Hi. I am new to the forum. It was love at first sight with my 85. Took her in and there was no thermostat. So, put one in and new belts. She has always run a little hot (A-L on theNORMAL dummy gauge) in an attempt to cool her down I have done
-new fan clutch
-new radiator
-new water pump
-thermostat
And still she's hot, currently on L most of the time. The heater blows hot and when on she runs hotter. There are no leaks.
I spent days "burping the system". With a laser thermometer I usually find between 190-208. It has never boiled over. It shows no sign of a head gasket problem to my knowledge. I'm stumped and scared of losing her up. It would break my heart. Please help me!

 

If you are showing 190 to 208 theres a possibility tat your gauge is faulty and is reading high or possibly even your sending unit is reading high.


I believe on theses when you unplug gauge should be at full rest with the key on if you ground the gauge it should peg past H.

 

If you're showing 190-208, at the thermostat housing, I wouldn't worry about it. Stock gauges are notorious for inaccurate readings.

 

You probably put a 190 thermostat in it correct? 190-208 would be normal for that thermostat. Get a aftermarket guage set and put it under the dash so you can see what is really going on with oil pressure and temp. You can actually monitor the alternator also if you get a voltmeter too. The factory ammeter is junk.

 

Thanks for the replies. It is a 190. The gauge only goes up when it's actually heating up but hits L and stays. Is it possible to be overheating without boiling over?

 

Rusty. Are you referring to disconnecting the coolant temp sensor to test? Sorry I think I misunderstood earlier

 

Yes disconnecting the temp sensor. Grounding should sweep gauge to past H. That is about the only way to test the gauge.


I know the temp gauge has no adjustment but the oil pressure gauge has a adjustment screw atleast I think that's what it is.

 

Great! I already ordered a temp sensor. But just so I can be sure and get it right. How would you suggest grounding? Electrical is not my deal.
And thanks for your help. Seems like this is related to the probluem I have been throwing money at for a year.

 

well it could be the gauge is off and it could be the sending unit.


There is a way to test the gauges with a resistor that you use a given reistance and the gauge should read at a specific point if not the gauge is faulty.


But if you swap the sending unit and it still reads the same its most likely your gauge is reading high.


I know mine with a 180* thermostat runs just below the start of the line for Normal. I swapped the gauges with a new unit as I installed a Tach cluster same thing.

 

Ok. Thank you. I will be replacing the sensor first. Keep you posted. Merry Christmas.

 

So. Just swapped the sender. And at first with Ac and heat blazing it was dead center. But by the time I got home right back to L.

 

[QUOTE=Rusty_S;15893765]well it could be the gauge is off and it could be the sending unit.

There is a way to test the gauges with a resistor that you use a given reistance and the gauge should read at a specific point if not the gauge is faulty.

But if you swap the sending unit and it still reads the same its most likely your gauge is reading high.
[QUOTE]Does anyone know what size/rating resistor to use to test the gauge? That would be the next thing to do for testing the system.


This will tell you right where the issue is as it is a set value that puts the needle most of the time in the middle of the gauge. If it is not in the middle then issue is from that point back to gauge. If reading high the wire could be shorted to ground, low reading open wire. Or both could show a bad gauge too.


I had to do this on an old car I am restoring to check the fuel & temp gauges.


Is your fuel gauge working right?
Dave ----

 

I think Gary or maybe Fonzie or Jim's Rebel or Ardwrkntrk may know the resistor value, IIRC I've seen it talked about here before.

But, yes, as Fuzzy stated, if the needle is moving toward the high end as it warms up, this could be a short to ground in that wire that leads from the sending unit to the gauge, perhaps the insulation has has been melted or burned and it allows a connection to ground as it heats up.

Tthese gauges are extremely simple; power comes from the ICVR (Instrument Cluster Voltage Regulator) to the dash gauge to the sending unit; the sending unit merely varies the resistance to ground which reminds me, I hope you're not using a crapload of Teflon tape or some such to try and seal those threads, it is that thread <-> block connection that provides the electrical ground for the circuit.

~~

As a general test... with the sending unit wire disconnected, turn the ignition switch to RUN and the gauge should remain on the low end; ground out that wire to a good ground and the gauge should peg fully to the HIGH side (don't leave it this way real long but short-term tests are fine).

If the needle swings fully as you ground/unground the wire, that generally implies the dash gauge itself is fine and you should be looking at the sending unit and the wiring as the source of your symptoms.

Note, gauge operation in the ground/unground procedure is backwards in 1987+ vehicles (at least, I'm pretty sure that's when Ford changed things).

 

Hi all. Thanks for all of your help. It came with tape on it but I didn't add any. The wires seem beat up I'll do some digging for a short but I think this is as good as it gets for me. I was primarily concerned with blowing a gasket, so a faulty gauge puts my mind at ease.

 

The gauges are not to be trusted. If you're 190 - 210 at the thermostat housing you're good.

I've been fiddling with my gauges for years and the temp usually reads on the MAL side of normal.

The instrument cluster voltage regulator ( ICVR ) is a big part of the puzzle. It controls your temp, oil pressure and fuel gauges and if your temp is reading high, your fuel and oil pressure gauges are most likely also reading high.

And if I turn on the HVAC blower motor or head lights my temp, oil pressure and fuel gauges all go up a couple needle widths.

I've swapped out ICVR's (expensive buggers) replaced sending units, added a block to firewall ground, built and installed a really neat solid state ICVR replacement (which worked really well for a few years) and on and on.

It used to make me uptight but now, not so much. I just keep an infrared themometer handy for whenever I might have a fit of gauge anxiety.

One of these days I'll figure out how to remove the aftermarket radio, so I can remove the front dash cover, so I can inspect "G701" which is rumored to be the common ground for ICVR, blower and headlights.

It's either that or I've been thinking about trying a dedicated ground to the instrument cluster to see if that smooths things out.

And then of course there's always the aftermarket option too.