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From: genius on 28 Jun 2010 11:54
Hey All,

Need some advice again. I have a 1995 mustang gt, 5.0L, ~90k miles
that, all of a sudden, runs hot according to the in dash temp gauge.
4 years ago I replaced the ECT and all hoses, belts, coolant and
thermostat (180 degree unit). Never had a problem with overheating
and it never got to the right of the 12 o’clock position on the
gauge. After not running it for a couple months, I drove it in
ambient 75 degree weather and the gauge was on the “L” of “NORMAL”.
It wasn’t in the red but maybe a needles width or two below. It
climbs to the “L”, the fans kick on and then it drops down to the
“A”. I just replaced the temp sender to the gauge and have the same
problem. According to Haynes, the sender should read 97 ohms cold and
drop as the engine warms up. Mine read 330 so I replaced it.
Replacement read 280 ohms cold so I got yet another one that also
reads about 300 ohms cold. Is the book wrong or do I really have 3
bad sensors?

I have started it cold and held my hand on the upper radiator hose
until it got hot which was at the “M” of “NORMAL.” That hose used to
get hot at the “O” and then fans came on between “R” and “M”. I
suspect it’s the gauge itself but don’t know how to check it. I went
to my FLAPS and they had a mechanical temp gauge that went in the
radiator but it was $150+. What should my next step be here?

TIA,
Derek
From: Brent on 28 Jun 2010 12:39
On 2010-06-28, genius <genius(a)socal.rr.com> wrote:
> Hey All,
>
> Need some advice again. I have a 1995 mustang gt, 5.0L, ~90k miles
> that, all of a sudden, runs hot according to the in dash temp gauge.
> 4 years ago I replaced the ECT and all hoses, belts, coolant and
> thermostat (180 degree unit). Never had a problem with overheating
> and it never got to the right of the 12 o?clock position on the
> gauge. After not running it for a couple months, I drove it in
> ambient 75 degree weather and the gauge was on the ?L? of ?NORMAL?.
> It wasn?t in the red but maybe a needles width or two below. It
> climbs to the ?L?, the fans kick on and then it drops down to the
> ?A?. I just replaced the temp sender to the gauge and have the same
> problem. According to Haynes, the sender should read 97 ohms cold and
> drop as the engine warms up. Mine read 330 so I replaced it.
> Replacement read 280 ohms cold so I got yet another one that also
> reads about 300 ohms cold. Is the book wrong or do I really have 3
> bad sensors?

most likely the haynes manual is wrong.

> I have started it cold and held my hand on the upper radiator hose
> until it got hot which was at the ?M? of ?NORMAL.? That hose used to
> get hot at the ?O? and then fans came on between ?R? and ?M?. I
> suspect it?s the gauge itself but don?t know how to check it. I went
> to my FLAPS and they had a mechanical temp gauge that went in the
> radiator but it was $150+. What should my next step be here?

You could use one of those infrared temp measuring things.

Might want to check the thermostat. Maybe it went bad despite the low
age.

If the fan isn't coming on at the correct temp then check the fan's temp
sensor. I don't know about the '95 5.0L, but my '97 4.6 has two temp
sensors. One for the gauge the other for the fan.




