Chrysler Repair: lhs overheating, water pump impeller, engine coolant


Question
i have a 1995 chrystler lhs and it is overheating. i made sure there was enough coolant in it and there is i think i need a newthermostat but i don't knoww where it was located. can you please help me. it is an emergency. please tell me where the thermostat is, on the top of engine or bottom

Answer
Hi Nicole,
I would not jump to the conclusion that it is the thermostat, but at the end of this you will learn how to find it. Please consider these other possibilities that I wrote to a fellow with a similar problem.
"Either the energy demand of the car is excessive or the cooling capability of the system is compromised. Is there any indication that the brakes are dragging (feel wheel metal surfaces after driving it)? On the cooling side of the question:
Does the engine coolant truly get overheated as evidenced by the both fans coming on when the gauge is in the high area? If not, then maybe the gauge is inaccurate and you might want to measure the temp of the coolant. You didn't say whether you are getting any overflow from the coolant expansion bottle, but that would say it is indeed getting overheated, otherwise a temp check may be warranted.
If it is truly running above typical with the fans coming on, then the possibilities are that although you flushed the radiator some of it tubes are plugged. So check when it has gone into the high area whether both sides of the radiator structure (what are called the manifolds) are quite hot. If the manifold on one side (the side where the lower hose is connected) is quite a bit cooler than the other then I would suspect that you need to have a radiator shop rod out the tubing to restore full flow.
It is also possible that the water pump impeller has lost its ability to pump the coolant because of blade corrosion or being loose on its shaft. On the 3.3L engine the pump is external and is not as big a deal to replace as on the 3.5L engine. On the latter engine it is located internally and you have to do a lot of dismantling to get to it. You said the timimg belt has never been changed so you probably have the 3.3L engine which has a timing chain rather than belt so it won't likely wear out the way a belt does on the 3.5L engine. But if in fact you have the 3.5L it is long overdue for a belt change and that is the perfect time to replace the water pump. If you have the 3.3L with the pump driven by an external belt then you might check to be sure that the belt isn't too loose and allows the belt to slip on the pulley which will of course impair the pumping rate of the coolant.
The last possibility is that you have some air trapped in the system around the thermostat. You can check that out by draining the coolant down by a several quarts, collecting it for reuse. Then notice that there is a bleed valve on the thermostat housing to which you will attach 4' of 1/4 inch clear plastic hose from a hardware store and direct the hose out over the front of the car so as to be able to avoid coolant spilling on the drive belts and to collect the coolant for reuse. Then open the bleeder valve and start adding fluid to the coolant bottle until coolant runs freely out the bleeder valve. While keeping the coolant flowing by adding more to the bottle, gently squeeze the upper radiator hose to drive off air that might be trapped, via the bleed hose. Then close the bleed valve and continue to refill the bottle to the line on the side.
So those are the items that come to mind for what you are experiencing.
Let me know if something comes up that is unusual and I would be pleased to learn in any case what you find to be the cause and the solution."

The thermostat is on the top of the engine, near the front and center. Begin by draining off a quart or so of coolant, collecting it for reuse, from the radiator. If you don't do that when you remove the manifold a lot of coolant will run over the engine and the belts.  All you need to do is follow the top radiator hose from the radiator back to the engine where it attaches to a round manifold. Remove the two bolts that hold that manifold in place and you will find the thermostat inside.
Use a new gasket and be sure to put the thermostat in the hole in the same configuration as the old one. Put the maifold back and tighten the bolts to 20 foot-poinds. Then notice that the thermostat housing has a bleed valve and a nipple from which you can drain fluid. Put a 4' length of clear plastic hose on the nipple and direct the hose over the front of the car to a clean container to catch the coolant. Then open the bleed valve. Then slowly fill the coolant recovery bottle until fluid starts to flow out of the clear hose. The gently squeeze on the top radiator hose until all the air is exhausted from the system. Close the bleed valve and fill the system the rest of the way until it reaches the to of the overflow on the bottle.
Let me know if one of these approaches doesn't solve your overheating problem. For example, are you loosing coolant from the overflow bottle, or do you see any white smoke when you start the car, exiting from the exhaust pipe at the rear of the car? Any coolant on the ground under the car?
Roland