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Discussion Starter · #1 ·
My beautiful 78z has the strangest noise coming from the heater core area under the glove box(it sounds just like my bike did with playing cards in the spokes!) when the following conditions are met:
1. when the temp control lever is 2/3 or more towards the hot setting
2. and when the rpm is 2500 and above(the higher the rpm, the louder and higher the frequency of the noise)
This noise is not affected by the speed of the blower as it will do it even if the blower is off. I feel it is related to another problem with the temp control itself...it will run either hot or cold, no in-between. So needless to say as soon as the valve is opened for the water to come in, the noise starts. Since it takes a contortionist to even see whats going on under there I thought I'd get some advise before I hurt myself. Any ideas...please help!! Jay
 

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Maybe your heater valve

> My beautiful 78z has the strangest noise
> coming from the heater core area under the
> glove box(it sounds just like my bike did
> with playing cards in the spokes!) when the
> following conditions are met:
> 1. when the temp control lever is 2/3 or
> more towards the hot setting
> 2. and when the rpm is 2500 and above(the
> higher the rpm, the louder and higher the
> frequency of the noise)
> This noise is not affected by the speed of
> the blower as it will do it even if the
> blower is off. I feel it is related to
> another problem with the temp control
> itself...it will run either hot or cold, no
> in-between. So needless to say as soon as
> the valve is opened for the water to come
> in, the noise starts. Since it takes a
> contortionist to even see whats going on
> under there I thought I'd get some advise
> before I hurt myself. Any ideas...please
> help!! Jay

I know that home heating systems which rely on radiators and have a hot water circulation pump can make funny noises. Maybe the same thing is going on here. If your heater valve was partially blocked or something, the water circulating through to the heater core could cavitate (air bubbles form), or otherwise make funny noise. This would explain the connection with the engine rpms and the lack of connection with the blower fan.

Just a thought.
 

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Re: pull blower !!

plull the blower moroe I had a problem of noise and low air I pulled the Blower and
found it clogged with insulation... !!!
 

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My Z makes the same noise and I found that it is the heater control valve. The valve slide is not attached to the mechanism so when the coolant flow is right it rapidly cycles from open to closed. The only fix I can see is to replace it with a new valve.
 
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