1995 mustang runs hot
genius
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
Brent
> 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
> gauge. After not running it for a couple months, I drove it in
> 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.
genius
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.
Scott Dorsey
>
>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."
Chumley
"Scott Dorsey" <klu...@panix.com> wrote in message
news:i0am7u$3gr$1...@panix2.panix.com...
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
genius
Thanks for the response. I replaced the radiator cap with a new 16lb
Stant. No coolant loss, no water in oil or oil in water. Doesn't get
any hotter or stay any cooler with ac on vs off. Car has electric
fan, it does cycle on and when idling, maybe 20-30 seconds later,
shuts down for 1-2 minutes, then repeats. I got the car hot, turned
it off and pressed my hand (where I could get it, wedged between fan
blades, belts and pulleys) against the radiator and it seemed to be
hot everywhere I touched. Crawled under the car and grabbed lower
radiator hose. It wasn't nearly as hot as the top radiator hose but
still warm to the touch. I got a stant superstat from Napa as I
thought they were supposed to be the best and coolant is nice and
green, no floaties and good to -30f according to my cheapie
hydrometer. I really suspect the gauge or sending unit but am not
sure how to test accurately. I will try to get an infrared
temperature reader as soon as I can.
thanks for the tips!
jim
genius wrote:
>
> Thanks for the response. I replaced the radiator cap with a new 16lb
> Stant. No coolant loss, no water in oil or oil in water. Doesn't get
> any hotter or stay any cooler with ac on vs off. Car has electric
> fan, it does cycle on and when idling, maybe 20-30 seconds later,
> shuts down for 1-2 minutes, then repeats. I got the car hot, turned
> it off and pressed my hand (where I could get it, wedged between fan
> blades, belts and pulleys) against the radiator and it seemed to be
> hot everywhere I touched. Crawled under the car and grabbed lower
> radiator hose. It wasn't nearly as hot as the top radiator hose but
> still warm to the touch. I got a stant superstat from Napa as I
> thought they were supposed to be the best and coolant is nice and
> green, no floaties and good to -30f according to my cheapie
> hydrometer. I really suspect the gauge or sending unit but am not
> sure how to test accurately. I will try to get an infrared
> temperature reader as soon as I can.
>
> thanks for the tips!
Are you you sure you are looking at the right sending unit for the temp
gauge. This may have one sensor for the computer and fan operation and
another that is for the temperature gauge.
-jim
hls
"genius" <gen...@socal.rr.com> wrote in message news:bdfa1f6c-d9ae-46a5-
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.
They are not super accurate... You aim them at the area you want to
measure. If you get an answer within 20F, I think that is about normal.
hls
>>
>>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.
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 normally work in the range of 160C, or that equivalent in F.
Chumley
thanks for the tips!
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Actually plain water cools the best, but in the long term causes corrosion
problems,
the green stuff is less conductive, much less corrosive, but does not have
the cooling capacity of plain water.
The thermostat should have a small hole, or small hole with small rivet in
the top half to allow steam and help open the thermostat on Mustang, well
the 93, other cars don't have it.
Fan sounds like it is doing OK, and cycling indicates it is cycling through
the temperature range, and it is sitting on the high side.
you still could have worn water pump, not sure how to check it.
I replaced mine suspecting it might be a problem when my car was running
hot, and it was corroded quite a lot, missing a lot of impeller blades,
probably only had 1/2 the amount of flow, that was at about 115k miles. I
put in a performance part. With a supercharger, you have to pull out all
the stops to get the best cooling.
http://www.scangauge.com/products/ if you can afford it, should work on a
95, tells you what the computer is seeing, so if the water temp is 200 or
so, then it is fine. The thermostat change to 180 will not lower the water
temp to 180, the engine will still produce a lot of heat. Thermostat has two
temperatures one for opening and one for closing and cycles between, the one
you have has less with the notch in it which seems fine. Stock thermostat
then water => about 220 180 => about 200 160 => about 185 or so
(approximate)
Scott Dorsey
>
>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.
dickr2
I don't know if this applies or not but ...
Back in January I gave my 1995 Ford E150 van to my son.
I had purchased the van new and put 92K miles on it with
no problems except for normal repairs (brakes, tires, etc).
My son recently took his family on a trip to Atlanta and the Gulf
Coast and, wouldn't you know, he had overheating problems.
The leaking water pump was replaced, new thermostat, and
fan, and the van still overheated.
Finally, the radiator was replaced, and no problems since then.
Is it possible that your 1995 Mustang just needs a new radiator?
FWIW
Dick in MN
hls
"dickr2" <dic...@frontier.com> wrote in message news:N2uWn.316
> Finally, the radiator was replaced, and no problems since then.
> Is it possible that your 1995 Mustang just needs a new radiator?
>
> FWIW
> Dick in MN
Good point...That is always a possibility. Some years ago it was cheap
and effective to take the radiator to a shop and have it rodded and
chemically cleaned.
Now, some of the alloys used and the construction methods may not
lend themselves to this old technology.
Really, cooling problems are usually pretty simple. There are a finite
number of things that can be happening.
And, to fix them, you have to work systematically through the system.
As in many other cases, to throw parts at this problem can be very
expensive. A little diagnosis can go a long way.
Brent
Don't forget a clogged catalyst.... that's the one that can come out of
left field.
Chumley
"Brent" <tetraethylle...@yahoo.com> wrote in message
news:i0e87a$1qd$2...@news.eternal-september.org...
How to test that one ?
my 93 is making that sound a bit now,
(had a broken one in a 89, rattled but had a loud resonance)
genius
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.
hls
Update:
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.
jim
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.
genius
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.