whats the likelyhood of the OEM gauge failing?

My gauge sits at normal for about 2 mins then just goes past the H. I checked the temp of the water after the thermo and before it reg'ed around 180. I have changed the radiator, water pump, sending unit, thermostat and the hoses. Tried the prestone flush kit and the water seems to go through the engine ok. The radiator is hot at the top and cold at the bottom.

What makes me suspect the gauge is that the thermostat doesnt open tell the gauge reaches H which is odd. Anyone had this problem? The OEM boost gauge doesnt work either.

Is there a way to test the gauge? If i ground the sending unit the gauge goes to H

1988 T2

 

how hard is it to change the gauge?

 

Go to the fsm. You'll find a picture of the water temp gauge. On the face it will show a ohms value for several temperatures. So what you do is buy a resistor of the value given in the picture. You put one end of that resistor on the senders wire connector. The other end of the resistor to ground. After waiting a couple of minutes the gauge should read approx the value shown in the picture. Do that for two or three different temps. An example of what you will see in the fsm is what I'm attaching below: https://www.rx7club.com/forum/attach...postid=2537702

 

There is a test procedure for the sensor & the gauge in the FSM.
(edit) HAILERS is way ahead of me...

 

Here is the page from the FSM:
The whole FSM is mirrored at the link in my sig below.



Also inspect the harness connector socket.
The pins will sometimes back up when the socket is connected.

 

During the summer, my gauge reads 7/8 of the way up. My solution? An aftermarket guage.

 

does the themo sensor work with the sending unit?

Its 180 degrees at the sensor not sure at the sending unit gonna borrow one of those ir heat testers tonight

 

No. The water thermo sensor is totally seperate from the gauge water temp sensor.

But, if you were to put a meter lead up the backside of the ECU's pin 2I, and put the meter on volts, you'd see something like .5volts with a warmed up engine. If you see anything under 4.0 volts.....its hotter than hell. Did I mention pin 2I goes to the water thermo sensor on a series four? I meant to.

Personally, I'd have pulled the thermostat out by now and put the thing back together to see if it ran noticably cooler without the thermostat. That would give you a clue if the thermostat is sticking. That would take thirty minutes or so.

 

Think I might pick up another cluster, the tach craps out sometimes and the boost gauge is dead heh thanks gonna run some volt tests tonight

 

Used one of those infrared temp gauges says the engines around 190, the thermo is around 180 and the radiator at the top is 150-60, Checked the bottom hose it is at 100. Gotta be the gauge