Dany89

I have a 87 GTA, everything on my dash bord wroks except for the temp gauge. it doest move at all as if it was stuck any ideas/ suggestions what is the problem and how to fix it??? another thing usually after i trun off the car sometimes i can here the water bubbling and i have to be filling up the rad almost everytime i use my car becuase it seems as some of the water evaporates. i checked the hoses ans none are leaking, the water pump does look a rusty from the outside though

Rockguy

You could have a faulty temperature sending unit. You'll probably have to give it a good visual inspection to see if you can find where the coolant may be leaking.

brians88gta

might be head gasket leaking that would explain the bubbling, compression leaking into the coolant system

bd_slim

iTrader: (1)

my gauge was doing the same thing...changed the sensor in the drivers side head and now it works. some people clean the connection at the sensor and that fixes it, but not for me.

dvardaman85

what exactly is that sensor called and where can i get it

bd_slim

iTrader: (1)

engine temp sensor, drivers side of the head near the front. it has one green wire going to it. you can get it at any parts store.

mikespeed

You should look into that. If you have to add coolant theres a problem. Depending on how the leak is now, and how fast it is progressing, you could do some serious damage to the motor. As a slow leak into a cylinder the coolant will exit the car as steam out the exhaust. ("evaporate" is right) If the leak gets worse coolant could fill whatever cylinder its leaking into and hydrolock the motor.

http://en.wikipedia.org/wiki/Hydrolock
Those connecting rods don't look happy,...


And if the coolant is low, the temp guage may not give you an accurate reading. It should still move. But I would focus on the cylinder head issue first.

brians88gta

if ur coolant is not on the ground it has to go somewere like in the cylinder. check ur oil and plugs see if u can see a plug thats different like a color change might tell u somthing.like were the leak is.

Brighton

In a two fan F-car like my 1990 Formula LB9, the coolant can be heard bubbling (probably into reservoir) when the ignition is turned off if the engine is hotter than normal. It did this this summer when I idled the engine for a few minutes while checking out the alternator. It turned out the primarly fan did not turn on at ~226 F like it should due to a blown fuse and the auxillary fan's (passenger side) coolant switch will not turn close until it hits ~238 F. When I keyed back up after shutting off the engine the temperature was up to about 240 F or higher due to hot soak. So make sure the fuses are okay for both fans and make sure the fans come on when the temperature rises like when stuck in traffic or idling.

Just tonight my dash coolant gauge was stuck at 100 F. I found a loose green wire with white connector while disconnecting the oxygen sensor cable. It was the wire that connects the coolant temperature sending unit to the coolant gauge. It turned out the connect came loose while I was disconnectiong the oxygen sensor wire. The ECM still correctly reads the coolant temperature from the sensor in the front of the engine. I was using a scan tool at the time to read ECT (CTS), O2S, TPS, etc. I stopped at this thread to confirm my gauge problem. I had assumed the ECM and gauge used the same sensor.

The connector on mine slides over the round connector on the sending unit. I read in another thread that 3rd gen F-cars use one of two types of connectors on the sending unit. I could not see the sending unit unless I used a small mirror.

Head gasket leaks will also cause bubbling due to leak into coolant system.

taran02

my gauge is not working at all and when i turn on the car the needle arm shoots straight to the top. and then i can move the needle and it goes back down and then i turn the car off and back on again and it does it again??? it does it with or without the sending unit being hooked up... any ideas???

LS7Roc

Engine temp sensor.

taran02

but it does it even when its not hooked up???

dirtywhiteZ28

The engine coolant temp sensor for Gauge, is a variable negative resistor. That means positive voltage flows from the ignition switch thru the gauge to the sensor, the sensor will change its resistance when the temperature changes, then power gets to ground thru the sensor to the engine. When you first turn on the ignition switch the dash board goes thru a self test, you will see warning lights come on and go off as relevant and the needle gauges will sweep. Your Gauge is working if it moves at all, but if it goes to high and stops there is a short to ground somewhere between the gauge and the sensor. It would be likely that the connector at the sensor has come off the terminal and is now making contact with the exhaust or engine.

Spikeophant

My gauge works sometimes, but is typically pegged out at the top. It doesn't move when I start the car. Should I do the sensor or gauge first? I have a gauge I bought from another member, but he'd never driven the car it came out of.

dirtywhiteZ28

I'd pull the sensor connector off first, then pull out and inspect the sensor, if the "can" shaped part at the bottom looks distorted, ie crushed or swollen. Then its probably the sensor. If the wire is grounding out at the fire wall or under the dash, then the intermittant short could be effected by vibrations from the engine running, check the wiring with the key on, engine off, and the motor at outside air temperature. If you find the short the needle will change. BE aware when you by a new sensor, there are two listed. One for cars with gauge and one for cars with just a warning light. Buy the right one if its needed. Gauges do fail but its easier to "check" the wiring first than to remove, replace, and reinstall the gauge pod.

