Has any one had any trouble with an erratic temerature gauge in their Areostars? In my 94 it recently has been running high on the temp gauge, over on the A in NORMAL and wavering a little. The problem has came about slowly. It had always run between the N & O. It has a new Modine radiator, new water pump(these replaced because of age and leaks), new Motorcraft thermostat, fan clutch, new Motorcraft temp gauge sending unit. I'm beginning to doubt the gauge itself. It appears the oil pressure gauge which is above the temp gauge is starting to run higher than it normally does also. Do these instrument clusters use that voltage reducer, like the older Ford trucks usd to run? I'm about ready to hook up a manual gauge to see if its really running hot. I know it not over into the "hot" range. But when you see your temp gauge running half way over the gauge, and it hasen't ever been there in the 6 years you've owned it, its upsetting! Thanks.

Superdave

94 Ford Aerostar XL 3.0L
82 Ford F250 4x4 XLT,400 CID,C-6 A/T,8700lb GVWR. Black & Silver

 

I've never had the problem, but here's a thought. You said you replaced the temp sender. What kind of sealant (if any) did you use on the sender threads? The reason I ask is because the sender is grounded to the engine through the threads of the sender. So, if you used something like teflon tape or anything that is non-conductive, that may be your problem. You need to have a good low resistance ground from the sender to the engine and from the engine back to the battery. It also wouldn't hurt to check the connector for corrosion or a loose wire and clean up the other body grounds that are under the hood. I've had more than just a few problems caused by bad or flaky grounds. That's my $.02.

 

No I did not use any sealer on the temp gauge sending unit. I am aware of the grounding issue . I had the erratic gauge problem before I changed the sending unit.(I have had it before "any" of the items I mentioned in my original post were changed) I forgot to add, I also changed the radiator cap also. But like I said too, I'm almost thinking something is up with the gauge. I'll check my ground straps and such, I know my connection on the temp sending unit is good. Thanks!

Superdave

94 Ford Aerostar XL 3.0L
82 Ford F250 4x4 XLT,400 CID,C-6 A/T,8700lb GVWR. Black & Silver

 

One other thought. Is your alternator healthy? What does the gauge do when the key is in the ON position but the engine is not running and it's warmed up? Is there a difference between that and when the engine is running? Is there any difference when engine speed changes? I'm just wondering if you lost a diode in the rectifier that might be giving an AC component to the voltage. You could check your alternator with an analog voltmeter and possibly see the AC component but I doubt you could see it with a DMM that only has a 1-2 sample/sec sample rate. If you're a real geek, you would have an oscilloscope and could catch an AC signal with it.

 

Mikeman, There seems to be no difference on the volt gauge between idle and increasing the motors rpm's with both blowers (has rear air) on with the A/C going. There used to be. So does this mean the alt. is going to puke. I also don't mean to sound smart but what relationship is there between the alternator and the erratic gauges?

Superdave

94 Ford Aerostar XL 3.0L
82 Ford F250 4x4 XLT,400 CID,C-6 A/T,8700lb GVWR. Black & Silver

 

The alternator makes alternating current (AC) that is converted to DC by a diode rectifier that is usually located on the alternator, at least on the "modern" cars that I have - a '91 and '95. So, if one or more of the diodes goes bad, then you're back to having AC or AC with a DC offset. The AC could make the gauge erratic. On my Escort, when the voltage regulator (which contains the diode rectifier ) went bad, you would see the lights go from dim to bright and hear the fuel pump speed cycle up and down at a frequency that changed with engine speed. That was because the electrical power now had an AC component to it with the failed diodes. The temp gauge is just a voltmeter so if the voltage to the sender is changing, you would see the needle on the temperature gauge follow. Also, some of the other gauges would behave in a similar manner if the alternator were wacky. Is the gauge erratic with the enginge off and the key in the "on" position? If you have no other symptoms than the erratic oil pressure gauge, I don't think your alternator is going to puke.

 

>Has any one had any trouble
>with an erratic temerature gauge
>in their Areostars? In my
>94 it recently has been
>running high on the temp
>gauge, over on the A
>in NORMAL and wavering a
>little. The problem has came
>about slowly. It had always
>run between the N &
>O. It has a new
>Modine radiator, new water pump(these
>replaced because of age and
>leaks), new Motorcraft thermostat, fan
>clutch, new Motorcraft temp gauge
>sending unit. I'm beginning to
>doubt the gauge itself. It
>appears the oil pressure gauge
>which is above the temp
>gauge is starting to run
>higher than it normally does
>also. Do these instrument clusters
>use that voltage reducer, like
>the older Ford trucks usd
>to run? I'm about ready
>to hook up a manual
>gauge to see if its
>really running hot. I know
>it not over into the
>"hot" range. But when you
>see your temp gauge running
>half way over the gauge,
>and it hasen't ever been
>there in the 6 years
>you've owned it, its upsetting!
> Thanks.
>
>Superdave
>
> 94 Ford Aerostar XL 3.0L
>
> 82 Ford F250 4x4 XLT,400
>CID,C-6 A/T,8700lb GVWR. Black &
>Silver

Had the same problem with my 93 4.0. There is a fix for it. I found it as a tech bulletin at the nhtsa website. Ford is aware of the problem. Mine occurred when I had to change the water pump. It never really overheats....just cycles alot.

