Questionhad radiator flushed a week ago and car overheated. Antifreeze coming out of the overflow. Diagnostic was done prior to the overheating and said that cylinder 4 is misfiring. Please help a.s.a.p. husband is out with car and stuck
AnswerHi Sandra,
For speed I'm going to copy a response I sent to a person with either a 3.3 or 3.5L engine and was having a similar problem. The only difference is that they didn't say whether or not the coolant was coming out of the overflow. Because of that being present, it could indicate one of two things: either the overpressurization of the system is due to true overheating (the temp gauge should read at full scale, the cooling fans should come on, and the overflow would be steaming) or it could be due to a head gasket leak which will pressurize the system more quickly, might not cause a full scale reading, and might not turn on the fans, and instead you would hear a bubbling sound coming from the engine and radiator fairly early in the warm up period. That I mention because of the misfiring on cyl 4 that you mentioned; that might be another indication of a head gasket leak. But in any case, here is what I responded:
"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 fact that this happened right after the radiator was flushed makes me wonder if the refilling with coolant was not done properly and thus that air is trapped in the cooling system. If that is the case, then try refilling it with coolant (50/50 mixture) after opening the bleeder valve and following the instruction above. If when you open the valve it is already filled to that level, then I would open the radiator drain and drain off a couple of more quarts into a pan (to reuse it) so that the level in the system is below the bleeder valve, then follow the refill procedure.
Those are my most likely answers:air in the system or head gasket leak. The former is a no cost fix, so try it first. Then if you still get overheating I would get a diagnosis for the gasket leak. One other possibility is that the thermostat is not opening properly, and that can be checked by removing it and putting it in hot water and then heating it to boiling and make sure that it opens well before the water boils.
I'll stop now.
Roland