Spikeophant

Thanks, I'll inspect my wiring when I get off today. I need to pull my column apart and replace the turn signal switch, left doesn't click, and sometimes when I hit a bump the left signal just comes on, not blinking. Really annoying. I'll check out the sending unit for the temp gauge first, and wiring, if they look alright, I'll just swap gauges while I'm doing that.

Spikeophant

I couldn't get any change fiddling with the wires. I didn't pull the sensor and inspect yet, but I did unplug the sensor and start the car, no change on the gauge, would that narrow it down to the wiring or gauge perhaps? It's been rainy and shitty, and my alternator and turnsignal switch have gone out, so I have to replace those first at this point.

B4Camaro91

I thought my g=auge was bad. Replaced the temp sensor, no luck. Found out my thermostat was stuck open and the car was running cool. Works great now.

Goodluck

Sprague

mine doesnt work either. so i did this. but i want the factory one to work[IMG] Uploaded with ImageShack.us[/IMG]
[IMG] Uploaded with ImageShack.us[/IMG]
[IMG] Uploaded with ImageShack.us[/IMG]
the sens with two wires i got from a dealership and the other one is some gauge kit. i cant find a send unit on my head! it looks to all be there?

Sprague

found green wire lol. this is some "JACK-HOLE-WITH-A-CIVIC" job. its plugged off and they put that other temp housing on. i dont know that the 2 wire sensor is though. any ideas? it has a green wire with black stripe and a black wire.

gavin.priestley

hey yall so i just swapped a 350 into my firebird and now when i turn the car on, the temperature gauge needle warms up really quick, but yet once it starts to approach 1/2, itll dance around there. when i first turned the car on after the swap, the needle climbed to hot really fast, yet the water in the radiator wasnt that warm and neither was the engine. So what could this be?

W.E.G.

Gavin, you will generally have better luck getting unique answers on this forum if you start a new thread.

Here, you have revived an eight-year-old thread. Some of the more-knowledgable forum members tend to not respond to zombie threads.

That said, tell us what temperature sensor you are using to connect to your temp gauge. I'm going to assume that you are using a completely different sensor with the 350 than the sensor with which the gauge on your dash was originally paired. So, let's start with that. Tell us about your choice of sensor, and how it is connected to the gauge on the dash.

Secondly, you should have TWO temperature sensors. One feeds the ECM, and the other feeds the gauge on your dash. One sensor is generally located somewhere in the top of the engine in the vicinity of the thermostat housing or the intake manifold. The other temp sensor is on the side of the block. I'm not entirely sure which feeds the ECM vs. which feeds the dash-gauge. Easy enough to figure it out though. Unplug the wire from the sensor, and observe which one causes a reaction on your gauge on the dash. Also, the dash gauge usually is a one-wire connection, whereas the gauge to the ECM is usually two-wire.

Many things can cause a squirrelly dash gauge: Bad sensor, wrong sensor, bad wires, bad gauge, bad ground, and probably others.

You mentioned a motor swap. So, at minimum, you need to use a sensor that is compatible with the gauge with which it is paired. I honestly do not know whether there is a universal calibration curve for all small-block Chevy dash-gauge temperature sensors. From the sound of your report, I suspect that the sensor you are using is the wrong calibration for your gauge.

W.E.G.

This Brit fellow gives a right smashing explanation of how temperature sensors operate:

Kingtut83

hi, can you send a picture of the green wire i have a similar problem i bought a temperature senor hooked it up but not sure what to plug it into ?

Can you help me buy taking a picture

sofakingdom

iTrader: (1)

It's a WIRE, and it's GREEN. Dark green specifically. Not much more that a pic can add to that.

It comes from the harness that runs just inside the driver's side valve cover, and goes over the VC right by the PCV valve to plug into the sending unit which is in the head between the #1 & #3 spark plugs. Has a (usually) white connector on it, if it's still factory. The original sending unit had a kind of "mushroom" connector on it, but most replacement ones have a "blade". No matter though, the factory connector will plug onto one of those too.

Kingtut83

Thanks i figured that that was it
One more question does anything plug into the Ported Vacuum Switch ? Besides the vacuum lines ?

sofakingdom

iTrader: (1)

No, just the 2 hoses.

The little square port is a vent. Has a filter in it.