Temperature gauge

[cano944]

My temperature gauge reads over 3/4 and when I tap on the dash,it goes down to 3/4.Does anyone know if this could be a bad engine temp. sensor or gauge and if this could possibly affect smog tests.I recently had the radiator redone and replaced the thermostat and the radiator coolant sensor.The engine runs OK except it reads too hot.I dont hear any coolant rush or bubbling after stopping the engine so I dont think it is really overheating.Could the the engine coolant sensor read hot if it is bad or vise versa?Could this affect smog tests and engine performance?

Chris

[TheCooler]

Well if its over heating ...yes. I need more info. When you tap it it moves down and stays? If so ..maybe a bad ground? Anyways if 3/4th is the correct temp for the engine, I would recommend getting a new thermostat. My car runs at the 1/4 mark constantly and barely goes above it at a stand still.

[Scott R]

Yes 3/4 is bad, other problems must exist.

[Roger Hall]

If the guage is jumping around especially when you hit the dash, I would clean the grounds. As Cooler suggested.

[SoCal Driver]

Chris, What year car is this?

Please add the info to your signiture under the personal preferences page.

[cano944]

The car does run at 3/4 and the gauge is a little jumpy but not by much.The water never rushes or bubbles but the gauge reads 3/4.I replaced the thermostat,coolant temp switch and the radiator was flushed and it still runs hot.Also,the engine does'nt perform as I think it should.The powerband is not working properly.It feels like a 2 stroke dirtbike when you first start it.You have to blow it out and then the throttle is nice,but it doesnt blow out like that.I get it to 4000rpm and the power decreases and increases and acceleration is poor.I bought this car a couple months ago and I have receipts for water pump,head,new belts etc...so I dont think it is major but has something to do with either the AFM or Throttle sensor.If anyone can help,it is greatly appreciated.Thanks.

Chris

[SoCal Driver]

The 84 uses the single pin temp sender for the gauge. The wire coming off of it has a special slip on connector that looks like a standard one but isn't.

You should have a bit of extra wire in the loom. Pull off the connector from the pin and see if the wire is corroded. If it is see if you can trim off the corrosion and re-solder the wire to the special slip on.

Clean the pin and slip on with carb cleaner and give the slip on a bit of a crimp with some pliers.

[BlueQuestTSi]

Just to add what Hugh was saying, I need to do what he said still.

My temp gauge also read 3/4's and up sometimes. I have been fixing various grounds throughout the car, main battery ground, and running new interior grounds.

Just the other day I pulled out my dash cluster, so I decided to tackle the ground wires back there(brown, they jump from one pin to the lights, etc...) Every since I 'fixed that ground wire, my gauge is never over 1/2, or if it is, it's just for a few seconds. Side effects to this 'fix' have also been brighter dash cluster lights

[SoCal Driver]

Yes! Gauge grounds. Have to clean these every ten years or so. About as often as you have to replace a bulb.

[Baza]

And don't forget the airflow through the radiator.
check out Running hot problem solved

[MrPants]

how do you know which ground is the gauge ground?

[SoCal Driver]

Originally posted by yo mama
how do you know which ground is the gauge ground?

The engine.

[Roger Hall]

Socal
Isn't the ground for the sensor the engine, and the guage has a separate ground that connects up behind the fuse/relay block? I belive on my 81 924 there is a common groung for the guage cluster.

[BlueQuestTSi]

Originally posted by yo mama
how do you know which ground is the gauge ground?

After reading my reply, then looking, you'll understand.

Originally posted by BlueQuestTSi
(brown, they jump from one pin to the lights, etc...)

You can't miss the interior grounds, as they start off in a single pin, then they just kinda daisy chain their way around full circle. The gauge ground starts off in the round plug behind the 'fuel/temp' gauge, it then splits, and bounces across the 2 speedo lights, then over to the tach.

This has go to be the worst case of vehicular grounding I've ever seen. The same ordeal can be found behind the oil pressure gauge. Obviously, Porsche didn't believe that the ground wire was equally as important as power, or they would of at least used a wire that was a couple of AWG's thicker.

[SoCal Driver]

If the gauge is grounded and the sensor grounds to the engine where does the possitive voltage come from to drive the needle in the gauge?

Don't confuse the grounds for the dash lights with the way the resistance gauges work.

Also Porsche does some tricks with applying positive 12 volts to both sides of a circuit as a means of control logic. But not the temp gauge.

[DinoDanny]

I have the same problem. The guage jumps around and then pegs. If I tap on the dash it sometimes goes back to normal for a while. I,ve been under the dash looking for the grounds (no easy task at 6'3'' and 225) and to tell the truth I don't know what I'm looking at or for. I've seen a few brown wires under there that mount to the frame but they are clean and tight.

Could someone give me a realy clear and detailed description of what I should be looking for and where? Thanks in advance.

[mgatlag]

I have a 77 1/2 924 and am having the same problems. Does your temp gauge flutter at idle and then stick when on the gas? I found that if I run a new ground wire directly from the sensor by the rear coolant flange all the way to the back of the gauge itself, the problem stopped. I'd like to slap the person who determined the number and locations for all the grounds on these cars! Some 924's have a circular cluster of ground wires going to them and it's located on the firewall right above the driver's pedals, really fun to get to (have DinoDanny). I've found that the more grounds you add, the better the gauges function, and dash lights get brighter. Good luck!