[zugspitz]

After tuneup, New plugs, wires, cap, rotor, fuel filter, Throttle Position sensor cleaning, Engine runs Hotter. Gauge reads just above the middle .

At one point, gauge surged to Hot. Replaced Thermostat..

Then gauge was not reading above cold. Replaced Temperature Sender.

really stumped on this one.

I have read all of the other posts on these issues.

Looking for the Engine to Body ground, not under the Factory Battery tray. The battery is grounded to the Timing cover. ECU grounded from battery to firewall.. found 2 grounds behind Intake to the firewall.

Isnt there a seperate Engine to Body ground ?

The car is 100 percent factory. with 210,000 miles

Water pump replaced in 2000, Radiator replaced in 2002

Could my cooling system just be ready for another overhaul?

Could a tuneup alone cause the engine to run hotter...

Should I even be concerned with the temperature reading Half way on the NORMAL band. Just used to it being in the lower half.

[zugspitz]

Furthermore, I cleaned the engine. I am thinking a bad ground somewhere. Going to put it up on a lift today.

New thermostat from dealer was RT-1139 (193 degrees).

[meangreen92]

Did you maybe retard the timing? That'll make it run hotter. Does the exhaust smell lean?
Your grounds sound like they're all there, the ECU ground is going from the ECU, through the firewall, and to the negative battery terminal?
You can try adding the auxiliary ground cable, as described in the "sticky" thread at the top of this forum.
The only thing I can think of, which you mentioned, is the TPS. You want it to read at .98 volts, with the engine off and the key in the "run" position.
Did you open the cooling system at all, when you were working on it?

[zugspitz]

does smell a bit lean on initial start ups. I guess I need to check the timing. I did not even check the timing since the car was running smooth after replacing spark plugs, etc.

did not mess with the TPS. Cleaned the other one. The Idle sensor I think it is called on the side of the Throttle body. That fixed my surging problem.

Put it on the lift today. The grounds look fine on the back of the motor to the firewall.

I did open the cooling system. Replaced Thermostat, Upper radiator hose, bypass hose on thermostat cover.

I guess it is running hotter. Not just the gauge. The Upper intake manifold and Throttle body is very , very hot. I dont know if that is normal.

[meangreen92]

But you didn't open the cooling system, until you saw the gauge go up?
Did you clean the engine before the gauge went up?
And you changed the gauge sender, not the Engine Coolant Temperature sensor? The sender is threaded into the manifold proper, near the thermostat. The ECT sensor is threaded into the pipes (mounted on top of the intake) which feed the heater hoses and core.
What was the old 'stat rated at? It'll be stamped on the cylinderical part, which faces into the intake manifold.
You can always clean up the contact points of the various grounds.

[zugspitz]

Engine ran hotter after replacing plugs, wires, cap, rotor. Not right after but a few days later.. Then went back to normal. In the lower half of gauge. then the gauge barely was reading. So I replaced the Sender for the gauge. ( the correct one near the thermostat) I also replaced the thermostat thinking maybe it was stuck open.. The old thermostat was from the factory I think. Motorcraft , but no temperature stamped on it. Maybe I should pick up a 180 degree one..

As far as the engine cleaning, that was done before I even replaced the plugs, wires, etc.

And as far as the timing. I can only assume that is still pre set from the factory. Never messed with it.

I can only assume the sender went bad. Causing the eratic movement of the gauge. Now the engine is running hotter after tune up.

Living here in California. I have to leave all of the emmissions BS on. I might have to just take it to the dealer.

probably going to go ahead and replace Radiator and water pump just to be safe.

Thanks for the help.

[meangreen92]

I dunno. Rereading the thread, it does almost sound like a gauge issue.
Does the engine smell hot? Does the push-on connector fit tightly on the sender post? Maybe try cleaning the inside of that connector with a battery terminal brush or something.
If the fuel or oil pressure gauges were malfunctioning as well, I'd suspect the Instrument Panel Voltage Regulator.
When I got my '82 GT, many years ago, the gauge would shoot straight to full hot as soon as the engine got warm enough to move the needle. Acting on something I read in MotorTrend(of all places), I pulled the cluster, and cleaned the contacts from the printed circuit board to the gauge. That fixed it.

[zugspitz]

Yea. I am stumped. The engine does not smell hot. Seems to be running normal. The connector is tight, but I will try to clean the terminal. It is a bit corroded. All other gauges are fine. I was tempted to tear apart the instrument panel and clean it but it seems like a fairly good amount of work to get to the instrument cluster. I am also not real fond of messing with that since the Air Bag in 1990 was the first year. Not even sure if that is working properly. I dont get the Air Bag test light on initial start.

[meangreen92]

Originally Posted by zugspitz

I was tempted to tear apart the instrument panel and clean it but it seems like a fairly good amount of work to get to the instrument cluster.

I am also not real fond of messing with that since the Air Bag in 1990 was the first year. Not even sure if that is working properly. I dont get the Air Bag test light on initial start.

It's no picnic for sure, but I don't think you need to worry about the airbag when removing the cluster - and I'm not comfortable with airbags either. The worst part is when the wires pull out of the hazard switch connector, rendering the turn signals inoperative. If you do ever take it apart, note the postitions of the wires as soon as you detach the bezel - this seems to be somewhat common.

You should be getting a chime if the airbag status indicator light is out.

[jeff/91lx5.0]

Check Your Temp With An Aftermarket Gauge,factory Gauges Are All To Well Known For Being Very Inaccurate.just Buy A Good,but Not Real Pricey Gauge,hook It To The Sending Unit,and See If It Registers Different Than The Factory Gauge,if So,you Know Where The Problem Lies.if It Show's The Same,if You Have A Fan Clutch,it Could Be Failing.

[zugspitz]

Thanks. Just ordered a fan clutch from the dealer. Installed a 3 row "Texas" Radiator. New hoses. New motorcraft thermostat. Sender, New Clutch FAN. The only thing left is the Pump itself.

The gauge is reading Halfway to 3/4. Is that N O R M A L ?

I guess I am just not used to seeing the gauge read so high. I have a feeling I have been running with a stuck open thermostat for a long time... For as the car did take awhile to heat up.. And my heat was pretty much non existant...

Also I do notice that the gauge rises a bit when Lights are on. Maybe a bad ground or dirty connection

[zugspitz]

Also ordered a new Air deflector and a 180 degree Motorcraft Stat. Not taking any chances out here in the Desert.

[meangreen92]

My gauge will rise when the car is off, and you turn the headlights on. I've heard that it is a grounding issue, but I don't know which one.
+1 on the factory gauges being inaccurate.