RE: IML: 73 coolant circulation

[Ken Lang <imperialken@xxxxxxxxx>]

I would also suggest that coolant is in fact circulating thru the heater
core causing the heater hoses to be hot.  The plenum door is probably closed
due to a perceived warm condition caused by a faulty sensor.  If the ambient
outside temp sensor or the in-car temp sensor are shorted it will cause the
system to run maximum cold.  Also, if the control dial potentiometer is open
it will have the same affect.

Ken
67 Crown 4 Dr Ht
68 LeBaron 4 Dr Ht


-----Original Message-----
From: mailing-list-owner@xxxxxxxxxxxxxxxx
[mailto:mailing-list-owner@xxxxxxxxxxxxxxxx] On Behalf Of Kenyon Wills
Sent: Saturday, March 31, 2007 6:24 PM
To: mailing-list@xxxxxxxxxxxxxxxx
Subject: Re: IML: 73 coolant circulation 

-- jhplc@xxxxxxxxxxx wrote:

> Hi listers.. 
> 
> Soon after the ATC quit being able to change the
> temp in the car( it is stuck on cool)  and change
> fan speeds..(unless switching from Lo to HI auto).. 
> There is no coolant going to and from in the heater
> hoses...they get really hot and there is no coolant
> in them,but the engine does not overheat because.. 
> The thermostat is new 
> The water pump is new
> The coolant is new 
> The ATC servo does not leak
> 
> This is puzzling because the temp gauge shows normal
> operating temperatures ....any ideas
> 


It is unclear to me what the question is.

This is what I would say is happening based on your
description:

ATC II Servo failed, likely due to exposure to exhaust
manifold heat or age/fatigue.

Failure was not on the exterior, but was on the
interior, letting coolant weep into the space above
the passages - the mechanism that switches the flow or
whatever, which is now corroded solid and
non-operational.

The water in both of the lines is not flowing because
the valve is in the OFF position, but the water in the
lines is touching the water in the block, and thus is
getting thermal transfer via conduction.  I predict
that the water in the hoses heats up AFTER the water
in the block heats up, but that it's difficult to
discern the rate at which each heats up.  They both
get hot after awhile.

The engine not overheating has no connection to the
ATC II.  You can bypass the ATC II or loop the hose
connection back into the block with no downside.

If you are asking if these conditions indicate a fried
ATCII unit, the answer is yes.  If you like having
control over the heat in the car, you'd do well to get
the aluminum replacement servo unit.  See the site for
that... 

The car will operate normally without an ATC II unit
or a broken one so long as there is no leak.  

A failed unit is an indication that the plastic is
weak and I encourage you to bypass the unit that you
have until such time as you get a metal replacement to
avoid a sudden loss of coolant that you fail to detect
on the road that could be followed by an engine
failure due to heat, signal sentry or no.  You are a
hose clamp away from avoiding a breakdown.

I have bypassed all three servos on the ATC II cars
that I own.  It's nice enough here in Northern
California that the windows regulate temperature well
enough to allow me to ignore the irritation of the ATC
II repair until I'm done with absolutely everything
else.

 

Kenyon Wills
 
 























 
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