From: genius on 28 Jun 2010 13:02
On Jun 28, 10:39 am, Brent <tetraethylleadREMOVET...(a)yahoo.com> wrote:
> On 2010-06-28, genius <gen...(a)socal.rr.com> wrote:
>
>
>
> > Hey All,
>
> > Need some advice again.  I have a 1995 mustang gt, 5.0L, ~90k miles
> > that, all of a sudden, runs hot according to the in dash temp gauge.
> > 4 years ago I replaced the ECT and all hoses, belts, coolant and
> > thermostat (180 degree unit).  Never had a problem with overheating
> > and it never got to the right of the 12 o?clock position on the
> > gauge.   After not running it for a couple months, I drove it in
> > ambient 75 degree weather and the gauge was on the ?L? of ?NORMAL?.
> > It wasn?t in the red but maybe a needles width or two below.  It
> > climbs to the ?L?, the fans kick on and then it drops down to the
> > ?A?.  I just replaced the temp sender to the gauge and have the same
> > problem.  According to Haynes, the sender should read 97 ohms cold and
> > drop as the engine warms up.  Mine read 330 so I replaced it.
> > Replacement read 280 ohms cold so I got yet another one that also
> > reads about 300 ohms cold.  Is the book wrong or do I really have 3
> > bad sensors?
>
> most likely the haynes manual is wrong.
>
> > I have started it cold and held my hand on the upper radiator hose
> > until it got hot which was at the ?M? of ?NORMAL.?  That hose used to
> > get hot at the ?O? and then fans came on between ?R? and ?M?.  I
> > suspect it?s the gauge itself but don?t know how to check it.  I went
> > to my FLAPS and they had a mechanical temp gauge that went in the
> > radiator but it was $150+.  What should my next step be here?
>
> You could use one of those infrared temp measuring things.
>
> Might want to check the thermostat. Maybe it went bad despite the low
> age.
>
> If the fan isn't coming on at the correct temp then check the fan's temp
> sensor. I don't know about the '95 5.0L, but my '97 4.6 has two temp
> sensors. One for the gauge the other for the fan.

Thanks for the reply. I thought about one of those infrared temp
things but where do I point it, thermostat housing? How accurate are
they? If they are within 20 or 25 degrees I would think that would
help. Yes, the 5.0L also has 2 temp sensors, the ECT for the PCM and
the sender for the gauge. Both replaced. If it was the thermostat,
wouldn't the fans come on before the thermostat opened? If that
happened I would have caught that when holding the upper hose.
From: Scott Dorsey on 28 Jun 2010 13:30
genius <genius(a)socal.rr.com> wrote:
>
>Thanks for the reply. I thought about one of those infrared temp
>things but where do I point it, thermostat housing? How accurate are
>they?

The cheapies are accurate to within a couple degrees. WAY less expensive
and more accurate than the old optical pyrometers.

One thing you can do is check various places along the radiator... the
incoming water should be hotter than the outgoing water, and there should
not be any cold spots in the radiator. If you see cold spots, it is because
some sections of the radiator are clogged.

The cooling system will work fine if the coolant is circulating properly.
A clog in the radiator, a bad thermostat, a bad water pump, or a clogged
block can keep the coolant from circulating properly.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
From: Chumley on 28 Jun 2010 17:00

"Scott Dorsey" <kludge(a)panix.com> wrote in message
news:i0am7u$3gr$1(a)panix2.panix.com...
> genius <genius(a)socal.rr.com> wrote:
>>
>>Thanks for the reply. I thought about one of those infrared temp
>>things but where do I point it, thermostat housing? How accurate are
>>they?
>
> The cheapies are accurate to within a couple degrees. WAY less expensive
> and more accurate than the old optical pyrometers.
>
> One thing you can do is check various places along the radiator... the
> incoming water should be hotter than the outgoing water, and there should
> not be any cold spots in the radiator. If you see cold spots, it is
> because
> some sections of the radiator are clogged.
>
> The cooling system will work fine if the coolant is circulating properly.
> A clog in the radiator, a bad thermostat, a bad water pump, or a clogged
> block can keep the coolant from circulating properly.
> --scott
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."

water pump vanes corrode, 1995 is probably due for replacement.

if not electric fan => the Fan Clutch could have gone bad.

Does it overheat with AC on or off ?

The radiator cap may have lost its pressure holding capability, replace.

Watch the water level closely and see if you losing steam or water over
time, if not gauge is off.

if you have a code reader, you could get the "water temp" as put to the
computer.

many after market thermostats are not that good.

Good luck and let us know what you find out

-1993 5.0 8# KB







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