Plymouth Acclaim Overheating

A Good Samaritan Helps Two Ladies With An Overheating Plymouth

Nov 16, 2008

This weekly Q&A session answers your questions about cars and trucks. This week explores a Plymouth Acclaim that has a chronic overheating problem.

Question: 1994 Plymouth Acclaim Overheating

Vincent, These little old ladies that my wife befriended through church have a 1994 Plymouth Acclaim that was overheating. They took it to a local [XXX] name brand shop and this shop recommended everything under the sun, including new muffler bearings and wanted about $900.00. Of course the ladies, sisters, couldn't afford this. They're about 90 years old both. My wife volunteered me because I do like to tinker.

Went and checked on their car yesterday and the coolant looked mostly like water. Upon driving the car around their apartment complex it got hot QUICK. I shut it off before it got fully to the HOT mark. I trailer'ed it to my house because cars are not to be worked on in the apartment complex. The car only has 66,000 miles on it. I replaced the thermostat with the more expensive Stant, about $10.00, because it was said to fail open versus the cheaper one. I of course flushed the system and it was unbelievably corroded due to the near straight, likely, hard water.

New thermostat and gasket, new 50/50 mix in a flushed system, and it still gets hot quick. One thing is the fan would not come on when I took it on the "as fixed" short test ride. And on this ride it got near the 'H'.

However, I read on suite101 that these cars temperatures swing back and forth due to the opening of the thermostat and really cool coolant passing into the engine. But I guess my questions are:

Answer:

You're on the right track here Jason, but you will need to go just a bit further. First off you should have done a reverse flush of the cooling system. Prestone makes a kit to do this and it is very easy to do. Basically it contains a tee fitting that gets spliced into the heater hose, the directions will tell you which one. The tee will accept a standard garden hose and the water from the hose will go through the cooling system in the reverse direction and come out through the filler neck. Just let the water run until it runs clear.

Once it runs clear then you can go in one of two directions. The first is to install the new thermostat and anti-freeze and see where you are. Or you can remove the water pump, install a new one and install the new thermostat and anti-freeze. If the "coolant" that was in there was indeed pretty much water, then it's a pretty good bet the fins of the water pump have rusted away to nothing. When those fins rust away coolant is not pumped through the cooling system to cool the engine.

If you do not want to go the reverse flush route, there are some good cooling system cleaners you can put into the system to clean it out. Assuming you did not use a cleaner first time around.

Once everything is done, put a thermometer into the coolant through the filler neck, start the engine and let it run. By watching the thermometer you will see when the thermostat opens and then at what temperature the cooling fan kicks on. The cooling fan will only operate under these conditions:

So, at idle, the fan should come on at about 210°F and off at 200°F. If not, then there is a problem with the fan circuit. In that case hot wire the fan motor to make sure it is good and runs at normal speed. If it does then the motor is good. Check the fuse for the cooling fan and make sure that it is good as well. Also, see if the fan runs with the A/C is turned on. This will also confirm if the Coolant Temperature Sensor is close to what the actual coolant temperature is.

At this point you will need a wiring diagram to troubleshoot the cooling fan motor electrical circuit. Below is a picture showing the location of the Fan Control Relay.

According to the book, anything between the "H" line and the "C" line is normal operating temperature. But the needle should run about half way between the lines. You will get some increase and decrease when the thermostat opens and closes at first, this is normal, but after a few miles the temperature will stabilize as the coolant remains at a steady temperature.

That's all for this week. Feel free to browse the archives for past topics and other resources. And, as always, if you are stuck and need an immediate answer you can always call Vince on the phone. For a limited time new callers get the first three minutes free!

The copyright of the article Plymouth Acclaim Overheating in Auto Tech & Repair is owned by Vincent Ciulla. Permission to republish Plymouth Acclaim Overheating in print or online must be granted by the author in writing.