I have a 1988 Plymouth Caravelle with a 2.2 w/turbo motor. Also w/air. My question is how to route the heater hoses to and from the heater control valve. Does it make a difference which one goes on top or bottom on the heater core. I got this car used and the heater has never worked. I installed a new thermostat and it did very little. I just switched the heater hoses on the heater core and now I have good heat from the heater.But this morning my temp gauge went clear up to hot before the thermostat opened. It has always only gone about half way up the gauge before. Anyway I was wondering if the previous owner has the hoses mixed up on the valve because there are 4 ports on the valve. I have a Chilton's and Haynes manual both have nothing about this subject.
Thank You for any help you can offer.
Having the heater hoses on the control valve routed wrong should have not made the car run hot. If you changed the hoses and you now have heat that is good.
When you switch the heater on vacuum is applied to the heater control valve and closes the valve redirecting the water flow to the heater core.
The core should be on the two hoses that are controlled by the valve.
You said you also changed the thermostat; I would guess that it is installed properly the problem might now be that the engine is air bound and needs to be bled out. After you run the car let it cool down and open the air bleed on the thermostat housing if it is available. Check the water level in the radiator. Make sure there is no pressure in hoses and the engine is cool. You will most likely see that the coolant level is down. Fill up the radiator and run the car again and check the temperature gauge to make sure the temperature is within limits. If air was in the system this could cause the temperature spike.
Another way to bleed the system is to remove the radiator cap when cold and jack up the front end and use jack stands or use ramps to get the radiator higher than the engine. Remember to chock the rear wheels for safety. Run the engine, and as it warms up the thermostat will open up and let the air in the engine out. Be careful of the radiator fan it goes when it reaches proper temperature Continue to fill the radiator till it will not take anymore. Replace the cap and fill the expansion tank to its proper level.
Keep me updated on your progress.
Last edited by TechHelp2 (2/16/2010 9:09 PM)
Thank you for your reply. I should have been more clear. I changed the thermostat some time ago to see if that was the problem with the heater.The system was bled. Right now all I did was flush the heater core by itself and switch the hoses around. I checked the water level and the bleeder and both are fine. That is why I am stumped why all of a sudden the gauge did this. I might add that right after I switched the hoses. I drove it for some time to make sure it was alright. Then early the next morning is when the gauge went up. Also when it got to the red on the gauge I stopped and pulled the connector of the coolant temp sensor to make the fan start. This took only a minute. As soon as I got back in the car the gauge was down to normal. I went on to where I was going and was there about 1 hour; and it was fine going back home. I opened the bleeder and it was fine (had water no air). I let it cool down and added only about a cup of water. Thank you again for your help.
It still sound like it is air bound.
Sometimes it takes a few tries to get the air out.
The engine is technically higher than the radiator. Raising the front end and keeping the rear wheels on the ground will get the radiator higher. In this position and the radiator cap off and the engine running the air can work its way out.
Another thing you can do is watch the coolant reservoir and keep adding coolant. As the engine cools it will suck out the coolant in the expansion tank replacing the trapped air with coolant. This may take a few days. Keep watching the gauge making sure it really doesn't overheat.
The fact that you disconnected the coolant switch and made the fan go on and the temperature gauge went to normal is an indication that the gauge is working. I would still check the gauge for proper function.
If you can get a scanner to read ECM data, compare the engine coolant temp to the gauge reading to see it they are the same. You may be getting a false reading from the coolant temperature gauge sensor.
If you can't get a scanner you can go to a local AutoZone auto parts store and they will usually scan the car for free. Check to see if they still provide that service.
Let me know how you make out.
Last edited by TechHelp2 (2/17/2010 12:59 AM)
Thank you for all your help. You were right on the money. I bled the system and all is good. I took the car to and from work today roughly 30 miles and it did fine. I did not bleed it after switching the heater hoses. I know that was a mistake. Thank you so much for your great advice. GREAT SITE.