Temp. gauge in dash always reads zero and cooling fans don't come on.

[joebob_]

First of all before I explain my problems to the forum, let me tell you the history of my Mr2. I hate to say it, but I crashed my Mr2. I have been slowly rebuilting my Mr2 ever since that dridged night when I drove my car into the ditch, all because of a selfish ex-girlfriend. That's right ex-girlfriend. They tend to fuckup your life in one way or another. Anywho, let's get back to the problem. I had to rebuilt my radiator besides other things, and in the process the two types of antifreezes, the orange and green scrap, was placed into the cooling system. I have heard that this is not good. This is a rumor, but the two different types of antifreeze will gel up and cause problems. I'm not sure if this is the source of my problems, but I'm telling you the all story so you can help me with my situation. My temperature gauge in the dash always reads zero, and the cooling fans attached to the radiator do not came on. This did not happen until about a year later after I rebuilt my radiator. I have recently had my cooling system flushed with no help with the problems I'm experiencing. I have ohmed out the sensors, the sensor in the radiator and in the engine block, and they both read about 5 ohms, which seems they are shorted. This might be the problem with what I'm seeing, but what are the odds of having two sensors going out at about the same time. Or should I say all sensors that are assoicated with the cooling system are shorted. Could the combination of the two antifreezes did something to the sensors? Have anyone else experienced problems with the combining of the two types of antifreezes? I will be working on this problem for the next few days, but any insight will be helpful. I'm on a time constraint because I'm leave on a week ago road trip, and I would like to know if my engine is overheating or not. On another note, where did these other people learn how to write. I read several other postings, and my head hurts. Trying to figure out what these people are saying. However, thanks in advance for any helpful suggestions.

[JekylandHyde]

If you mentioned what year and engine your MR2 is, I missed it.

If you have a MKII (91-95) the temp sender for the gauge in the dash is different than the temp sensor in the front for the rad fans.

It is fairly common for both to go bad, so you may just be unlucky enough to have them both bad at the same time.

[joebob_]

My car is a 91 turbo. It seems weird that both sensors would go bad. I have also noticed that the sensor in the engine block has two other sensors next to it. One of them is for the cold start sensor, but the other one, I have not figured out what that one is for. Could all of these sensors gone bad.

[JekylandHyde]

There are at least 3 temp sensors:

1. one on the radiator to turn on the fans.
2. one in the engine bay for the gauge
3. one in the engine bay for the ECU

[ac427cpe]

have you checked your relays and fuses?

cooling is a system, so it might not be the sensors only...

[joebob_]

Yes, I have check all fuses and relays in the cooling system, and their good. The third sensor in the engine block, the one I don't know what it is, has only one prong, as the others sensors have two prongs connector. Again, does anyone know what this mystery sensor is?

[kcg795]

What about your thermostat? If opened too far, it'll cause your engine to run too cool. It might be stuck open. I'd look at that too. If it's flowing too fast, it won't have enough time to absorb the heat from the engine, so your fan won't kick on. I have a misadjusted thermostat in my van that's giving me the same symptoms. I was able readjust it a little bit and got the gauge to read a little higher. But I still have to replace it soon so I can get back up to normal operating temperature.