I bought a 93 Toyota Pickup 22re 2wd with around 200k miles. It starts and runs pretty good, but the temp guage barely comes off the cold mark. And the other issue is that the idle seems ver low and sometimes unstable. Im suspecting the heating issue may be the thermostat stuck open was just wondering if anyone else has seen an issue like this? The engine gets warm but not what i think it should be. Not sure about the guage as the needle does actually move off cold slightly as it runs. Also could that cause the idle issue as well? The cab heater does blow pretty warm as well.

 

No help on your engine temp problem, but my 81 does the same thing. Mine is so bad that I removed the cooling fan and blocked the radiator with cardboard just to get some heat in the winter. In fact I've never put the fan back on. I drive it all summer, even in 100 degree weather. The only time mine will attempt to over heat is during the hot summer months and you let it sit still for a long time at idle. I do remove the cardboard in the summer. I've checked and changed the normal stuff, new thermostat, bleed system for air, etc. but still the engine won't heat up.

 

Well, the thermostat is easy enough to check in those. You do need to drain about 1/2 gal or so of water, or else the water will drain one way or another when you pull the thermostat Just 2 bolts to pull, and a couple of hoses to push out of the way.

Could the fan clutch be locked up? If it is, it would be driving the fan full bore, whether it's needed or not. If it's working correctly, you should hear a "whooshing" sound that lasts 30 sec to 1 min after a cold start up, which then fades away. If it doesn't fade away, check the fan to see if it's easy to move when cold. If not, bad fan clutch.

The gauge is known to read incorrectly. It is horribly inaccurate to begin with, and with age, can get worse. You can check it out by pulling the gauge set out, and checking the connections of the gauge. Very slight corrosion, and the gauge reads way off. Just a matter of checking the mounting screws that hold the gauge on the main circuit board. If they've backed off, or have corrosion built up under them over the years, the gauge will be way off. IIRC, there are also some VERY fine wires on the gauge itself. If one, or more, of them os broken off at one end, the gauge will be way off.

Finally, if there is even slight leakage around the sensor's threads, over a period of time, corrosion will build up on the threads. Since the sensor get it's ground from the place it's screwed into, and it reads by varying the resistance to ground, the corrosion will change how the sensor causes the gauge to read. Just pull the wire off the sensor, and unscrew it. ANY corrosion on the threads, or sensor body, can cause big problems. Either use a brass wire brush to clean the threads, or replace the sensor. I don't think they're very expensive. Just make sure the threads they screw into are clean...CLEAN... before you install the new sensor. Also, don't use any teflon tape, antisieze, locktite, etc on the sensor. I believe the sensor that feeds the gauge is the one just behind the thermostat. I may be mistaken on that, however.

 

replace the thermostat, had the same issue. dont even play with it. just replace it.