'79 Thermostat

I helped my son replace the thermostat in his Mustang today, assuming
that his 'no heat' problem was typical. We bought a 'stat from Autozone
that claimed to be original equipment.

The first thing we did when we got home was drop the "bad" 'stat in a
pot of water with the good one, and fire up the stove. They both opened
up at about 190-200, but the new one opened up a lot farther.

I'm thinking that's too high...any idea what the temp of the 171ci
(2.8) 6-cyl engine is supposd to be?

-John O

"JohnO" > wrote in message
ups.com...
> I helped my son replace the thermostat in his Mustang today, assuming
> that his 'no heat' problem was typical. We bought a 'stat from Autozone
> that claimed to be original equipment.
>
> The first thing we did when we got home was drop the "bad" 'stat in a
> pot of water with the good one, and fire up the stove. They both opened
> up at about 190-200, but the new one opened up a lot farther.
>
> I'm thinking that's too high...any idea what the temp of the 171ci
> (2.8) 6-cyl engine is supposd to be?
>
> -John O
>

195

Al

Big Al wrote:
> "JohnO" > wrote in message
> ups.com...
> > I helped my son replace the thermostat in his Mustang today, assuming
> > that his 'no heat' problem was typical. We bought a 'stat from Autozone
> > that claimed to be original equipment.
> >
> > The first thing we did when we got home was drop the "bad" 'stat in a
> > pot of water with the good one, and fire up the stove. They both opened
> > up at about 190-200, but the new one opened up a lot farther.
> >
> > I'm thinking that's too high...any idea what the temp of the 171ci
> > (2.8) 6-cyl engine is supposd to be?
> >
> > -John O
> >
>
> 195
>

Thanks, Al. The son reports that the heat now works well enough.

-John O

"JohnO" > wrote:

>
> Big Al wrote:
>> "JohnO" > wrote in message
>> ups.com...
>> > I helped my son replace the thermostat in his Mustang today,
>> > assuming that his 'no heat' problem was typical. We bought a 'stat
>> > from Autozone that claimed to be original equipment.
>> >
>> > The first thing we did when we got home was drop the "bad" 'stat in
>> > a pot of water with the good one, and fire up the stove. They both
>> > opened up at about 190-200, but the new one opened up a lot
>> > farther.
>> >
>> > I'm thinking that's too high...any idea what the temp of the 171ci
>> > (2.8) 6-cyl engine is supposd to be?
>> >
>> > -John O

Judging from what you say, and what you saw and making some suppositions,
the problem wasnt the stat at all... but probably low coolant level. A
typical problem.
What you SHOULD have looked for is that it fully closed

OPENING temp of the thermostat has little to do with heater; except the
lower the stat temp, the lower the air temp from heater.

--
Yeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price
you pay..DEAL with it!

> Judging from what you say, and what you saw and making some suppositions,
> the problem wasnt the stat at all... but probably low coolant level. A
> typical problem.
> What you SHOULD have looked for is that it fully closed
>
> OPENING temp of the thermostat has little to do with heater; except the
> lower the stat temp, the lower the air temp from heater.
>

Ya know, you're probably right. Oh well. :-) Fortunately we didn't
spend a lot on this, and the kid gets some experience and a fresh load
of coolant.

-John O

"JohnO" > wrote in news:1167519651.940051.43690
@i12g2000cwa.googlegroups.com:

> They both opened
> up at about 190-200, but the new one opened up a lot farther.
>

That was the whole problem. The 2.8 thermostat does double duty by closing
off the heater bypass when fully open. Only partially open meant that the
bypass was still open.

elaich wrote:
> "JohnO" > wrote in news:1167519651.940051.43690
> @i12g2000cwa.googlegroups.com:
>
> > They both opened
> > up at about 190-200, but the new one opened up a lot farther.
> >
>
> That was the whole problem. The 2.8 thermostat does double duty by closing
> off the heater bypass when fully open. Only partially open meant that the
> bypass was still open.

Hey! All things considered, I like your answer better than BM's...but
only because it means there really was a mechanical problem and not a
maintenance problem. :-)

But either way...

-John O

Backyard Mechanic > wrote in
:

> OPENING temp of the thermostat has little to do with heater; except the
> lower the stat temp, the lower the air temp from heater.

EXCEPT on the 2.8, where the thermostat also closes off the heater bypass
when it is open.