From: Scott Dorsey on
hls <hls(a)nospam.nix> wrote:
>
>Scott, I have tested these under laboratory conditions, versus mercury
>thermometers, and I have not found them to be so very accurate.. Our
>laser units are cheap, in the $100 range. Good enough for some
>types of measurements but not really good enough for what I do.
>
>Maybe within 20-25F. Maybe...

I have seen them to be better than that... but they _do_ measure surface
temperatures, so if you put a mercury thermometer into a steak and then
point an IR pyrometer at it, you should expect a sizeable difference.

>I normally work in the range of 160C, or that equivalent in F.

I was mostly interested in the things for measuring transmitting tube
plate temperatures, and I found several of them all to agree with one
another very accurately. This doesn't necessarily mean they all match
a standard reference but it's a good sign... and they did measure boiling
water within a few degrees.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
From: genius on
On Jun 28, 9:54 am, 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?
>
> 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

Update:

I took the car to a friend of mine that has an OBD1 scanner. From
what we could tell, the ECM saw the thermostat open at roughly 182
degrees. The fans kicked on at 210 degrees and off around 200. From
what we saw, everything looks fine under the hood. It looks like the
in dash gauge is the culprit which I was fearing. The parts are
extremely hard to find and expensive as can be, ~$400 via dealer which
is the only place I can even find the part.

Does anyone have any other options other than these for monitoring the
temp?
1. Ignore the gauge indefinitely (not my preferred solution)
2. Get some sort of aftermarket gauge cluster
3. Purchase my own OBD1 Scanner, keep it plugged in, tape to dash.

Thanks again.
From: hls on

"genius" <genius(a)socal.rr.com> wrote in message
news:cf6fa035-421c-4cbb-a1b2-f631283b8f9f(a)w31g2000yqb.googlegroups.com...
On Jun 28, 9:54 am, 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?
>
> 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

Update:

I took the car to a friend of mine that has an OBD1 scanner. From
what we could tell, the ECM saw the thermostat open at roughly 182
degrees. The fans kicked on at 210 degrees and off around 200. From
what we saw, everything looks fine under the hood. It looks like the
in dash gauge is the culprit which I was fearing. The parts are
extremely hard to find and expensive as can be, ~$400 via dealer which
is the only place I can even find the part.

Does anyone have any other options other than these for monitoring the
temp?
1. Ignore the gauge indefinitely (not my preferred solution)
2. Get some sort of aftermarket gauge cluster
3. Purchase my own OBD1 Scanner, keep it plugged in, tape to dash.

Thanks again.

*****

Do you have a good wrecking yard nearby? You might try that.

Second to that, I would probably get a single unit temperature gauge and
install it as professionally and inconspicuously as possible. You can get
aftermarket gauges for some cars that will fit right in the dash. I have
seen
this done, but have never done it myself.

I would be hard pressed to give a dealer $400 for something like this,
but I wont say it would never happen.

From: jim on


genius wrote:

> Update:
>
> I took the car to a friend of mine that has an OBD1 scanner. From
> what we could tell, the ECM saw the thermostat open at roughly 182
> degrees. The fans kicked on at 210 degrees and off around 200. From
> what we saw, everything looks fine under the hood.

Yes it sounded like the coolant temp sensor and fans were working as
they should. The gauge is just reading higher than it used to.


> It looks like the
> in dash gauge is the culprit which I was fearing. The parts are
> extremely hard to find and expensive as can be, ~$400 via dealer which
> is the only place I can even find the part.
>
> Does anyone have any other options other than these for monitoring the
> temp?
> 1. Ignore the gauge indefinitely (not my preferred solution)
> 2. Get some sort of aftermarket gauge cluster
> 3. Purchase my own OBD1 Scanner, keep it plugged in, tape to dash.
>

Probably the gauge is reading high because a resister that shunts some
of the current to ground is burned out or has a bad electrical;
connection. The purpose of the shunt resister (in combination with a
capacitor) is to smooth out the reading (keep the needle more steady).

you could replace the resister. It doesn't have to be under the dash.
The resistor can go from the sending unit output to ground anywhere
between the sender and gauge. If you get the right resistor it should be
as accurate as it was. A wild guess would be the resistor needs to be
around 200-1k Ohms.

The other option is to just leave it as it is. You now know what the
needle reading it is now giving mean.

-jim


> Thanks again.
From: genius on
On Jul 1, 10:41 am, "hls" <h...(a)nospam.nix> wrote:
> "genius" <gen...(a)socal.rr.com> wrote in message
>
> news:cf6fa035-421c-4cbb-a1b2-f631283b8f9f(a)w31g2000yqb.googlegroups.com...
> On Jun 28, 9:54 am, 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?
>
> > 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
>
> Update:
>
> I took the car to a friend of mine that has an OBD1 scanner.  From
> what we could tell, the ECM saw the thermostat open at roughly 182
> degrees.  The fans kicked on at 210 degrees and off around 200.  From
> what we saw, everything looks fine under the hood.  It looks like the
> in dash gauge is the culprit which I was fearing.  The parts are
> extremely hard to find and expensive as can be, ~$400 via dealer which
> is the only place I can even find the part.
>
> Does anyone have any other options other than these for monitoring the
> temp?
> 1. Ignore the gauge indefinitely (not my preferred solution)
> 2. Get some sort of aftermarket gauge cluster
> 3. Purchase my own OBD1 Scanner, keep it plugged in, tape to dash.
>
> Thanks again.
>
> *****
>
> Do you have a good wrecking yard nearby?   You might try that.
>
> Second to that, I would probably get a single unit temperature gauge and
> install it as professionally and inconspicuously as possible.    You can get
> aftermarket gauges for some cars that will fit right in the dash.  I have
> seen
> this done, but have never done it myself.
>
> I would be hard pressed to give a dealer $400 for something like this,
> but I wont say it would never happen.

I called the local wrecking yards and didn't have any luck. One of
them told me that gauge was only in the 95 mustang GT convertible and
that regular mustangs and cobras would not fit. Not sure how accurate
that is but if that is the case, finding a working unit in a bone yard
will be difficult at best. Agreed with $400 for an "indicator" but
even if I know the car is running fine, driving around with the gauge
in the red will still be disturbing.