How accurate is Temp gauge?

[SHOYourYama]

I've done my cooling system maint. about 10k ago:
Thermostat, sending unit, flushed system 50/50 prestone.

My car will run on the "a" in "normal" when driving around town, the fan never kicks on. When stopped and idle, it will go all the way to or above "n" before mr. fan turns on then cools down to the "o".

I get freaked out when the temp is around the "n". I do realize this is in the norm range, but isn't this a lil high?? What letter does a healthy SHO kick the fan on?? And shouldn't the fan stay on till it's back in the "a", not the "o"??

rant headbang shrug

 

[oh_SHO]

From what I understand the temp gauage is not accurate at all. Yours does sound a little on the hot side. My fan kicks on around the 'o' and shuts off a little above the 'a'. My adive is get a laser temp taker to find out excatly what is going on. I plan on getting one.

 

[Ishodu]

Just try a new gauge sender they are cheap.

 

[89 black SHO mtx]

i agree with ishodu. as a temp sending unit ages it gets a build up on it. temp sensor as well(which controls the fan and cold start). try replacing them if they have been in the car for awhile. it couldn't hurt and as ishodu said they are cheap.

 

[Mr Anonymous]

You mentioned replacing the 'sending unit' but didn't specify if that means the ECT sensor or the gauge switch. If it was under $10, it was the gauge switch and you'll want to replace the ECT sensor to get the fan to kick in sooner.

The dash gauge is far from accurate and every car is a little different, but its a good way to monitor trends or sharp changes.

 

[89 black SHO mtx]

SHOooo,
yes you are correct! i didn't clarify myself there thank you sorry about that guys Ken

 

[Dr.Evil]

would there be any way to put a switch in the car so you could turn on the fan whenever? Sometimes I am in traffic and the temp gets up there, and then I park at home while the temp is stil high, and everything under the hood just gets really hot because the fan is not running...so I wanted to put a swich where I could just turn and leave the fan on until it cools back down even if the car is off. My dad's jag already does this, but it shuts off auctomatically when it cools down. has anyone ever tried this?
And then when your friends ask what the switch is, you could say is the NAWWWZZ activation switch

 

[SHOYourYama]

You mentioned replacing the 'sending unit' but didn't specify if that means the ECT sensor or the gauge switch. If it was under $10, it was the gauge switch and you'll want to replace the ECT sensor to get the fan to kick in sooner.

The dash gauge is far from accurate and every car is a little different, but its a good way to monitor trends or sharp changes.

I replaced the ECT, which fixed my running rich problem, but I am still worred about the needle wondering above and on the "n". what if I ran 60/40 prestone, more water then prestone, wouldn't the temp stay down? Or was that the other way around, more prestone = cooler sho?

I like Dr.Evil's idea about the switch, but I want to fix the problem, not compensate for it.

I don't have a laser temp taker, but my volt meter has a thermometer hooked up to a wire, were could I place this to get an acuarate temp reading while my car is running? On the metal thermostat housing? And whats the norm temp range and temp when fan kicks on? I replaced my thermostate w/ a 185 degree unit, should I have gotten the stock 190 degree unit? So many questions... sorry guyz... rant

 

[SHOYourYama]

Just try a new gauge sender they are cheap.

mabey this is my answer.. mine could be inaccurate.. SHOooo, under $10? Might be my first step..

 

[HopefulSHO]

*shrugs* My fan dosen't kick on until the needle hits the N..and then goes off between the O and R...pretty much what yours does. It does it 100% consistantly so I'm not too worried about it. Thermostat opens between the M and A. Something like that anyway...heh

 

[sdpatt]

If the gauge stays around the "A" during normal driving, but reaches "N" before the radiator fan turns on, the gauge and thermostat are likely accurate (relatively) and the ECT sender is switching high. At what temperature did the fan engage before you replaced the ECT? The fan should engage well below the top of the NORMAL scale. You may need the correct ECT sender.

 

[SHOYourYama]

**Thinking** Before I replaced the ECT, I believe the fan would kick on when the needle would just drift above the "m" to the bottom of "r"...

You may need the correct ECT sender.

Did I put in the wrong one? Can't say for-shure, but autozone punched it up on their computer correctly, I love to watch the screen as they type, especially to make shure they are selecting the 3.0 SHO.

*shrugs* My fan dosen't kick on until the needle hits the N..and then goes off between the O and R...pretty much what yours does. It does it 100% consistantly so I'm not too worried about it. Thermostat opens between the M and A. Something like that anyway...heh

It seems mine goes above the "n", doesn't just touch it. tool

 

[SHOfun 93]

SHOYourYama:

Just try a new gauge sender they are cheap.

mabey this is my answer.. mine could be inaccurate.. SHOooo, under $10? Might be my first step..

Yes I am replacing mine soon as well. My temp gauge gives me some funny inconsistent readings. All it consists of is a resistor from what I was told. And for that price, why not start there? I also am installing a water temp gauge as well in order to get an actual number instead of just a general letter reading... boink

 

[SHOYourYama]

Why don't all car's have digital gauges!?! It would save alot of confusion and money down the road..