 

I am having occasionally the same problem. Normally, my '93 3.0 Aerostar's temp is around the O and R of Normal. Sometimes it happens, that the needle goes up to the A and back. I've had this happen in all kinds of situations, so I can't see a pattern. It doesn't happen all the time either, just once a while. As long as it keeps going back I don't worry too much about it.

Tom
'93 Aerostar XL 3.0L Extended, 75K mls.

 

Mine is still acting up. However not as bad since cool weather has come. I still have not put a manual gauge on it. Mine is the same way it takes spurts up and down like its the thermostat sticking. I did have the alternator checked out as mentioned above. No problems with the diodes. I too have been into the cooling system for different things. I don't know if I have some air trapped. I did everything as I've always done to try and eliminate any air being trapped.

Superdave

94 Ford Aerostar XL 3.0L
82 Ford F250 4x4 XLT,400 CID,C-6 A/T,8700lb GVWR. Black & Silver

 

I also have a 94 aerostar and my temp guage is just sitting below normal and likes to dance around a little so I know from experience that it isn't right. I replace the thermostat and the heater works a bit better so I know the engine is warming up good, but the guage still likes to jump in and out of the normal range on the low side. My next attempt will be to change out the temp sending unit. See what happens...

Thanks for the info on the thread sealant. I will probably use a little silicone.

 

rdscofield, Are you meaning putting silicone on the threads on the temperature gauge sending unit? If so, don't. It should seal ok with nothing on it.

Superdave

94 Ford Aerostar XL 3.0L
82 Ford F250 4x4 XLT,400 CID,C-6 A/T,8700lb GVWR. Black & Silver

 

Dave, From reading the posts here this may be something to consider.... The Flow of the new pump may be the problem..
Check this out>>>http://performanceunlimited.com/illustrations/thermostats.html<<<
I`ve installed the `balanced` `stat` in mine and the opening is Very consistant. no more `surges` to 220deg before it opens.

Ive used this old trick for air in the system...
drill a 1/8" hole( or smaller) in the flange of the thermostat, where is is exposed to the water flow. Air will `purge` to the radiator and not be held behind the `stat`. As the water heats up a small amount will blead conctantly to the radiator causing the `stat` to open more consistantly.
It is possible that the pump flow rate may be keeping the `stat` from opening. Heat wants open it against spring preasure at the same time the flow through it tends to close it also...


__JOHN__Õ¿ö
Member-
"Crusin North" Car Club
Santa Rosa, Calif.
72 F-250
ICQ#6030753

 

jbhf, Thanks for the info. I checked out the site. I don't think the waterpump is the problem, because I was having the problem before I changed the water pump. I have put in what seems like a half dozen thermostats, the last one being a Motorcraft oem part. Same ole thing
thanks

Superdave

94 Ford Aerostar XL 3.0L
82 Ford F250 4x4 XLT,400 CID,C-6 A/T,8700lb GVWR. Black & Silver

 

[font size="1" color="#FF0000"]LAST EDITED ON 13-Nov-00 AT 02:46&nbsp;AM (EST)[/font][p] Well I've discovered a new twist to this story now, I just for the heck of it just barely turned the radiator cap (which I know is not smart, but as I said just barely) to see if I had any pressure on the cooling system after a 45 mile drive. I turned it barely and heard and felt no pressure, so I turned it a little more, nothing. I took it to the first catch in the cap, nothing. I loosened the cap completely and there was no pressure in the cooling system. It was as if it were stone cold. As I mentioned above, I have a new Modine radiator. Motorcraft thermostat, Stant radiator cap, new water pump. I find no coolant leaks at all. I am afraid I don't want to know what is causing this. Any thoughts? I'm not finding signs of coolant getting into the oil or cylinders.

Superdave

94 Ford Aerostar XL 3.0L
82 Ford F250 4x4 XLT,400 CID,C-6 A/T,8700lb GVWR. Black & Silver

 

This is interesting. Upon turning the radiator cap your coolant ahould have sprayed around. Did you touch the heater hoses? Were they cold?
Just one thought on that erractic temp gauge: you wrote that you have a new radiator. When the new radiator was filled with coolant, how well was the coolant mixed with water? I (mistakenly) did a very interesting experiment: I drained all of my coolant (to change it) and then first added a whole lot of antifreeze and topped off with water - I did not mix. Afterwards, I testdrove it. The needle was jumping up and down all the time. So I drained the radiator again, mixed the stuff well and refilled the radiator. The needle remained stable. Since coolant has a higher boiling point than pure water, I simply guess that the temp gauge sensor was alternatively passed by a richer and leaner coolant mixture whose temperature varied.

Tom
1993 Aerostar XL 3L Ext.