices, any improvement would be welcomed.
> >
> > Dave (advisor/navigator) & Dege (ALL else), '76 Royale, Santa Barbara, CA
 
Ron,

I can live with the "woosh woosh" and the "rattle rattle", it's the "squeak
squeak" that drives me nuts!

Enjoy your weekend!

Peter
77 Eleganza II
Colorado

- ----- Original Message -----
From: "RONALD KAZI"
To:
Sent: Sunday, June 04, 2000 8:22 AM
Subject: Re: GMC: "Woo Woo" Mystery Solved

> I noticed a similar "woo woo" on my maiden voyage last week. I have
several
> other projects to work on (I am taking this weekend off from the GMC) but
will
> be checking the "woo woo" next weekend. This seems like a good place to
> start. Still have to work on the "thud thud", the "rattle rattle" and the
> "woosh woosh".
>
> Ron
>

>
> > I think I've solved the mystery of the "woo woo" sound from the engine
bay
> > while driving. I suspected the fan clutch, so we took off the engine
cover
> > and started it up.
> >
> > The fan spun immediately. Not really a roar, but obviously pulling lots
of
> > air. We waited for it to disengage. After about 10 minutes, with the
engine
> > nearly up to normal operating temp, the clutch had not disengaged. I
> > couldn't remember anyone complaining about their clutch not disengaging,
> > just that they wouldn't engage when the engine got hot. As I pondered
the
> > effects of a constantly engaged fan clutch (cool running, but lousy gas
> > mileage), I noticed a subtle change in fan speed, without a change in
RPM.
> > Further study revealed that even though the engine was only turning at
> > about 700 RPM, the fan clutch was partially disengaging, and then
engaging
> > about every 10 seconds - hence "woo woo" while underway at higher RPM.
> >
> > It'll get a new Hayden 2797 next week, but thought I'd better report my
> > findings and ask if this is a common failure mode. Has anyone had a
similar
> > failure?
> >
> > We'll be looking for a little better mileage on our upcoming 4,000 mile
> > trip. At current prices, any improvement would be welcomed.
> >
> > Dave (advisor/navigator) & Dege (ALL else), '76 Royale, Santa Barbara,
CA
>
>
 
> Ron,
>
> I can live with the "woosh woosh" and the "rattle rattle", it's the "squeak
> squeak" that drives me nuts!
>

Peter,
It was the "rattle rattle" and "squeak squeak" of the OEM hubcaps that drove me
nuts. The rest of the sounds I can sort of tolerate. The hubcap sounds always
prevented me from making stealthy arrivals at the homes of friends,
campgrounds, grocery stores etc. I really hated that! Now $1800 later I can
arrive silently for the most part.

Richard Waters
'76 PB, Troy, MI
 
A little duct tape inside the wheel covers could have saved you $1800.

Just joking; I'm saving up for Alcoas myself.

Don Ogden
 
> A little duct tape inside the wheel covers could have saved you $1800.
>
> Just joking; I'm saving up for Alcoas myself.
>
> Don Ogden

Don,
I tried duct tape and it really did make a difference. I never got all
the "click click" noises out, but the tape helped. Last year I gave up
completely on tape and bending the tabs because I decided to save up for
the Alcoa's.
Richard
 
Arch,

Thanks for the ideas on the squeaks. I had all my overhead cabinets out,
tightened the nut-serts, and re-installed the cabinets with shorter bolts. I
think I'm down to one major squeak, from the inside rear view mirror area. I
think it started when I removed the ugly rubber spacers the PO had installed
under the mirror bracket...
BTW, your coach looks great! I just checked out your "Home Stretch" Album
again, nice work.

Thanks again,

Peter
77 Eleganza II
Colorado

- ----- Original Message -----
From:
To:
Sent: Sunday, June 04, 2000 10:47 PM
Subject: Re: GMC: "Woo Woo" Mystery Solved

> In a message dated 06/04/2000 10:25:24 AM Central Daylight Time,

>
> > I can live with the "woosh woosh" and the "rattle rattle", it's the
"squeak
> > squeak" that drives me nuts!
> >
> Peter
>
> May I offer some ideas? When I drove my lady home from the junk yard
> I could not believe all the rattles and squeaks. First I secured all the
> cabinets
> to the frame of the motorhome. You will find that all of the overhead
cabinets
> are not tight to the frame. I think GM made the bolts to long so that the
> workers
> did not break the wood frames. I did break one of mine after adding 2
washers.
> My closet module was held in by one corner floor brace and one drywall
screw
> shot up into the frame at the top of the door. My reefer module was held
in
> by one corner floor brace and nothing else. Both of the top braces were
not
> hooked to anything. To get rid of my squeaks I have screwed down all of
> the corner braces. Attached everything to what ever it looked like it
should
> be attached to. Then where an overhead cabinet met one of the modules I
> shot in some silicone and screwed them together. So far seems to work.
> Not what you should do just what I did.
>
> Take Care
> Arch
>
 
Richard,

I have the stainless steel hubcaps, they don't seem to squeak. I also have a
real nice set of original hubcaps, but haven't had them on the coach yet. At
slow speeds, with the cockpit slider open, I can hear the "woosh" from the
Centramatic balancers. They do a great job though, so they're allowed to
make a little noise!
Alcoas are about 4-5 years away, since I just bought 4 new tires.

Thanks,

Peter
77 Eleganza II
Colorado

- ----- Original Message -----
From: "Richard Waters"
To:
Sent: Sunday, June 04, 2000 9:35 AM
Subject: Re: GMC: "Woo Woo" Mystery Solved

>
> > Ron,
> >
> > I can live with the "woosh woosh" and the "rattle rattle", it's the
"squeak
> > squeak" that drives me nuts!
> >
>
> Peter,
> It was the "rattle rattle" and "squeak squeak" of the OEM hubcaps that
drove me
> nuts. The rest of the sounds I can sort of tolerate. The hubcap sounds
always
> prevented me from making stealthy arrivals at the homes of friends,
> campgrounds, grocery stores etc. I really hated that! Now $1800 later I
can
> arrive silently for the most part.
>
> Richard Waters
> '76 PB, Troy, MI
>
>
 
Make sure that I am standing in the woods when you throw them. A couple of mine
are looking like they have been run over by a couple of semis. Until the next
lottery ticket comes through, I will settle for Richard Waters radial rims and
E rated tires.

Ron and Julie

> The thing to do with noisy hubcaps is to carefully take them off and then
> whip them into the woods. They're nothing but fake show anyway. I'm gonna
> wait till next year to get alcoas, but in the meantime I'm going al-natural.
> Mark A
 
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