Hello all,

Earlier this year, I had the A/C compressor replaced on my trusty 1989 245. A few weeks later, the "check engine" light came on, and I noticed my temp gauge was not moving from the bottom line. I then noticed that the engine was overheating, even after shortish trips.

So, where do I start? I'm not certain what to look for. From reading the boards, I'm guessing Coolant temp sensor or the thermostat. Even with the A/C repair, I'm into the brick for less than $150/ month, and I'd like to keep it that way. Also, if anyone knows of a good shop in Spokane, WA- please let me know. I miss Portland, OR- I was spoiled by the Volvo shops every mile or so!

Could be a stuck closed thermostat, could be a clogged up rad, etc. Have you checked the coolant level/condition? Have you back flushed the fins of the rad with water to get he bugs and dirt of of the fins of the rad? You will be surprised how much dirt clogs the fins up if it never gets flushed/cleaned and that will inhibit airflow. I assume you don't have a condenser mounted pusher fan? My 89 did not have one either, but I added one and have it wired to come on with the A/C, which helps keep me cool even in traffic. What code pops up when you run a self-diagnosis? Your coolant temp sensor will not cause your car to overheat, though I'm not going to say that it is good or bad, just that it's another issue unto itself.
Charles

Check the 700/900 FAQs for instructions on reading and interpreting the check engine codes.

I'll vote for a thermostat. Just because they have a track record of being made by millons and failing by about 10% plus of that per year. Which by the way isn't all that bad. I 'd say headlights are a lot worse.

How many popped eyes do see every night?

Besides thermoststs are inexpensive and easier to change than the other guys down under the manifold. All still require the coolant level to be lowered.

The radiator may need cleaning inside or outside but should heat up on grades as a warning.

If you hear the engine making a boiling rumble sound its hot. I wouldn't wait for the for hood to get hot on any car. Some are insulated for sound which is bad enough that it works against the heat too!


Phil

Well I can start you off with a little info. First off it sounds like you may have a few problems, but hopefully all minor and manageable. There are two different temperature sensors in the engine block. The "temp sender" just connects to the gauge in the cluster. If it fails, it will not throw a check engine light because its function does not effect the running of the motor you would just notice incorrect temp gauge readings. The "coolant temp sensor" or CTS sends its signal to the LH fuel injection computer. If this fails, it WILL set the check engine light and with a missing temp signal the computer will default to an average temp setting resulting in the engine not running at peak performance.

Seeing as how the check engine light is on, you should check the OBD diagnostic codes to get a better idea of what the problem is. I'm not really sure why either of the temp sensors I mentioned would be replaced with A/C work, but I recently replaced my CTS and a few days later got an OBD code for a failed CTS. When I checked it again, I found a fault in the plug itself, an easy splice in fix wit a fuel injector connector.

Finally, is the car really overheating or is the temp gauge just going into the red? If it is in the red, but you put your hand on the hood and it is cool to the touch, then this is a sign of a faulty gauge/sender over a thermostat/cooling system problem.