[V8] RE: Colder Thermostat?/Starter Saga

Stafford, Kenneth A. stafford at WPI.EDU
Wed Jul 6 11:57:02 EDT 2005


Certainly YMMV, but my V8 thermostat failed in the open position--it would
take 20 minutes of driving to get any heat during the winter.  I replaced
with a std 87 C t-stat and have been very pleased since.  My mileage went up
(maybe not in summer but certainly in winter), the cold weather surging
diminished, and the "hold-hold-hold-second-gear" habit became much less

BTW, a lot of discussion about the proper operating temps...  The '91
driver's manual clearly says not to be concerned if the temp gage goes to the
right of the center during slow, hot driving sequences.  In fact it says as
long as the overheat warning does not go on, you ought not be concerned.  A
properly operating t-stat should never limit your ultimate cooling capability
(once fully opened--say at 100C--an 87C t-stat should pass the same water as
an 80C t-stat. 

Different topic.  After replacing the starter motor and solenoid (twice), I
have defined my starting problem further.  I apparently have an intermittent
problem with the trigger signal (input to solenoid).  Tracking the wiring
diagrams, I see that this signal goes through the ignition switch then
through the transmission interlock solenoid.  Anybody have a BTDT to help me
find the most likely problem location?  The symptoms:  either starts
instantly or no engine turn at all.  When in the latter mode, you can hear
the transmission interlock clicking and a slight clicking at the starter
solenoid.  It is apparently a high impedance connection somewhere as I see 12
V at the disconnected trigger wire when the ignition switch is turned but it
drops to 8 V when attached to the solenoid.  I am currently starting the car
by an under-hood jumper from the solenoid trigger wire to the 12V post on the
passenger fender.

'91 V8Q

> My thermostat failed on my explorer last week (out in the 
> desert, pulling the trailer of course).
> It turned out that it was physically broken for a long time 
> (as evidenced by deep wear marks) and recently just siezed 
> up. I have come to realize that this motor has been running 
> on the hot side for the 15K miles that I have owned it.
> (it is at about 90K miles now) I went with a new 180F degree 
> (cold) vs the stock 195F thermostat and am seeing a pretty 
> big jump in gas mileage (from 14 to 17) when towing my 
> trailer. Now I am wondering if a colder thermostat would help the V8?
> Dave

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