454 Engine Fan Noise on Class 'A'
Charlie and Ruth Hoffstatter
Class A on a Chevy Chassis with a 454 engine. Having only had diesel
pushers I am not aware of how much noise the engine on a gas job should
make. You cannot carry on a conversation with the person in the
passenger seat. I seems like the fan clutch (if it has one) might be
engaged all the time. Even at an idle after starting it up cold the fan
roars. Does this seem normal?
Any suggestions, ideas, fixes.
Charlie in Texas
BD (Dave) Thompson
"Charlie and Ruth Hoffstatter" <fol...@worldnet.att.net> wrote in message
news:3AC7CE84...@worldnet.att.net...
The fan clutch may have been replaced with an after market 'flex' fan that
is extremely noisy. The fan clutch on my '92 Class C failed and the only
thing that was really satisfactory was a factory replacement.
Additionally, check CLOSELY for air leaks around the dog house (engine
cover). If any air gets through, sound gets through also.
--
Dave
W F Sill
wrote:
>My friend is in the process of buying a very clean 1992 Allegro Bay gas
>Class A on a Chevy Chassis with a 454 engine. . . . I seems like the fan
>clutch (if it has one) might be
>engaged all the time. Even at an idle after starting it up cold the fan
>roars. Does this seem normal?
It's normal for the fan clutch to remain engaged for a short time
after startup - but not normal to stay on continually.
Will Sill KD3XR
"I don't want everyone to like me. I should think
less of myself if some people did". - Henry James
Bob Barnhart
fan. It is noisy at start-up and then stays off except when the motor gets
hot and then it comes on for only a minute or so. It is noisy when it is on,
but it should shut off. This type of fan is much more economical as the
motor runs free when cooling is not required.
"BD (Dave) Thompson" <A...@For.It> wrote in message
news:tcfgol7...@corp.supernews.com...
Jon Porter
news:3AC7CE84...@worldnet.att.net...
Fan clutch should not be fully engaged all the time. A quick test would be
to spin it by hand when the engine is cold, it should turn with some
resistance but not spin freely. Warm up the engine, shut it down and try
again. The clutch should offer a lot more resistance now since it's hot and
take some real effort to turn. Fan clutches for a Chevy typically used to
cost me about $50 or so, doing the labor myself. They can cost more.
Also, noise could be coming from leaking exhaust manifolds. Is the underside
of the doghouse lined with that noise dampening fire resistant material?
W F Sill
>Fan clutch should not be fully engaged all the time.
True. They will normally be engaged for a short time when you first
start up, but after than will be essentiually disengaged until the
engine is HOT.
>A quick test would be
>to spin it by hand when the engine is cold, it should turn with some
>resistance but not spin freely. Warm up the engine, shut it down and try
>again. The clutch should offer a lot more resistance now since it's hot and
>take some real effort to turn.
This is true ONLY if the engine is really hot - not merely warmed up
to normal operating temperature.
Dick Lucas
class A. For years I had an 83 Southwind with a 454 in it. I bought it new
and thought that there was something wrong with it because it wouldn't
upshift when it got hot. I went so far as to take it to a Chevy dealer to
find out why 4th gear wasn't engaging. What I found out was that I had a 3
speed, and the "upshift" was the fan clutch disengaging when the ram air got
the radiator cool enough. That generally occurred around 40 mph.
I now have a 97 HR Endeavor with a CAT engine. For one thing, the engine is
now 30 feet behind me, instead of under my feet. I am now able to carry on
a normal conversation at 60mph.
One thing I'd check before saying that it is normal is to check whether or
not it has electric fans. As I recall, some of the 454s went to electric
fans in the late 80s and got rid of the fan clutches. This was done for
fuel economy reasons rather than noise. If you still have a radiator fan
clutched to the engine, I'd say that the noise is normal. You might be able
to do a retrofit to electric fans, but I'd try to ride in one to see if the
noise reduction is worth the cost.
Dick Lucas
Charlie and Ruth Hoffstatter wrote in message
<3AC7CE84...@worldnet.att.net>...
Bob Barnhart
like a jet coming right under you. I have a late 80's class A and until
you're used to it you do wonder why the motor shifted to such a low gear.
"Dick Lucas" <dick_...@agilent.com> wrote in message
news:98633684...@cswreg.cos.agilent.com...
lechugon
flex fan. It will sound like a 737 reversing thrust. They are far less efficient
than the factory fan because they flatten out from centrifugal force. An
electric after market fan replacing the factory fan is inadequate and is not
efficient enough to cool a 454. Here in Arizona, you can drive around with only
an electric fan, but you aren't going to pull anything in the summer. The best
cooling for a 454 is a good radiator, with the factory fan and a factory
replacement fan clutch. Fan clutch failure is common, although not noticed as
much in cool climates. The electric auxiliary fan, in front of the radiator,
which is run thermostatically, should start at about 200-210 degrees F. if I
remember right. Further cooling can be achieved by placing second, small, after
market electric auxiliary fan in front of the radiator on the driver's side and
simply wiring it to the other fan. You need the proper thermostat also.
If you want to get olympic, you can add a single ground wire off the aux. fan to
a switch in the cab, and have the option of turning on the aux fans at lower
temperatures, or before towing up a hill. The on/off is controlled by a ground,
the aux fan being wired hot, so you only need the single wire, grounded to good
metal in the cab, or a negative post on the fuse box, through your switch.
-John